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NUTRIENT MANAGEMENT IN THE TEMPISQUE RIVER BASIN 1

Nutrient Management in the Tempisque River Basin, Costa Rica: Synthesis and Recommendations

July 6th, 2012

Caitlin Pomerance, Andrew Ironside, Victor Martinez, and Courtney Reijo

University of Florida and Universidad de Costa Rica


I. Abstract Located within the Guanacaste region in northwest Costa Rica, the Tempisque River Basin (TRB) has undergone significant land use changes since 1978 when the Arenal-Tempisque Irrigation Plan (PRAT) commenced. PRAT resulted in a series of flood control and irrigation canals that have facilitated an agricultural boom throughout the area. In order to increase crop yields, agricultural producers regularly apply nutrient-rich fertiliser to the soil that may result in runoff into local water sources. The increase in agriculture, fertilizer use, industry, and other human activities are potentially causing increased nutrient loads with possible negative impacts such as alteration of downstream ecosystems, decrease in water quality, and eutrophication. Although Costa Rica’s legal framework includes point source discharge regulations, the country lacks regulations to handle nonpoint source pollution. South Florida’s land use history mirrors that of the TRB and has suffered from many of the same impacts suspected to plague the TRB. Accordingly, south Florida has implemented programs, such as nutrient criteria, Total Maximum Daily Loads (TMDLs), Best Management Practices (BMPs), and Stormwater Treatment Areas (STAs), that may shed light on programs available for the TRB. This report discusses the following questions: 1) what data are available on nutrient loading within the TRB, 2) what are the potential sources of nutrient pollution, 3) what are the potential negative impacts of nutrient loading on downstream tributaries of the Tempisque River, the Palo Verde National Park, and the Gulf of Nicoya, and 4) what approaches should be implemented in order to minimize the potential for negative nutrient loading impacts within the agricultural areas of the TRB?

II. Introduction: History of Land Use and Water Quality Issues in the Tempisque River Basin

Since colonial times, production in the Guanacaste Province of Costa Rica has been limited by several factors including the soil, water, wind, access roads, etc.. The soils in Guanacaste are shallow and stony with long dry periods and strong winds potentially limiting soil productivity.1

The oldest activity in the zone are the livestock farms which were established in colonial times by several actors. These communities created the “Haciendas” (i.e., big pasture farms) for large cattle production in the flat geography presented in most of Guanacaste.2

For the farmers to be able to have large pastures, it was necessary to cut down most of the tropical dry forest, and during the process, they exploited the precious timber species that existed within. Forest exploitation for domestic market and cattle production for exportation to Nicaragua became the two principal activities from the 1800’s, and the Tempisque River Basin (TRB) was used as the main access route to the Peninsula de Nicoya from the mainland until the early 1900’s.3 From the pre-colonial times, the water has been the principal conditioning factor for the development in the Peninsula de Nicoya (including drinking and navigable water). This characteristic of the water comes from the range of abundance across the seasons as water can

1 Echeverria at al. 1998. Mentioned by Gordon W et al. 2004. Biodiversity Conservation in Costa Rica: Learning the lessons in a seasonal Dry Forest. University of California. p. 5.2 Peters G 2001. La Cuenca del Tempisque: Una perspectiva históricaa. p. 9.3 Id. at (10)


rise and cause flooding in winter, and it can be a complete drought in the dry season that may last from five to seven months per year. These radical weather changes have determined the extent of agricultural production within the region.4 In Guanacaste from the early 1900’s, the rice and sugarcane were produced for local trade, but in the 1940’s, the first big development tool was the Panamerican Highway (“Carretera Interamericana”). It was implemented across Costa Rica which gave the population of the Peninsula de Nicoya the access necessary to the central valley and its market. As a consequence of this market opening, agriculture expanded in the Peninsula for these two products as well as the cattle supply for the domestic meat market across the country. The second tool used to develop the Peninsula was the irrigation canals that made it possible to produce agricultural products with relative stability against the seasonal variations and extreme conditions of the area. The irrigation project started in 1974 with the construction of the Arenal Dam that passes the water from the Atlantic to the Pacific slope in a 100 m3/s volume. In 1978, the Arenal-Tempisque Irrigation Plan (PRAT) began, and in 1988, more than 6,000 hectares (ha) had become available for agricultural use. By 1995, the second stage of PRAT, it added 12,700 ha to the agricultural land, and the project is still under construction. The goal is to cover 60,000 ha by the irrigation channels in order to promote the development in the region by an increase of the agricultural production.5 The rise in agricultural production observed over the past 20 years coincides with the implementation of the Arenal-Tempisque Mega Irrigation Project (he makes reference to the PRAT) diverting the water from the Caribbean to the TRB in the middle of the 1980’s.6 Practically all of the rehabilitated land is used for agricultural proposes (90%), specifically sugar cane and rice fields because of the soils presented in the zone. The sugar cane and rice fields are concentrated in the lower basin of TR where this zone limits with or its in the recharge zone of Palo Verde National Park (PVNP), and the impacts of these activities are directly related to and part of the PVNP wetlands. It can be observed in Figure 2 the agricultural land use (not including cattle ranching) passed from 0% in 1950’s to 24.7% in 2000. Most of this agricultural land is used in rice and sugarcane plantation fields, and these activities are important for development in the zone but are probably causing ecological problems in basin lower lands of the TRB. In the Figure 3 (2008 data) it can be seen that the agricultural development in the TRB have been in the surrounding area of the irrigation canals, the sugar cane its the main product in the irrigation projects representing 57% of the coverage that it presents, however it is important to observe the agricultural zone that surrounds the PVNP. The TRB virtually produces half of the national production of sugarcane and rice and also a high percentage of the cattle ranching.7 These activities, principally the first two, require a high level

4 Id. at (12)5 ICE 2012. Términos de Referencia para: Estudio de factibilidad de modernización de Arenal. Anexo 1. p. 29.6 Jimenez et al. 2005. Conceptualization of Environmental Flow in Costa Rica: Preliminary Determination for the Tempisque River. Organization for Tropical Studies- Union International for the Conservation of Nature. p. 12.

7 Gordon W et al. 2004. Biodiversity Conservation in Costa Rica: Learning the lessons in a seasonal Dry Forest. University of California. p. 16.


of fertilization for its cultivation, but when farmers don’t apply the fertilizer pack (all the fertilizer that are used in one period of cultivation) with the right techniques, it runs off with the water that is used to grow the plants and is released into the canals or natural streams that discharge into the main rivers of the zone and the wetlands.8

Figure 2. Comparison of land use in the TRB between 50 years of difference. Taken from Conceptualization of Environmental Flow in Tempisque River, Costa Rica.

8 OTS. 2006. Manejo del riego en el cultivo del arroz. p. 5.


Figure 3. Land use of the TRB in 2008 based on the OTS data. Solid levels peak in the water periods just before the seeding periods in the farms of the surrounding areas of the PVNP when the Fangueo is applied in the farms.9 This technique is probably applied at a similar time in the rest of the farms in the TRB because of the season and the rice cultivation periods in the year, the biggest applying time differences are around two months between the farms in the zone. The water coming out from rice fields does have a high fertilizer content but shows low to moderate nutrient contents, such a nitrate, and it is supported by current research when it is said that Palo Verde Marsh (PVM) and other wetlands in the region may be N-limited.10 11 A 2011 study also found that the phosphorus (P) concentration is very elevated compared with other wetlands such as the Florida Everglades.12 13 It can be observed in Table 1 that the difference is really considerable and probably the managing practices will present variation in each place because of the context and the scenario presented.

9 Rizopatrón. 2003. Pestidies, Nutrients and Suspended Solids in a wetland of Costa Rica. Universidad Nacional. p. 40.10 Rodriguez-Ulloa. 1997. Vigilancia de las aguas superficiales en la zona de influencia del proyecto de riego Arenal - Tempisque. Universidad de Cosa Rica.11 Osland et al. 2011. Restoring diversity cattail expansion: disturbance, resilency, and seasonality in a tropical dry wetland.. Organization for Tropical Studies. p. 11.12 Id. at (11)13 Craft and Richardson. 2008. Soil characteristics of the everglades. p. 59 - 72.


Table 1. Comparisons of P-concentration between two wetlands PVM and the Everglades.Site µg/mL

PVM 530

Everglades 50 The continuous invasion of wetlands by agriculture in the TRB has resulted in negative impacts to the original ecosystem because of its loss to be replaced with crops, and the consequences of this agricultural invasion in the wetlands are starting to be noted in the modification of the natural habitat in the park like the rapid expansion of an aggressive invader plant in the rest of the ecosystem as the Typha dominguensis in the PVM.14

Typha rapid expansion as a response to anthropogenic actions such as: nutrient enrichment, altered sediments rates and others. In many tropical and subtropical wetlands elevated P-inputs have been linked to landscape scale Typha expansions.15 The first two related actions to the rapid Typha expansion in wetlands are being done in the surrounding area of Palo Verde National Park because of the intensive agriculture, and some practices that are being applied and are not the best to manage the crops in the most efficient way.

14 Gordon W et al. 2004. Biodiversity Conservation in Costa Rica: Learning the lessons in a seasonal Dry Forest. University of California. p. 8.15 Osland et al. 2011. Restoring diversity cattail expansion: disturbance, resilience, and seasonality in a tropical dry wetland.. Organization for Tropical Studies. p. 2.


The techniques used in the rice cultivation may affect the wetlands stability in PVNP because of factors like an increase of sediment concentration and an increase of nutrients and pesticides waste in the drained water.16 As it can be seen, the problem had been projected 20 years earlier in the 1980’s when only the first stage of the canals was made, and the canals construction have been expanded to the second stage (around 12,000 ha more) and it’s still under construction. Currently, SENARA has registered 28,000 ha. The objective of this study is to provide the respective authorities with accurate recommendations and possible mechanisms in order to manage nutrient rates in the Tempisque Basin water systems and their possible negative impacts on surrounding areas.

III. Stakeholder Analysis In water quality (WQ)The main stakeholders about the water quality status in the TRB are: -SENARA because this institution is in charge of the management of the irrigation projects hence the water that comes in the TRB from Arenal, -MINAET is the minister concerns about the water policies, water concessions and collect water pollution fees, the third stakeholder involved is MINSA who is the minister that establish the quality of the water by applying tests in the different sources. ControlThe control in the water of the TRB can be presented as water quality tests, but it could be implemented as preventive control, by making educational campaigns to promote the use of good agricultural practices, the stakeholders for this function would be: OTS and SENARA. WaterThe institution in charge of the water volume that is irrigated in the TRB from Arenal Dam is ICE, that’s why this institution is a direct stakeholder about the water volume that is distributed. Development modelingThe stakeholders that are directly related with the development model applied in the TRB are the local governments, Incopesca, CONARROZ and IDA, the municipalities are the organizations who develop different policies to promote the development in the zones, the potential models for the zone might be: -Tourism, -Agriculture, -Fishing farms and others. The IDA is the institution of Agricultural Development; its function is to set projects in marginal zones of the country to generate an economic growth and social welfare. CONARROZ is the only institution that gives support to the farmers about the cultivation techniques and how to improve the methods17.

IV. Introduction to the Tempisque River Basin Water Resources Costa Rica is a country naturally rich in water resources as the tropical humid climate of the region creates a rainy season lasting over seven months (April to December). It is estimated that that the country’s overall annual runoff is 2,200 millimeters with an outflow of 3,557 m3/s.18

16 Quinn et al. 1992. mentioned by Rizopatrón. 2003.Pesticides, Nutrients and Suspended Solids in a wetland of Costa Rica. Universidad Nacional. p. 25.17Interview to Alexander Blanco, Rice Farmer in the Low Tempisque River Basin. 18 Calvo, J.C. “Water resources development in Costa Rica 1970-2000.” Hydrological Sciences Journal 35(2): 185-196. 1990. p. 185.


The mountain ranges in Costa Rica divide the country into two main slopes – the Caribbean/Atlantic slope and the Pacific slope. The Volcanic Mountain Range of Guanacaste, with a maximum elevation of 2,030 meters above sea level, marks the headwaters of the Tempisque River Basin (TRB) which includes the Tempisque and Bebedero Rivers.19 The TRB has an area of 5,454 square kilometers, equivalent to 54 percent of Guanacaste province and 10% of national territory.20

During the period 1970-1987, the percentage of available water doubled from 6% to 12% due to the creation of dams such as the Arenal-Tempisque Irrigation Project.21 This project allowed intensive irrigation and crop production to become the primary land use within the Tempisque River Basin.22 The Irrigation Water Authority (SENARA) started the construction of the Arenal-Tempisque irrigation district in 1980. This 76,000 hectare district uses 75 m3/s of water from the Arenal hydroelectrical complex for 54,000 hectares in the Arenal district and 20 m3/s from groundwater deep wells and baseflow from the Tempisque River for an additional 22,000 hectares in the Tempisque district. Today, hydroelectric dams are Costa Rica’s and the Tempisque Basin’s primary source of energy. The Costa Rican Electricity Institute (ICE) controls the majority of installed hydroelectric plants including the 1975 construction of the Arenal-Tempisque Irrigation Project. ICE continues to plan for construction of new dams in order to meet the electrical needs of the growing population.23

Intensive agricultural areas including crops of grain, sugarcane, melon, rice, and livestock, dominate both the physical and economic landscapes of this region. Other land uses include forestry plantations and cattle ranching. All activities have an environment cost in terms of water quality contamination and soil erosion which makes it necessary to use limited resources more beneficial for society.24 The prevalence of irrigation use in the Tempisque has created concerns for increased water pollution, inadequate water use, deterioration of upland watersheds due to dam construction, and lack of nutrient pollution management.25 For this reason, it is supported that water resource availability is not a problem in general; however, water scarcity and allocation conflicts, interconnected to water pollution issues and uneven water distribution over space and time, has created concern for the continued supply and quality of Costa Rica’s water, especially in the Tempisque Basin.26

Water utilization in the TRB is representative of water resource changes that have taken place in Costa Rica since the 1970s. From this time period, domestic and urban consumption of water has increased with increasing populations while sanitary disposal of wastewater has had

19 Id.20 Mata, Alfonso. “Watershed Ecology and conservation: Hydrological Resources in the Northwest of Costa Rica.” Chapter 9 in Biodiversity Conservation in Costa Rica: Learning the Lessons in a Seasonal Dry Forest. Eds. Gordon Frankie, Alfonso Mata, and S. Bradleigh Vinson. University of California Press, Ltd. 2004. p. 115.21 Calvo, J.C. “Water resources development in Costa Rica 1970-2000.” Hydrological Sciences Journal 35(2): 185-196. 1990. p. 190.22 Id.23 Id.24 Mata, Alfonso. “Watershed Ecology and conservation: Hydrological Resources in the Northwest of Costa Rica.” Chapter 9 in Biodiversity Conservation in Costa Rica: Learning the Lessons in a Seasonal Dry Forest. Eds. Gordon Frankie, Alfonso Mata, and S. Bradleigh Vinson. University of California Press, Ltd. 2004. p. 115.25 Calvo, J.C. “Water resources development in Costa Rica 1970-2000.” Hydrological Sciences Journal 35(2): 185-196. 1990. p. 190.26 Id. at 185


a larger effect on localized water supplies.27 The major problems facing this sector, in the TRB and across Costa Rica, include: urbanization, inadequate water supply system maintenance, increased treatment costs due to surface water pollution, absence of water quality monitoring, and lack of watershed and aquifer protection.28

These issues are consistent with increasing concerns related to other sources of potential water pollution including aquaculture (especially tilapia farms), industry, and unregulated rural or urban water use and management.29 Nitrogen and phosphorus fertilizer additions increased when the Arenal-Tempisque Irrigation Project allowed for more intensive crops which has enabled farmers to irrigate crops during the dry season and almost doubled rice and sugarcane yields.30 Although this has had positive effects on the economy and livelihood of the rural and industrial communities in the TRB, agriculture intensification often includes a substantial increase in the rates of fertilizer application which both improves yields and has deleterious consequences for downstream aquatic systems, where nutrient loading can drive eutrophication downstream.31 Specifically, since mid-1970s, crop agriculture (particularly rice, sugarcane, and melons) has replaced most of lowland pastures which once was used for cattle grazing. Forest cover is sparse except within the boundaries of protected parks. With this landscape-level shift, nutrient loading to streams has become a more recent concern.32

In general, water resource issues in the TRB, in regards to nutrient and pollution management include lack of: point and nonpoint source pollution management, downstream protection measures (especially the Gulf of Nicoya and Palo Verde National Park), water quality regulations, and incentives for onsite nutrient management.33 As of today, there are increasing concerns for the downstream protection of the lower reaches of the Tempisque River, Palo Verde National Park, and Gulf of Nicoya which are located south of the intensive irrigation, agricultural, and ranching lands located throughout the basin.

V. Water Quality Data Synthesis: Potential Sources and Impacts of Nutrient Loading in Tempisque Basin Streams, Palo Verde National Park, and Gulf of Nicoya

Synthesis of Current Water Quality Data Although concerns about potential increases in nutrient loading (due to increases in the extent and intensity of agricultural, industry, and ranching through the basin) have become more prevalent in the Tempisque River Basin, there is a lack of knowledge about the possible sources of nutrients as well as the impact increased nutrient concentrations may have on lower Tempisque River reaches, Palo Verde National Park, and the Gulf of Nicoya. According to a prominent researcher from the Universidad de Costa Rica, there is little to no physical and chemical data that exists for the TRB today although recent efforts have been made to

27 Id. at 18928 Id. 29 Id.30 Hagamen, L. “The impact of land use practices on nutrients in freshwater streams, Guanacaste, Costa Rica.” Thesis. Brown University. 2008. p. 9.31 Id. at 632 Id. at 933 Calvo, J.C. “Water resources development in Costa Rica 1970-2000.” Hydrological Sciences Journal 35(2): 185-196. 1990. p. 9.


monitor water quality parameters across various land uses.34 It has been suggested that nutrient monitoring needs to take place at boundaries of different land use areas in order to demonstrate the potential impacts various land practices have on the contribution to overall increases in nutrient inputs to the Tempisque and Bebedero Rivers.35

It is evident that there is a general lack of knowledge and data in regards to water flows and nutrient levels within the Tempisque River. A synthesis of past literature on nutrient levels within the Tempisque River included a few papers on which little patterns or conclusions could be drawn. Although no comprehensive conclusions can be made given the lack of scientific data, the following sections will discuss if nutrient loading in the Tempisque River is a reason for concern, what evidence is available to determine potential sources of nutrients, as well as the potential implications for negative impacts on the Gulf of Nicoya and Palo Verde National Park due to nutrient transport. Impacts on Streams Systems within TRB and Implications for Downstream Protection Massive fish and shrimp mortalities have been observed in the Tempisque River in more recent years.36 The rate of mortality has been attributed to the addition of xenobiotic substances introduced by land erosion and discharge from agricultural lands and organic wastes from the sugarcane industry. Although sugar factories have been improving their pollution prevention measures (i.e., minimizing point and nonpoint pollution to surface waters), the fast-growing aquaculture of tilapia fish in artificial ponds pose new threats due to large demands of water and creation of water pollution. These potential impacts are also shared with other crop production, domestic water uses, ranchland, and wastewater discharge. Nutrient discharge levels to or relative impacts on the Tempisque River from these various sectors has not been extensively studied. All studies on the Tempisque River have been inconclusive as no systematic sampling has been conducted, creating a need for thorough research on the biota, biogeochemistry, and hydrology of the Tempisque River throughout its reach.37

As of the present date, only two studies have been found that include instream measurements within the Tempisque River while no information on the Bebedero River was present. A 1995 study focused on the instream water chemistry of several tributaries of the Tempisque River in order to address the potential extent that runoff from adjacent lands governs instream chemical composition. The second study, done in 2008, addressed the issue of the lack of studies that have focused on the effects of land use change on Costa Rican or tropical stream water chemistry.38 This study focused on measuring potential land use effects on instream water composition.

34 Astorga, Yamileth. Personal interview. 14 June. 2012. 35 Id.36 Vargas, J.A. and M. Alfonso. “Where the dry forest feeds the Sea- The Gulf of Nicoya Estuary.” Chapter 10 in Biodiversity Conservation in Costa Rica: Learning the Lessons in a Seasonal Dry Forest. Eds. Gordon Frankie, Alfonso Mata, and S. Bradleigh Vinson. University of California Press, Ltd. 2004. p. 129.37 Id.38 Hagamen, L. “The impact of land use practices on nutrients in freshwater streams, Guanacaste, Costa Rica.” Thesis. Brown University. 2008. p. 7.


In a 1995 study, solute export across six tributaries of the Tempisque River, located in the Guanacaste Conservation Area, were measured in order to evaluate the influence of runoff on instream solute composition as well as the effects the five month dry season (December to April) has on stream chemistry.39 The six tributaries included three smaller (0.36-0.55 square kilometers) and three larger (2.6-3.2 square kilometers) rivers which each had a gradient (i.e. slope) of 10%. The flow and water chemistry was measured at an elevation of 580-600 meters where a large portion of land downslope from the sites was used primarily for grazing although the majority of the land within the study catchments was evergreen or rain forest with minimal anthropocentric disturbance.40 Results showed that the concentrations of nitrate (NO3

-), total dissolved phosphorus (TDP), and dissolved organic carbon (DOC) were relatively constant seasonally but increased considerably during stormflow events. The TDP showed most variability as levels increased with drawdown of baseflow during the dry season. The major cations measured included calcium (Ca+2), magnesium (Mg+2), and sodium (Na+). These elements had a distinct seasonal pattern where low concentrations were found to be variable during the wet season and increased during baseflow recession in the dry season.41 In general, the concentrations of NO3

-, TDP, and DOC were directly related to stream discharge during stormflow (i.e. correlated to runoff) while the major cations were inversely related (i.e., dilution effect.42 The researchers of this study suggested that an increase in major cations may be reflective of mixing of cation-rich deep groundwater (exposed to weathering) and cation-poor shallow sources which governs high flows.43 Differences seen in the solute concentrations among the six streams seemed to be a function of area-specific runoff where streams with higher runoff have lower concentrations of solutes, representing the influence runoff has on export differs between the regional and local level. At the regional level, runoff is influenced by factors such as rainfall, temperature, humidity, solar radiation, etc. At local scale, variation in runoff is reflective of precipitation.44 The main conclusions of this study suggested that nitrogen limitation does not appear to be affecting productivity in any studied stream, phosphorus is suggested to likely limit algal productivity as the streams were retentive of low but constant N and P concentrations.45

The majority of studies that have been done have focused on small pasture stream watersheds in the Amazon Basin following deforestation. In general, these studies have shown that a conversion of tropical forest to pasture reduces nitrate, increases ammonia and dissolved organic nitrogen concentrations and these patterns shift over time following deforestation where an initial pulse in N loss is followed by decreased losses as the pasture degrades to low total ecosystem N levels.46 In 2008, twelve subwatersheds of the Tempisque River Basin, consisting of different land uses (>50% agriculture, forest, or pasture) were sampled during the first two months of the

39 Newbold, J.D., Sweeney, B.W., Jackson, J.K., and L.A. Kaplan. “Concentrations and export of solutes from six mountain streams in Northwestern Costa Rica.” Journal of the North American Benthological Society 14(1): 21-37. 1995. p. 21.40 Id.41 Id. at 2542 Id. at 2943 Id. at 3044 Id. at 3245 Id. at 3546 Hagamen, L. “The impact of land use practices on nutrients in freshwater streams, Guanacaste, Costa Rica.” Thesis. Brown University. 2008. p 7.


five-month dry season.47 Stream water chemistry parameters included dissolved oxygen (DO), conductivity, water temperature, salinity, pH, ammonia, nitrate (including nitrite), and dissolved organic nitrogen (DON).48 The study found that the discharge amounts varied by land use.49 50 51 There were no trends in DO (6-9 mg/L) or pH while the concentrations of nitrate, ammonia, and DON all increased with increasing agricultural cultivation in the watershed.52 53 Likewise, nitrate decreased with increasing forest cover; however, there was no significant differences in nitrogen concentrations between pasture and forested watersheds.54 In general, it was suggested that high rates of nitrogen fertilization (rice 140-180 kg N/ha/yr; sugarcane 100-150 kg N/ha/yr) may be increasing nitrogen availability in streams which may potentially be driving eutrophication55. Agricultural activities within the Tempisque River Basin are increasing nutrient availability in adjacent streams which can potentially stimulate plant growth, modify DO levels, and alter benthic communities.56 These two studies have suggested that: 1) runoff from adjacent land is a major predictor of instream water chemistry within the Tempisque River Basin, 2) local rather than regional land use practices have stronger influence on stream water nutrient levels, 3) irrigation may drive pulses of high nitrogen concentrations, and 4) direct inputs from agricultural canals may minimize in-stream nitrogen processing, allowing for increases in stream nitrogen concentrations.57 58 Overall, land use practices have potential to influence the water quality of downstream ecosystems. Impacts on Palo Verde National Park There is widespread evidence of the biophysical, productive, and social changes that have transformed the Tempisque watershed over the last five centuries which now consists of a complex matrix of agricultural lands, wetlands, protected areas, and human settlements.59 Prior to PRAT, the economy was largely based on extensive cattle ranching. The Arenal-Tempisque Irrigation Project (PRAT) is now Costa Rica’s premier producer of rice and sugar cane which has had a positive influence on the economy of the Tempisque Basin. More recently, the impacts

47 Id. at 848 Id. at 1349 Id. at 1450 Id. at 551 Id. at 14 The variation in soil type and parent material (which was volcanic rock in origin but with different ages) was consistent with variations seen in land use, preventing the analysis to determine possible influences on landscape characteristics on stream nutrients.52 Id. at 1553 Ammonia, nitrate, and DON increased linearly as the proportion of agriculture within the watershed increased, and the land use within 1 kilometer upstream from the sampling site best described the variation in nitrogen concentrations compared to land use within 500-, 2000-, 5000-meters upstream or within the entire watershed. 54 Id. at 1555 Id. at 1656 Id. at 2257 Newbold, J.D., Sweeney, B.W., Jackson, J.K., and L.A. Kaplan. “Concentrations and export of solutes from six mountain streams in Northwestern Costa Rica.” Journal of the North American Benthological Society 14(1): 21-37. 1995. p. 36.58 Hagamen, L. “The impact of land use practices on nutrients in freshwater streams, Guanacaste, Costa Rica.” Thesis. Brown University. 2008. p 20.59 Arriagada, R. A., Sills, E. O., Pattanayak, S. K., Cubbage, F. W., and E. González. “Modeling fertilizer externalities around Palo Verde National Park, Costa Rica.” Agricultural Economics 41(6): 567-575. 2010. p. 568.


of rice production, agricultural practices, and ranching on Palo Verde National Park have become reasons for concern.60 The Palo Verde wetland includes 20,000 hectares of seasonally dry forest consisting of limestone outcrops and extensive wetland vegetation bordering the Tempisque River. Today, irrigated rice, sugar cane, and melon cultivation are increasingly the dominant features of the basin as the more reliable water supply has allowed farmers to move from one to two crops a year. Soil sediments and agricultural runoff in the drainage water adjacent to Palo Verde have been identified as the primary causes of degradation of the wetlands located inside the park. Overall, the shift from traditional to intensive irrigated farming has resulted in an increase in use of fertilizers and pesticides and these shifts have been suggested to result in water contamination and erosion in outflow areas.61

From 1926 to 1977, the Palo Verde National Park was used for cattle ranching and in 1977 a portion of the land became a National Wildlife Refuge.62 In 1980, the land adjacent to the Refuge became Palo Verde National Park, and in 1990 the refuge and park boundaries vanished, combining the areas under the park regulation.63 During this time, the PRAT project began, cattle were removed from the wetland when it went under protection, and five weirs (established in 1979) which had previously been used to maintain flooding in the area during the dry season were removed.64 Through all these changes, what had once been an open marsh, dominated by floating vegetation and almost no tall emergent vegetation, became the largest cattail (Typha domingensis) marsh in the region within only a few years.65 A negative effect of this change is seen in that the thousands of birds that once were present within the have decreased in numbers as Typha rapidly expanded across the region.66 Typha expansion has occurred predominantly because this species is very resilient and they have been documented to thrive under conditions of eutrophication, salinity, acidity, etc—those conditions otherwise intolerable to most plant species.67 Nutrient availability, specifically that of nitrogen, phosphorous and potassium, typically controls plant growth in wetland ecosystems and when one or any combination of these nutrients is increased, a positive response in plant growth, for many species, will be observed. Typha, however, exhibits exceptionally increased plant growth in response to nitrification.68 It is likely that an increase in nutrient inputs could result in an increase of cattail growth. A study of soil and water chemistry was conducted in June and July of 2009 at eight different areas of Palo Verde.69 The water analyses included measuring magnesium (Mg), potassium (K), sodium (Na), and phosphate (PO4).70 This study found that there were significant differences in

60 Id. at 56761 Id. at 56862 Robichaux, E. S. “ Influence of Soil and Water Chemistry on Marsh Plant Communities in Palo Verde National Park, Costa Rica.” 2009. p. 14.63 Id. at 1564 Id. at 1865 Id. at 1566 Id. at 1567 Id. at 1668 Id. at 1669 Id. at1070 Id. at 10


soil and water chemistry from the northern and southern areas of the park. These difference in chemistry may be a result of greater marine influences in the south as this areas of the PVNP had much higher concentrations of marine influenced elements (Cl, S, Na).71 Despite the chemical differences, it was found that soil N, P, and K and water nitrate, P, and depth had significant effects on species richness across both the north and south parts of the park. Species richness also increased with a decrease in elemental concentrations in the soil and water. It is suggested that these findings, all though not comprehensive, support alternative hypotheses on the spreading of Typha throughout Palo Verde, one of which could be changes in or the influence of nutrients on this region.72

Impacts on Gulf of Nicoya Gulf of Nicoya Hydrography and Ecology The Gulf of Nicoya is a tectonic estuary that extends 80 kilometers southward from mouth of the Tempisque River to the Pacific Ocean and from 3 kilometers wide at mouth of Tempisque to 50 kilometers wide at southern extent.73 The two distinct regions of the Gulf (upper and lower) are based on the shape, bathymetry and hydrography. The shallow upper Gulf encompasses 40 km north of Puntarenas Peninsula and San Lucas Island and is less than 20 meters deep.74 The water composition in the upper Gulf is less saline than the lower parts of the gulf and is bordered by mangrove swamps and sandy beaches. The lower Gulf deepens to 200 meters and is bordered by rocky cliffs.75

The Gulf of Nicoya is among the largest tropical estuaries (1,530 square kilometers) in Central America, is a main fishing area in Costa Rica, and considered to be characteristic of tidally driver, tropical estuarine systems.76 The Gulf represents an estuary with unique ecological characteristics as well as unique hydrography which in turn creates unique physicochemical attributes. Fishing is a primary industry for the area which contributes 90% of national fish catches and supports over 3000 artisanal fishermen and their families (15,000 people in total).77 78 Some of the many species include sea bass, catfish, porgy, mackerel and bonito.79 The upper Gulf ecosystem is an extremely important habitat and nursery ground for fish and shellfish,. In economic terms, the fisherman earn over 200 times as much in the upper gulf than the lower gulf. The mangroves that line parts of the upper and lower Gulf provide an extensive root system for spawning grounds and hatcheries of various fish, crustacean, and mollusk species while they also filter out pollutants introduced from coastal areas.80

71 Id. at 7072 Id. at 7073 Id. at 42874 Id. at 42875 Id. at 42876 Wolff, M., Chavarria, J.B., Koch, V., and J.A. Vargas. “A trophic flow model of the Golfo de Nicoya, Costa Rica.” Revista de Biología Tropical 46(6): 63-79. 1998. p. 1. 77 Id. at 278 Whelan, T. “Environmental contamination in the Gulf of Nicoya, Costa Rica.” Ambio 18(5): 302-304. 1989. p. 302. 79 Id. 80 Id.


In 1979 a research program to study the Gulf was established at the University of Costa Rica and foreign scientists were invited to work with local experts and more than 80 papers were published, making the Gulf one of the best known tropical estuaries.81 The studies focused on the identification and classification of new communities of fauna present within the Gulf. Three studies on nutrients, dissolved oxygen, and trace metals were conducted through this program with a limited number published in more recent years.82 A need for more extensive information on water quality within the Gulf is evident as declines in fish and shrimp populations have become persistent, more red tides have been noted, and external pressures from coastal development have increased.83 The Gulf differs from most temperate counterparts in that much of the nitrogen entering the system comes from offshore deep water which is upwelled into the Gulf.84 85 The hydrography is unique as there is a clear mixing process in the upper and lower regions of the Gulf. In the upper Gulf, the riverine waters from the Tempisque River, high in nutrients and low in salinity, mix with the surface waters from the lower Gulf which are high in salinity and low in nutrients. This creates an intermediate mixing area between the upper and lower Gulf as well as a halocline within the upper Gulf. In the lower Gulf the upper Gulf waters mix with oceanic waters which are high in salinity and nutrient concentrations.86 Input to the Gulf comes from three rivers, the Tárcoles, Tempisque, and Barranca Rivers. During the rainy season, freshwater input from these rivers averages 150 m3/s, 50 m3/s, and 40 m3/s, respectively.87 The discharge of the Tempisque, Barranca, and Tárcoles Rivers creates a southward flow of water through the upper Gulf along the surface waters of the eastern shore.88 This is countered by the inward flow of offshore water at deeper levels with a flushing time—the amount of time required to replace all the existing fresh water at a rate equal to runoff discharge—was estimated to be one to two months.89 These flows create a high energy midgulf where mixing takes place.90

The lower Gulf is highly stratified with a permanent thermocline between 25 and 40 meters. Surface water is generally warmer than 26°C while bottom temperatures can fall below 13°C. Salinities in the lower Gulf are consistent seasonally and usually above 32‰. The upper Gulf is stratified with a temporary halocline during the rainy season but salinities rarely fall below 25‰

81 Vargas, J.A. “The Gulf of Nicoya estuary, Costa Rica: Past, present, and future cooperative research.” Helgolander Meeresunters 49: 821-828. 1995. p. 821.82 Epifanio, C.E., Maurer, D., and A.L. Dittel. “Seasonal changes in nutrients and dissolved oxygen in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Central America.” Hydrobiologia 101: 231-238. 1983. p. 231.83 Id.84 Wolff, M., Chavarria, J.B., Koch, V., and J.A. Vargas. “A trophic flow model of the Golfo de Nicoya, Costa Rica.” Revista de Biología Tropical 46(6): 63-79. 1998. 85 Voorhis, A.D., Epifanio, C.E., Maurer, D., Dittel, A.I., Vargas,J.A. “The estuarine character of the Gulf of Nicoya,an embayment on the Pacific coast of Central America.” Hydrobiologia 99, 225–237. p. 225.86 Kress, N., Coto, S.L., Brenes, C.L., Brenner, S., and G. Arroyo. “Horizontal transport and seasonal distribution of nutrients, dissolved oxygen and chlorophyll-a in the Gulf of Nicoya, Costa Rica: a tropical estuary.” Continental Shelf Research 22: 51-66. 2002. p. 60.87 Whelan, T. “Environmental contamination in the Gulf of Nicoya, Costa Rica.” Ambio 18(5): 302-304. 1989. p. 302.88 Vargas, J.A. “The Gulf of Nicoya estuary, Costa Rica: Past, present, and future cooperative research.” Helgolander Meeresunters 49: 821-828. 1995. p. 127.89 Id.90 Whelan, T. “Environmental contamination in the Gulf of Nicoya, Costa Rica.” Ambio 18(5): 302-304. 1989. p. 302.


and temperatures range from 26-30°C.91 The thermocline prevents significant mixing which mainly occurs in the mid-Gulf region.92

The vertical stratification of the upper Gulf was described in a 1996 study where higher nutrient concentrations were found at deeper levels up until the mid-Gulf mixing zone where almost the entirety of the water column mixes (tidal kinetic energy dissipation and wind stress are great enough).93 The highest nutrient concentrations were found in the deeper waters of the mouth of Gulf (i.e., lower Gulf) where the primary source of water is the Equatorial Subsurface Water (ESW) which is characterized by very low oxygen concentrations, low N/P ratio, which may contribute to nitrogen limitation in the area. To date, no estimation on the amount of nutrient enrichment due to ESW water in the Gulf of Nicoya has been made but it has been suggested that the inputs are far greater than freshwater inputs from streams (i.e., Tempisque and Tarcoles Rivers).94 Also noted was that water leaving the Gulf appears to be enriched in silica relative to the water carried in.95

Data from the stratification of the Gulf shows that the ESW remains under the thermocline in the lower Gulf but it is suggested that under certain conditions (meteorological or oceanographic extremes) that the deep water can enter into the upper Gulf and mix vertically, contributing to the primary production of the area.96 It is suggested that this possibility may explain the inconsistencies seen in the 1987 and 1993 studies in regards to seasonal variation in runoff-driven nutrient imports.97 98 99

The Gulf of Nicoya is characterized by the distinct rainy and dry seasons of Costa Rica. Rainfall in the Gulf region varies from less than 50 mm/month in the dry season to over 600 mm/month in the rainy season.100 During the rainy season, the entire gulf is strongly stratified due to high riverine discharge. During this time surface temperature decreases, salinity increases towards the seas, and most of the Gulf is undersaturated with dissolved oxygen.101 During the dry season, the Gulf remains stratified but without the strong freshwater signal seen in the rainy season.102

The chemistry of Gulf also relates to the unique hydrography, influence of the ESW and riverine discharges, as well as meteorological and oceanic events. The deep waters below 30 meters

91 Epifanio, C.E., Maurer, D., and A.L. Dittel. “Seasonal changes in nutrients and dissolved oxygen in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Central America.” Hydrobiologia 101: 231-238. 1983. p.323.92 Id. at 23593 Chaves, J., and M. Birkicht. “Equatorial Subsurface Water and the nutrient seasonality distribution of the Gulf of Nicoya, Costa Rica.” Revista de Biologia Tropical. 44(3): 41-47. 1996. p. 43.94 Id.95 Id.96 Id. at 4597 Chaves, J., and M. Birkicht. “Equatorial Subsurface Water and the nutrient seasonality distribution of the Gulf of Nicoya, Costa Rica.” Revista de Biologia Tropical. 44(3): 41-47. 1996. p. 45.98 Valdes, J. C.L. Brenes, E. Solis and M. Mendelewict. “Propiedades Csico quimicas de la aguas del Golfo de Nicoya, Costa Rica.” lng. Cienc. Quiin- II: 2 1-25. p. 1.99 Cordoba-Munoz, M. del R. “Productividad primaria en la columna de agua. Golfo de Nicoya, Costa Rica.” M.Sc. thesis, Universidad de Costa Rica. San Jose, Costa Rica. 1993. p. 1.100 Kress, N., Coto, S.L., Brenes, C.L., Brenner, S., and G. Arroyo. “Horizontal transport and seasonal distribution of nutrients, dissolved oxygen and chlorophyll-a in the Gulf of Nicoya, Costa Rica: a tropical estuary.” Continental Shelf Research 22: 51-66. 2002. p. 53.101 Id.at 51102 Id. at 51


depth are undersaturated with dissolved oxygen and in the lower Gulf oversaturation reaches up to 134% at the surface.103 Silicic acid (Si(OH)4) is found in higher concentration during the rainy season due to weathering and erosion of volcanic rocks.104 Phosphate (PO4) has shown to not be seasonally dependent while surficial NO3 and NO2 levels in upper Gulf are higher in the dry season and are lower in dry season in the lower Gulf. Surficial chlorophyll-a levels (chl-a ; the green pigment used to determine algal biomass) are higher in the rainy season, especially close to the Tárcoles outflow (located in the Tarcoles River Basin to the east of the TRB).105 Overall, the Gulf of Nicoya is a unique estuary that differs extensively from other estuaries around the world in terms of hydrography, chemistry, and ecology. While much information is known about the communities of the Gulf, more information is needed to determine the main drivers of water quality and associated red tide events which have become more common. Algal Blooms in Gulf of Nicoya Algal blooms in the Gulf of Nicoya, also known as red tides, have become more intensive and have persisted longer in recent years. Blooms usually occur for several weeks in the early rainy season months of April and May.106 Although the red tide has not yet extensively affected businesses, tourism, or fisheries, there is worry that the earlier presence, longer duration, and intensity of algal blooms will begin to impact tourism and the economy of the area which many livelihoods depend on.107

Red tide, a naturally occurring algal bloom which often gives color to the water when in high concentrations, is caused by autotrophic phytoplankton which includes photosynthetic algae groups termed diatoms, cyanobacteria, and dinoflagellates.108 Diatoms and dinoflagellates represent the greatest number of phytoplankton groups in the Gulf of Nicoya, specifically.109 110 Some types of dinoflagellates can secrete toxins which can be absorbed by shellfish (e.g., mussels and oysters) and cause severe effects on humans. Symptoms of coming into contact or ingesting such toxins range from skin discomfort and rashes, to vomiting and nausea, to paralysis and death.111 Dinoflagellate blooms have become a more common feature of the Gulf of Nicoya. Although no extensive reports of human illnesses due to dinoflagellate toxins have been limited, reports

103 Id. at 51104 Id. at 63105 Id. at 51106 Norman, C.R. March 30th, 2012. “In Nicoya Gulf, the deadly red tide lingers.” TicoTimes online newspaper. 30 March. 2012. Web. 1 July 2012. p. 2.107 Id. at 3108 Phytoplankton are the autotrophic (i.e., photosynthetic) group of plankton which creates the basis for the majority of oceanic and freshwater food webs and rely on macronutrients such as nitrate, phosphate, and silicic acid in order to fix carbon compounds through primary production. The most important groups of phytoplankton include diatoms, cyanobacteria and dinoflagellates. 109 Diatoms are one of the major groups of algae and most common type of phytoplankton. They are characterized as unicellular organisms that exist as colonies in the shape of either filaments/ribbons, stellate colonies, zizags, or fans. Diatoms are also unique as they are encased within a silica (hydrated silicon dioxide) cell wall called a frustule which can be preserved within sediment upon dying of the organism. 110 Dinoflagellates are the next largest group of marine eukaryotes after diatoms. Many are photosynthetic or mixotrophic where photosynthesis and ingestion of prey are combined.111 Norman, C.R. March 30th, 2012. “In Nicoya Gulf, the deadly red tide lingers.” TicoTimes online newspaper. 30 March. 2012. Web. 1 July 2012. p. 2.


of shellfish poisoning and health effects due to red tides have occurred in past years.112 113 According to the National University’s (UNA) Phytoplankton Laboratory, four people died from eating contaminated shellfish in 1972 and two children died from paralytic shellfish poisoning in 1989.114 At the end of February (2012) Costa Rica’s Agriculture and Livestock Ministry, which manages the laboratories that test mollusks for toxicity, had reported that the algal species Gymnodinium catenatum, known to emit dangerous toxins, were found in a red tide in the Gulf of Nicoya; however, there was no indication that toxins were present in the water.115 The main organism identified in a 1995 bloom event was Cochlodinium catenatum but more recently, multiple bloom occurrences by other organisms have taken place.116 Low phytoplankton concentrations are generally observed in the Gulf during the dry season with the first red tide outbreak occurring in the last week of April (coinciding with the change from dry to rainy season).117

A variety of bloom-causing species have been identified, including Mesodinium rubrum (identified mainly in the lower Gulf), Prorocentrum balticum, and Gymnodinium catenatum. Most blooms quickly died off within a few months although some have persisted until the onset of the dry season.118. Potentially toxic species have also been observed as minor constituents of the C. catenatum blooms, such as Alexandrium catenella, Alexandrium monilatum, and Pyrodinium bahamense.119 Although human illness have not become a prevalent problem due to dinoflagellates, negative ecological effects of blooms include death of fish eggs, suffocation of coral reefs, and decay of high biomass reduces water quality and potentially hypoxia affecting marine fauna.120 Questions still remain on the toxicity of some of the dinoflagellates, and the relative importance of nutrient ratios, grazing, and interaction with light penetration and water column stability.121 Answers to these questions will only be determined through continued monitoring and research efforts. The presence of red tide is a natural phenomenon; however, these algal blooms can be exacerbated by anthropogenic pollution and increased amounts of nutrient inputs (i.e., nutrient enrichment). Large inflows of nutrients from agricultural runoff, raw sewage, wastewater, and fertilizers (containing phosphates and nitrates) can cause blooms to become exacerbated and extensive. Furthermore, the upper Gulf has been shown to be particularly prone to conditions perfect for algal blooms to become uninhibited.122 The cause of increases in algal blooms within

112 Id. 113 Viquez, R., and P.E. Hargraves. “Annual cycle of potentially harmful dinoflagellates in the Golfo de Nicoya, Costa Rica.” Bulletin of Marine Science 57(2): 467-475. 1995. p. 467. 114 Norman, C.R. March 30th, 2012. “In Nicoya Gulf, the deadly red tide lingers.” TicoTimes online newspaper. 30 March. 2012. Web. 1 July 2012. p. 2. 115 Id. 116 Viquez, R., and P.E. Hargraves. “Annual cycle of potentially harmful dinoflagellates in the Golfo de Nicoya, Costa Rica.” Bulletin of Marine Science 57(2): 467-475. 1995. p. 467. 117 Id.118 Id. at 472119 Id. at 472120 Id. at 473121 Id. at 474122 Norman, C.R. March 30th, 2012. “In Nicoya Gulf, the deadly red tide lingers.” TicoTimes online newspaper. 30 March. 2012. Web. 1 July 2012. p. 2.


the Gulf of Nicoya has been an issue of debate for over 20 years and is today more of an issue of concern as blooms become more extensive and intense. Literature Review on Potential Nutrient Sources in the Gulf of Nicoya Scientific recognition of the influence of offshore waters and riverine discharge as the primary sources of nutrient import and enrichment in coastal areas of the Gulf of Nicoya has been generally agreed upon throughout recent scientific literature. The extent to which each source contributes to the spread of algal blooms, however, is unknown.123 The first extensive nutrient and dissolved oxygen study of Gulf of Nicoya took place in 1983 and suggested that algal blooms were due to offshore imports. This study also found a seasonal change in nutrient concentrations where nutrient levels were a magnitude higher in the rainy season in the upper Gulf.124 A following 1987 study concluded that the seasonal variation in nutrient levels in the upper Gulf were due to changes in river discharge but found that the highest concentrations of nutrients were found during the dry season, a phenomenon that was not fully explained.125 A 1996 study suggested that the major source of N and P to entire Gulf (averaged over the upper and lower gulf sections) was the ESW.126 A study published in 2002 concluded that the introduction of nutrients into the Gulf due to increased riverine discharge in the rainy season appears to explain the high chl-a concentrations found in the mouths of the three main rivers (Tempisque, Barranca, and Tárcoles Rivers) in the Puntarenas area. There was an inverse relationship between chl-a and % oxygen saturation which is contrary to what would be expected if photosynthesis was occurring in these regions.127

The stoichiometry of nitrogen, phosphorus, and silicon found within the Gulf shows some evidence that the area is nitrogen limited. In general a N:P ratio < 10 and Si:N ratio >1 indicates stoichiometric N limitation while Si:N ratio <1 and Si:P ratio <3 indicate silicon limitation and N:P ratio >20-30 suggests a phosphorus limitation. In the Gulf of Nicoya, the N:P ratio (where N included estimates of NO3 and NO2) were always lower or equal to 10, Si:N ratios were always higher than 1; and Si:P ratios were always higher than 7. This suggests that the Gulf of Nicoya is potentially limited by nitrogen availability which is likely due to riverine water composition being high in phosphorus (creating low N/P ratios).128

Seasonal changes in levels of dissolved oxygen, ammonium, nitrite, nitrate, and inorganic phosphorus were measured in the Gulf of Nicoya in 1983.129 Dissolved oxygen (DO) in the

123 Chaves, J., and M. Birkicht. “Equatorial Subsurface Water and the nutrient seasonality distribution of the Gulf of Nicoya, Costa Rica.” Revista de Biologia Tropical. 44(3): 41-47. 1996. p. 41.124 Epifanio, C.E., Maurer, D., and A.L. Dittel. “Seasonal changes in nutrients and dissolved oxygen in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Central America.” Hydrobiologia 101: 231-238. 1983. p. 231.125 Valdes, J. C.L. Brenes, E. Solis and M. Mendelewict. “Propiedades Csico quimicas de la aguas del Golfo de Nicoya, Costa Rica.” lng. Cienc. Quiin- II: 2 1-25. p. 1.126 Chaves, J., and M. Birkicht. “Equatorial Subsurface Water and the nutrient seasonality distribution of the Gulf of Nicoya, Costa Rica.” Revista de Biologia Tropical. 44(3): 41-47. 1996. p. 41.127 Kress, N., Coto, S.L., Brenes, C.L., Brenner, S., and G. Arroyo. “Horizontal transport and seasonal distribution of nutrients, dissolved oxygen and chlorophyll-a in the Gulf of Nicoya, Costa Rica: a tropical estuary.” Continental Shelf Research 22: 51-66. 2002. p. 60.128 Id. at 63129 Epifanio, C.E., Maurer, D., and A.L. Dittel. “Seasonal changes in nutrients and dissolved oxygen in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Central America.” Hydrobiologia 101: 231-238. 1983. p. 231.


upper Gulf in the dry season generally above saturation while bottom never exceeded 90%.130 This suggests that there is substantial primary production at the surface, degradation of biological material at the bottom, and partial mixing between surface and bottom waters. Dissolved oxygen (DO) in the upper Gulf during the rainy season is usually below saturation at both surface and bottom most likely due to increased loads of organic material entering from Tempisque River.131 The surface water of the lower Gulf is generally supersaturated with DO regardless of the season which is most likely due to photosynthetic activity.132 The deep waters of the lower Gulf were never saturated with oxygen and was less than 25% during rainy season.133 Little seasonal change was seen in phosphate which is typical of most estuaries and may be related to the geochemical adsorption reactions of phosphorus.134

Ammonium was found to be relatively high at the mouth of Tempisque River regardless of season most likely due to agricultural activity. However, high amounts of ammonium were found through the upper Gulf during the rainy season suggesting that a secondary source of ammonium is present.135

The main source of nitrogen within the Gulf was ammonium which oxidizes to nitrate downstream of the mouth. Nitrate values were higher at the Tempisque River mouth and decreased downstream during the dry season suggesting that oxidation of ammonium and subsequent uptake by phytoplankton is occurring downstream and that the ammonium input during the rainy season exceeds the nitrifying capacity of the upper Gulf.136 The surface waters in the lower Gulf mirrored those of the open Pacific and were low nutrients while bottom waters were rich with nitrate during both seasons.137

Concentrations of nitrogen increased seaward during both seasons. The nitrogen-rich water at the bottom of the lower Gulf shared characteristics of the Equatorial Subsurface Water that underlies the surface (e.g., high nitrate, low oxygen, high salinity, low temperature).138 The values suggested that water enters the lower Gulf at lower depths along the western shore and that estuarine water leaves along the surface of the eastern shore. This pattern is related to the geomorphology of the Gulf, the diminished effects of the Coriolis force at the near-equatorial location (contrary to northern hemisphere estuaries), and is supported by more recent studies.139

In a 2006 study, it was determined that nutrient rich equatorial subsurface water (ESW) is upwelled in the lower gulf of the Gulf of Nicoya and is thought to be a major source of nutrients to the area.140 The study investigated the dominant sources of nutrients in the upper Gulf,

130 Id. at 233131 Id. at 233132 Id. at 234133 Id. at 234134 Id. at 234135 Id. at 235136 Id. at 235137 Id. at 235138 Id. at 235139 Id. at 235140 Palter, J., Coto, S.L., and D. Ballestero. “The distribution of nutrients, dissolved oxygen and chlorophyll a in the upper Gulf of Nicoya, Costa Rica, a tropical estuary.” Journal of Tropical Biology 55(2): 427-436. 2006. p. 431.


the influence of nutrients on primary productivity and oxygen concentrations, as well as the seasonality of nutrient fluxes to the estuary.141

Turbidity and DO levels appeared to be influenced by the magnitude of freshwater and organic matter (OM) flux from the Tempisque River. High turbidity readings coincided with a decline in DO likely caused by OM flushed into the system from the River in the rainy season.142 Likewise, the Tempisque can elevate the upper Gulf’s concentrations of suspended solids to 800 mg/L during the rainy season which is likely causing light limitation on productivity making allochthonous inputs greater than autochthonous.143 The nutrient concentrations measured in the study (nitrogen, phosphorus, dissolved oxygen, etc.) all increased with proximity to the Tempisque River also suggesting high riverine influence.144 The chlorophyll a concentrations (a proxy for phytoplankton biomass) were at maximum at Tempisque River mouth but was uncoupled spatially with nitrate measurements (i.e., surface chlorophyll concentrations are patchy while there is a distinct continuum of NO3

- concentrations).145 146 The 2006 study concluded that the Gulf of Nicoya has lower concentrations of nitrate and nitrite but is enriched with phosphate when compared to North American estuaries. The average nutrient concentrations were not discernible from similar studies done in 1979-1980 or 1981-1982 or 2002 but that rainy season maxima for nitrate, nitrite, and phosphate found at the mouth of the Tempisque were higher than for each previous study.147 148 149 Overall, it was suggested that the dominant control on the spatiotemporal distribution of nutrients is not offshore sources but rather the freshwater flux from the Tempisque is likely the largest source of nutrients throughout the year (although the influence of the ESW should not be underestimated for the lower Gulf).150 This study further supports the need for more seasonal measurements should be taken to better quantify possible patterns. Lastly, a biogeochemical balance model was created in 2006 for the Gulf of Nicoya using surface water and deep water sources of nutrients.151 The Gulf of Nicoya was determined to be a net source of dissolved inorganic nitrogen (DIN) with an availability rate of 87x103 mol/day in the dry season and 3,044 x 103 mol/day in the rainy season. Likewise, dissolved inorganic phosphate (DIP) in the Gulf is 27 mol/day in the dry season and 207 mol/day in the rainy season.152 The seasonal nutrient dynamics seen in N and P (correlated to runoff seasonal

141 Id. at 427142 Palter, J., Coto, S.L., and D. Ballestero. “The distribution of nutrients, dissolved oxygen and chlorophyll a in the upper Gulf of Nicoya, Costa Rica, a tropical estuary.” Journal of Tropical Biology 55(2): 427-436. 2006. p. 431.143 Id.144 Id.145 Id.146 This may suggest that, where chlorophyll levels are high and nitrate levels undetectable, nitrate is being entirely consumed in these areas.147 Epifanio, C.E., Maurer, D., and A.L. Dittel. “Seasonal changes in nutrients and dissolved oxygen in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Central America.” Hydrobiologia 101: 231-238. 1983. p. 231.148 Palter, J., Coto, S.L., and D. Ballestero. “The distribution of nutrients, dissolved oxygen and chlorophyll a in the upper Gulf of Nicoya, Costa Rica, a tropical estuary.” Journal of Tropical Biology 55(2): 427-436. 2006. p. 434.149 Valdes, J. C.L. Brenes, E. Solis and M. Mendelewict. “Propiedades Csico quimicas de la aguas del Golfo de Nicoya, Costa Rica.” lng. Cienc. Quiin- II: 2 1-25. p. 1.150 Id.151 Tabash, F.A. “A biogeochemical model for the Gulf of Nicoya, Costa Rica.” Journal of Tropical Biology 55(1): 33-42. 2006. p. 33.152 Id.


variations) fit the biological processes for the Gulf such as variation in primary productivity levels and maturity/reproduction seasons of species.153 The introduction of nutrients into the Gulf as a result of increased levels of leaching during the rainy season seems to explain the increase in the concentration of chlorophyll-a and it was concluded that the main source of nitrogen (nitrate) was found at the outlet of the Tempisque and Tárcoles Rivers.154 Although it appears that offshore sources of nutrients are the major source in the Gulf of Nicoya, the negative effects of increased anthropogenic nutrient loading should not go unwarranted. The studies mentioned have all supported the need to develop a more complete inventory of nutrient inputs and outputs within the Gulf of Nicoya ecosystem, including the difficult task of quantifying the flux from offshore waters, and across the various land uses of the Tempisque River in order to determine the driving forces of water quality across the Basin.155

VI. Costa Rica’s Water Quality Legal Framework

The Constitution The highest law in Costa Rica is the Constitution. Unlike the United States Constitution, however, Costa Rica’s Constitution has environmental protection written into it. The Constitution states: “Every person has the right to a healthy and ecologically balanced environment, being therefore entitled to denounce any acts that may infringe said right and claim redress for the damage caused.”156 The Constitution also lists under the country’s cultural aims the “protection [of Costa Rica’s] natural beauty.”157

Environmental and Water Quality Law

The Ley General de Agua Potable charges the Ministerio de Obras Publicas and the Ministerio de Salud (MINSA) to construct systems of potable water supply in order to protect the sanitary and physical integrity of the water. The Ministerio de Salud must assess applications for construction and modification of potable water systems and recommend to the Ministerio de Obras Publicas those works that are of the most important based on studies of mortality, the quantity of parasites, etc.158 The Ministerio de Salud is also responsible for designing, constructing and maintaining potable water treatment systems,159 as well as regulating activities that affect environmental health. Further, the municipalities are charged with the administration of systems that produce potable water for their communities.160 Additionally, the Ley General de la Salud establishes water as a public good of which human

153 Id.154 Id.155 Chaves, J., and M. Birkicht. “Equatorial Subsurface Water and the nutrient seasonality distribution of the Gulf of Nicoya, Costa Rica.” Revista de Biologia Tropical. 44(3): 41-47. 1996. p. 41.156 Articulo 50.157 Articulo 89.158 Id. at Articulo 2.159 Id. at Articulo 3.160 Id. at Articulo 5.

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use takes priority over all other uses.161 Administered by the Ministerio de Salud, the law prohibits the contamination of water resources, or harming or obstructing those resources that are designated for human use.162 It states that contamination is the introduction of any foreign element or any substance whose purpose is other than the improvement of the quality of the water.163 Further, the law prohibits any person from destroying or harming systems of public or private sewers, or preventing their functioning.164

Finally, the Ley Orgánica del Ambiente establishes the general mandate to treat water before discharging it into a body of water. In particular, it makes clear that all residual waters must be treated before they are discharged into any rivers, lakes, oceans, or any other body of water. The required treatment must also take into account the quality of the receiving water body and the treatment necessary to respect its current and potential future uses.165

MINAET and CIDECAT The Ministerio de Ambiente, Energía, y Telecomunicaciones (MINAET) is the central government agency in Costa Rica charged with managing Costa Rica’s water supply. In 2002, MINAET established a list of guiding principles for national water management. Principally, the MINAET declared that access to potable water is an inalienable human right which must be constitutionally guaranteed.166

Further, the regulation stated, inter alia, that water as a resource should be governed under the principles of equity and social and intergenerational solidarity167; that water is a public good168; that the ecological function of water is necessary for the health and life of all species ecosystems169; and that the best modern infrastructure and technology should govern water use to prevent contamination and waste.170

MINAET also established the criteria and methodology that should be used for the evaluation of superficial water sources and the classification of the various uses to which those waters may be put171—the order applies to all superficial waters in Costa Rica.172 The order defines superficial water sources as all fresh water springs, rivers, streams, lakes, lagoons, artificial or natural dams, environmental flows, and marshes.173 The methodology follows the Dutch Classification Index and the Biological Index (BMWP-CR).

161 Capitulo 1, Articulo 264.162 Capitulo 1, Articulo 273.163 Id.164 Capitulo 1, Articulo 290.165 Ley Orgánica del Ambiente, Articulo 65 (1995).166 Numero 1.167 Numero 2.168 Numero 3.169 Numero 5.170 Numero 6.171 Reglamento para la Evaluación y Clasificación de la Calidad de Cuerpos de Agua Superficial, Capitulo 1, Articulo 1.172 Id. at Capitulo 1, Articulo 2.173 Capitulo I, Artículo 3(e).


Other MINAET actions include:

● setting the physicochemical and microbiological parameters for ordinary and hazardous wastewater.174 MINAET determined that the maximum permissible limits for phosphorous and nitrogen in residual waters is 25mg/L and 50mg/L, respectively;

● regulating the reuse of water175; ● defining different water uses176;● establishing a system of payments for the use of water, and in particular, the payment

for introducing or transporting contaminated substances that may modify the physical, chemical, or biological quality of the water. If there is a (1) point source spill, (2) the spill goes into a receptor body, and (3) the net spill is subject to one of the spill parameters established by MINAET, then one must pay a tax. If one of the three requirements is not met, then one will not be charged.177

Additionally, organized under MINAET are the Secretaria Tecnica Nacional Ambiental (SETENA) and Sistema Nacional de Area de Conservacion (SINAC). SETENA is principally responsible for developing Environmental Impact Assessment (EIA) procedures as well as assuring their proper use. SINAC is responsible for the conservation and sustainable development of natural resources within Costa Rica’s protected areas. The Tempisque River Basin (TRB) contains three such protected areas. The Comision de Implementacion y Desarrollo en la Cuenca Arenal Tempisque (CIDECAT) is also fundamental to an analysis of water quality in the TRB. With its more localized focus, the commission is made up of representatives from more than 15 governmental agencies, non-governmental organizations (NGOs), and private enterprises. Importantly, the Subcommittee on Water Quality monitors the Arenal Tempisque watershed. In addition to the Ministerio de Salud and SINAC (Area de Conservacion Arenal Tempisque—ACAT), the Instituto Costarricense de Acueductos y Alcantarillados (AyA), the Instituto Costarricense de Electricidad (ICE) play an important role. AyA was created in 1961 and reports to the Ministerio de Salud. Its mandate includes designing, financing, building, and operating water supply and sewage systems in both urban and rural Costa Rica. AyA also enforces the Ley General de Agua Potable, and plays a significant role in the conservation of water basins. Finally, the Instituto de Costarricense de Electricidad (ICE) may also be important in this analysis. ICE was created in 1949 to develop the electrical coverage in Costa Rica and recently has focused on several hydroelectric projects. Its largest reservoir, and also Costa Rica’s largest energy generator, is located in Lake Arenal, which supplies water to the TRB.

VII. Regulation in the United States: A Comparison with the Florida Everglades

174 Reglamento de Vertido y Reuso de Aguas Residuales.175 Id.176 Reglamento Canon por Aprovechamiento de Agua Potable.177 Reglamento de Creación de Canon Ambiental por Vertido.

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Once covering 11,000 square miles of Southern Florida, the Everglades ecosystem has undergone drastic anthropogenic changes in order to prevent floods and promote intensive agriculture. 178 These ecosystem shifts have increased nutrient loading into the historically nutrient poor wetlands causing significant damages, including water quality degradation.179 As a result, Florida has implemented various federal and state programs designed to decrease the negative impacts nutrients may have on its valuable watershed. Construction throughout the Tempisque River Basin, such as the Tempisque-Arenal Irrigation Project, mirrors the canals and large irrigation efforts that have consumed Florida and the Everglades.180 Coincidentally, both ecosystems are experiencing similar changes. For example, runoff from the Everglades has led to increasingly frequent harmful algal blooms in Florida Bay, and although uncertain to be correlated with increased nutrient inputs, Costa Rica’s Gulf of Nicoya has also been suffering from longer and more severe red tides.181 Thus, an overview of Florida’s successes and failures with its water quality legal framework may highlight programs that can facilitate sustainable development in Costa Rica’s Tempisque River Basin. Attention will focus on narrative and numeric water quality criteria, Total Maximum Daily Loads (TMDLs), Best Management Practices (BMPs), and Stormwater Treatment Areas (STAs).

a. Narrative and Numeric Water Quality Criteria In response to degrading water quality, Congress passed the 1972 Clean Water Act (CWA), which strives “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.”182 The Environmental Protection Agency (EPA) determined that the establishment of numeric nutrient criteria - measurable levels of the amount of nitrogen and phosphorus allowed into a specific water body - are necessary in order to meet the CWA’s goals.183 Due to a lack of funding required to develop biological measurements, however, Florida’s Department of Environmental Protection (DEP) has not implemented numeric nutrient criterion for all of its water bodies.184 Alternatively, the DEP has developed a narrative nutrient criterion that states, “In no case shall nutrient concentrations of a body of water be altered so as to cause an imbalance in natural population of flora and fauna.”185 Such criterion may be overly vague resulting in subsequent regulations and policies that do not appropriately reflect the needs of the ecosystem.

A component of water quality standards, these narrative and numeric water quality criteria are

178"Brief History of the Everglades." FDEP, 11 Feb. 2009. Web. 1 July 2012. <http://www.dep.state.fl.us/evergladesforever/about/default.htm>.179 Id. 180 Jimenez, Jorge A., Eugenio J. Gonzalez, and Javier Mateo-Vega. "Perspectives for the Integrated Management of The Tempisque River Basin, Costa Rica."Organization for Tropical Studies. 11-12. (2001).181 “Project Overview.” RSMAS, University of Miami. Web. 1 July 2012. <http://yyy.rsmas.miami.edu/groups/jmc/fla-bay/FBayOverview1.html>; Norman, Clayton R. “In Nicoya Gulf, the deadly red tide lingers.” Tico Times. 30 March 2012. Web. 1 July 2012. <http://www.ticotimes.net/Current-Edition/Top-Story/News/In-Nicoya-Gulf-the-deadly-red-tide-lingers_Friday-March-30-2012> 182 33 U.S.C. §1251(a) 183 “Frequently Asked Questions Related to Development of Numeric Nutrient Criteria.” FDEP, 21 Sept. 2011. Web. 1 July 2012. <http://www.dep.state.fl.us/water/wqssp/nutrients/faq.htm>184 Id. 185 Id.

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assigned to specific water bodies in order to protect the water bodies’ predetermined designated use - e.g. recreation, water supply, aquatic life, or agriculture.186 Additionally, existing water uses and high quality waters are maintained and protected through the process’s antidegradation policy.187 Ultimately, the water quality criteria are used to establish TMDLs.

b. Total Maximum Daily Loads (TMDLs) A TMDL is a complex calculation of the nutrient loading capacity for a specific waterbody. In other words, a TMDL is “the maximum amount of a pollutant that a waterbody can receive and still meet the water quality standards as established by the 1972 Clean Water Act.”188 The DEP is responsible for adopting TMDLs, which is a four step process in Florida: a particular waterbody is determined impaired, the waterbody is added to the verified list, a TMDL is created for the waterbody, and finally, a group of stakeholders creates a Basin Management Action Plan (BMAP) in order to implement the TMDL.189

Section 303(d) of the CWA requires Florida to provide a water quality report to the EPA every two years.190 These reports are used to determine whether a given waterbody should be added to the impaired waters list - a list of all waterbodies within that state that cannot attain or maintain applicable water quality standards due to insufficient pollution control measures. 191 Once the DEP has five years of data pinpointing pollutants contributing to the imbalance of flora and fauna, the waterbody will be added to the verified list.192

From here, the DEP develops a TMDL, which “shall account for seasonal variations and include a margin of safety that takes into account any lack of knowledge concerning the relationship between effluent limitations and water quality.”193 Once the TMDL is calculated, the DEP reasonably and equitably allocates the allowable nutrient loads among stakeholders, but these allocations will adjust during the subsequent BMAP procedure as more stakeholders are included.194

BMAPs have three beneficial implications. Firstly, BMAPs apply to point and nonpoint sources of nutrient loading, which subjects many agricultural producers to a regulatory framework for the first time.195 Secondly, BMAPs are intended to encourage “the greatest amount of cooperation

186“Overview of Impaired Waters and Total Maximum Daily Loads Program.” USEPA, 6 March 2012. Web. 1 July 2012. <http://water.epa.gov/lawsregs/lawsguidance/cwa/tmdl/intro.cfm>187 Id.188 Migliaccio, Kati W. and Brian J. Boman. “Total Maximum Daily Loads and Agricultural BMPs in Florida.” Institute of Food and Agricultural Sciences, University of Florida. 1. (May 2009).189 Hamann, Richard. “Managing Nutrient Inputs to Florida Springs: The Legal Framework.” Center for Governmental Responsibility, Levin College of Law, University of Florida. 306.190 “Fact Sheet: Introduction to Clean Water Act (CWA) Section 3030(d) Impaired Waters Lists.” USEPA, Office of Water. 17 July 2009. Web. 1 July 2012. <http://www.epa.gov/owow/tmdl/results/pdf/aug_7_introduction_to_clean.pdf> 191Id. 192 Hamann, Richard. “Managing Nutrient Inputs to Florida Springs: The Legal Framework.” at 317.193 Fla. Stat. § 403.067(6)(a)(2) (2011). 194 Id. § 403.067(6)(a)(2)(b) (2011).195 Id. § 403.067(7)(a)(2) (2011); Hamann, Richard. “Managing Nutrient Inputs to Florida Springs: The Legal Framework.” at 318.

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and consensus possible”, an objective that will likely lead to more effective and continual practices.196 Lastly, the BMAP procedure incorporates adaptive management by requiring milestones for implementation, water quality monitoring plans, and continual progress updates conducted every 5 years.197

c. Best Management Practices (BMPs) In order to comply with pollution reductions allocated in the BMAP, nonpoint nutrient dischargers must either implement BMPs or establish water quality monitoring as prescribed by the DEP or water management district to prove discharges meet state water quality standards.198 BMPs are defined as “a practice or combination of practices determined by the coordinating agencies, based on research, field-testing, and expert review, to be the most effective and practicable on-location means, including economic and technological consideration, for improving water quality in agricultural and urban discharges.”199 Although DEP is responsible for establishing TMDLs generally, the Florida Department of Agriculture and Consumer Services (FDACS) establishes TMDLs specifically for agricultural nonpoint source pollution. These institutions have partnered with the Institute of Food and Agricultural Sciences (IFAS) at the University of Florida in order to develop commodity and regionally specific BMP manuals.200 Because the Tempisque River Basin is primarily dominated by agricultural activities, an overview of the Everglades Agricultural Area (EAA) BMP program is most relevant to this discussion. The EAA contributes a significant amount of nonpoint nutrient loads into south Florida’s watershed, and the South Florida Water Management District (SFWMD) has developed a BMP program for the area in order to reduce phosphorus levels in drainage waters by a least 25% relative to historic levels.201 One focus of the EAA’s BMP program is reducing sediment and water runoff because of its potential to carry nutrients, particularly phosphorus, with it to areas further downstream. One way to reduce runoff is by leveling the fields prior to planting the crops. This limits the potential for soil erosion after heavy rainfalls and improves field drainage and irrigation efficiency. Ditch and canal bank berms prevent excess sediments and runoff from directly entering drainage canals by forcing the excess water to pond on the surface of the field. This

196 Fla. Stat. § 403.067(7)(a)(3) (2011).197 Id. § 403.067(7)(a)(5) (2011).198 Florida is divided into five water management districts in order to facilitate more localized governance of watershed issues as well as improve site-specific water quality monitoring. Additionally, it is important to note that point source pollution discharges require National Pollution Discharge Elimination System (NPDES) permits, but because the Tempisque River Basin is dominated mainly by agricultural areas and nonpoint source discharges, discussion on NPDES permits is not addressed in this paper. Fla. Stat. § 403.067(b)(2)(g) (2011). 199 Migliaccio, Kati W. and Brian J. Boman. “Total Maximum Daily Loads and Agricultural BMPs in Florida.” at 2.200 Id. 201 Diaz, O.A., Lang, T.A., S.H. Daroub and M. Chen. “Best Management Practices in the Everglades Agricultural Area: Controlling Particulate Phosphorus and Canal Sediments.” Institute of Food and Agricultural Services, University of Florida. 1. (March 2012).


way, the excess nutrients may percolate vertically into the soil. This same berm technique may be used near roads, preventing residual fertilizers on the roads from dumping directly into nearby canals.202

An additional 60-90% of sediment may be removed by implementing sediment sumps and traps into the field ditches and drainage canals.203 Sediment sumps may also be constructed in the field ditches. The canals and field ditches should be cleaned regularly or else the nutrient-rich sediment that has accumulated may be transported elsewhere throughout the watershed without proper treatment. Cleaning and irrigation times should be coordinated in order to recycle the nutrient- rich sediment into the system further upstream.204 BMP programs often suggest that vegetation be used to minimize nutrient inputs. One way is through the use of cover crops - “a crop grown to provide soil cover to minimize soil loss to erosion” when a field would ordinarily be left unplanted or unprotected.205 Specifically, flooded field crops, such as rice, are effective at reducing soil losses due to wind and water erosion. Ditch banks can be vegetated with plant species that have extensive root systems in order to prevent bank erosion.206 Lastly, perimeter borders - vegetation established around an entire field - “provide a barrier...that results in less erosion and greater water infiltration which benefits both agricultural production and the environment.”207 Native plant species will limit perimeter border maintenance. Although most vegetation assists in nutrient removal, floating aquatic weeds contribute directly to nutrient export downstream and should be aggressively eliminated through the installation of weed booms or trash racks.208

When an agricultural producer implements BMPs, they are legally presumed to be in compliance with state water quality standards.209 This protection from liability to the state when water quality standards are not met functions as an incentive for agricultural producers to adopt BMPs, but such a presumption can also result in toothless regulation. Additionally, BMPs are rarely inspected to ensure compliance. For instance, only 5 engineers are available to conduct BMP inspections for the entire EAA, which is approximately 450,000 acres, and many individuals’ farms fail to consistently comply with their BMP obligations although the entire EAA may meet its nutrient input goals. Thus, although BMPs assist in decreasing nutrient inputs into the Everglades, their full potential has yet to be realized.210

d. Stormwater Treatment Areas (STAs)

202 Id. at 1-2; See Appendix II, figure 1.203 Id. at 3; See Appendix II, figure 2.204 Id. at 4.205 Id. at 4-5.206 Id. at 5-6.207Migliaccio, Kati W., Boman, Brian, Jemy Hinton and Kevin Hancock. “Best Management Practices (BMPs): Perimeter Borders.” Institute of Food and Agricultural Services, University of Florida. 1. (Jan. 2012).208 Diaz, O.A., Lang, T.A., S.H. Daroub and M. Chen. “Best Management Practices in the Everglades Agricultural Area: Controlling Particulate Phosphorus and Canal Sediments.” at 6; See Appendix IV, Figure 3.209 Fla. Stat. § 403.067(7)(c)(3) (2011).210 “Improved BMPs and Source Controls needed in the EAA.” Audubon of Florida. Aug. 2011. Web. 1 July 2012. <http://audubonoffloridanews.org/wp-content/uploads/2011/08/EAA-BMP-Revision-paper-August-2011.pdf>


While BMPs regulate agricultural activity, STAs are projects designed to filter nutrients once they leave the crop fields. Funded by taxpayers, these constructed treatment wetlands “remove and store nutrients through plant growth and the accumulation of dead plant material in a layer of peat.”211 The agricultural runoff south of the EAA is treated extensively by STAs in order to improve the quality of water bound for the Everglades. The SFWMD began to implement the STAs after the Florida state legislature passed the Everglades Forever Act (EFA) in 1994.212 Pursuant to the Act, DEP is responsible for protecting and restoring the Everglades using the “best available technology,” which includes the combined implementation of BMPs and STAs.213 Although both BMPs and STAs have been implemented, some argue STAs may be overloaded and underperform as a result of toothless BMPs.214

VIII. Recommendations for Revised Regulatory Structure for Nutrient Management in

the Tempisque

a. Recommendation 1: Student Monitoring and Sampling Design, and Water Classification

The most necessary action to address the potential of nutrient issues within the Tempisque River Basin is to begin with a bottom-up approach in order to implement water quality monitoring by incorporating all relevant stakeholders. A monitoring and sampling scheme should be created in order to determine if various land uses are discharging nutrient pollution to water bodies within the TRB as well as the relative proportion of discharge compared to other sources. This can be done by sampling at the inflows and outflows of crop lands, ranch lands, industries, and residential areas. In regards to funding this strategy, SENARA could team up with the Universidad de Costa Rica and Organization of Tropical Studies in order to begin implementation of such a program. This approach is similar to the way the University of Florida’s Institute of Food and Agricultural IFAS, the South Florida Water Management District, and others have joined. Suggestions for implementation of a monitoring program include:

● A sampling scheme should be created that includes reference locations representative of each land use within the Tempisque River Basin.

● Samples should be taken regularly at the beginning and end of each reference site over an extended period of time in order to determine relative discharge to water bodies.

● Samples should be taken at the confluence of the Tempisque River and Gulf of Nicoya as well as each tributary of the Tempisque River.

● Seasonal and temporal variations should be incorporated into the sampling design.● More extensive monitoring of the upwelling in Gulf of Nicoya should be done in order to

determine the flux of nutrients carried into the upper and lower Gulf regions.

211 “Stormwater Treatment Areas: Managed wetlands improving Everglades water quality.” SFWMD. 2012. Web. 1 July 2012. <http://my.sfwmd.gov/portal/page/portal/xrepository/sfwmd_repository_pdf/bts_sta.pdf> 212 Id.213 Fla. Stat. § 373.4592(1)(g) (2010). 214“Improved BMPs and Source Controls needed in the EAA.” Audubon of Florida. at 1.


MINAET has defined five different classes of water based on the Dutch classification index.215 This classification system identifies water bodies based on water quality parameters. Opposing this the U.S. water body classification system focuses on human use of the water and sets standards based on the classification. It is recommended that the Tempisque Basin assign water quality standards based on land and water use. Likewise, it is recommended to add a phosphorus component to the classification scheme which is currently missing from the current MINAET classification system.

b. Recommendation 2: Create BMP Implementation Program as Prevention Tool Costa Rica exudes an image of a country that has adopted strict environmental policies in order to pave a future for sustainable development. To maintain this image, Costa Rica has the opportunity to employ the precautionary principle by immediately implementing BMPs without the scientific certainty of a nutrient problem. Such implementation should work from the bottom-up and include all stakeholders. Initial BMPs could be implemented from those suggested in the IFAS EAA manual, but as more area-specific nutrient data is developed, SENARA and MINAET can work with EARTH University and the Universidad de Costa Rica in order to develop regionalized and localized BMP programs. However, BMPs should not be forced onto the local populations. Instead, information about BMPs and the potential impacts of nutrient loading on the Tempisque River Basin should be disseminated to all local stakeholders. Thereafter, well-informed and deliberative meetings can be held on whether or not to implement BMPs and which ones should be implemented by whom. Although voluntary, community members will likely be motivated to implement BMPs because they will have an opportunity to influence policy-making and take part in creating their own regulations. Additionally, community members may be incentivized to act because it will cost them less money in the long-term if a nutrient loading problem is discovered. By implementing precautionary BMPs, the resources necessary to establish TMDLs may be avoided.

c. Recommendation 3: Implementation of TMDLs and BMPs within Regulatory Framework

MINAET and SENARA establish TMDLs according to the water classifications as defined by the Reglamento para la Evaluación y Clasificación de la Calidad de Cuerpos de Agua Superficiales. The TMDLs will determine how much can be discharged into a waterbody without changing classifications. After TMDLs are established, mandatory BMPs will be implemented. Like the United States, once BMPs are implemented the participants compliance will be presumed. Despite the incentive to comply, however, under this system there is a lack of enforcement power. Also, time and money must be expended creating the TMDLs.

d. Recommendation 4: Implement Stormwater Treatment Areas (STAs)

215 Reglamento para la evaluacion y clasificacion de la calidad de Cuerpos de Agua Superficiales - Capitulo II. Art. V. Cuadro 1


Stormwater treatment areas function to clean up nutrient-rich water once it has already been introduced into the ecosystem. Because rice functions to reduce nutrient runoff, future land use decisions may be made in order to promote rice production towards the downstream portion of the agricultural area. Unlike the Florida STAs, no additional taxpayer capital is not spent on creating wetlands but rather on promoting rice fields. Because many rice fields are already located downstream additional constructed wetlands can be placed at the end of the agricultural area to remove the excess nutrients.

e. Recommendation 5: No Action

A “wait and see” approach could continue to be followed. The assumptions of this strategy would be that there is no nutrient problem in regards to nutrient pollution and transport along any length of the Tempisque Basin or upper Gulf of Nicoya. This strategy also assumes that it is unlikely that there will be an issue in the future despite continued intensive agriculture and population growth. Although this strategy requires no funding for prevention measures now, if negative impacts do occur in the future more substantial amounts of funding may be required.

Figure 3. Diagram of Recommendations 1-4 in regards to nutrient management in the Tempisque River basin.


IX.Appendix I - Everglades Land Use Map and Visual Diagrams of Best Management

Practices

Figure 1. Schematic diagram of A) field ditch berm and B) main canal bank berm.216

216 Diaz, O.A., Lang, T.A., S.H. Daroub and M. Chen. “Best Management Practices in the Everglades Agricultural Area: Controlling Particulate Phosphorus and Canal Sediments.” Institute of Food and Agricultural Services, University of Florida. 2. (March 2012).


Figure 2. Schematic diagram of Above) Field Ditch Sump and Below) Sediment Sumps and Traps in Drainage Canal.217

217 Id. at 3.


Figure 3. Image of a weed boom to help keep aquatic weeds from entering main drainage canals.218

218 Id. at 6.

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