integrating water-quality management and land-use planning in a watershed context
TRANSCRIPT
Journal of Environmental Management (2001) 61, 25–36doi:10.1006/jema.2000.0395, available online at http://www.idealibrary.com on
Integrating water-quality managementand land-use planning in a watershedcontext
X. Wang
The spatial relationships between land uses and river-water quality measured with biological, water chemistry,and habitat indicators were analyzed in the Little Miami River watershed, OH, USA. Data obtained fromvarious federal and state agencies were integrated with Geographic Information System spatial analysisfunctions. After statistically analyzing the spatial patterns of the water quality in receiving rivers and landuses and other point pollution sources in the watershed, the results showed that the water biotic quality didnot degrade significantly below wastewater treatment plants. However, significantly lower water quality wasfound in areas downstream from high human impact areas where urban land was dominated or near pointpollution sources. The study exhibits the importance of integrating water-quality management and land-useplanning. Planners and policy-makers at different levels should bring stakeholders together, based on theunderstanding of land–water relationship in a watershed, to prevent pollution from happening and to planfor a sustainable future. 2001 Academic Press
Keywords: water quality, land-use planning, watershed management, Geographic InformationSystems, Index of Biotic Integrity, Invertebrate Community Index.
Introduction
Industrialization and urbanization havebrought prosperity, and at the same time,also have resulted in many environmentproblems. It has been recognized that thequality of receiving waters is affected byhuman activities in a watershed via pointsources, such as wastewater treatmentfacilities, and non-point sources, such asrunoff from urban area and farm land.Although researchers have paid particularattention to the effect of land use on waterquality (Lenat and Crawford, 1994; Hallet al., 1994), a water-quality component oftenis missing in land-use plans and land-useplanning is rarely used in water-qualitymanagement. This could be due to the factthat water-quality management and land-use planning often are administrated bydifferent agencies that do not coordinateconstantly. Most planning agencies and local
Email of author: [email protected]
School of Planning,University of Cincinnati,Cincinnati, OH45221-0016, USA
Received 19 April 2000;accepted 5 October 2000
authorities do not have resources to collectextensive land use and water-quality data indeveloping plans (Wang and Yin, 1997) andwater-quality management agencies tradi-tionally address existing water-quality prob-lems rather than preventing them.
Water quality refers to the physical, bio-logical and chemical status of the waterbody. Streams and rivers are typically diverseand biologically productive environments intheir natural form. The presence, abundance,diversity and distribution of aquatic speciesin surface waters are dependent upon a myr-iad of physical and chemical factors, suchas temperature, suspended solids, pH, nutri-ents, chemicals, and in-stream and riparianhabitats. Until recently, the dominant meth-ods of evaluating water quality are based onwater chemical and, to some extent, physicalproperties. Studies have found that biologicalimpacts from non-point sources and habitatdegradation may not be fully represented bythe periodical measurements of the physi-cal–chemical characteristics of water bodies.
0301–4797/00/010025C12 $35.00/0 2001 Academic Press
26 X. Wang
For example, the Ohio Environmental Protec-tion Agency (OEPA) used both water chem-istry and biological indicators to evaluatewater quality and discovered that the amountof impaired waters was twice the amount ifchemical indicators were used alone (OEPA,1988). To detect the effects of human activ-ities which were missed or underestimatedby the conventional physical-chemical indica-tors, methods of biological assessment weredeveloped in the 1970s and early 1980s(Norris and Norris, 1995; OEPA, 1987, 1989).Biological assessment of water quality isbased on the assumption that a water bodywith biological integrity should have theability to ‘support and maintain a balanced,integrated, adaptive community of organ-isms having a species composition, diver-sity, and functional organization compara-ble to that of the natural habitats withina region’ (Karr and Dudley, 1981). There-fore, those water bodies that have beenimpacted by human activities to variousdegrees should demonstrate changes in bio-logical integrity. Since the US EnvironmentalProtection Agency (USEPA) issued guide-lines for state environmental protection agen-cies to develop and implement biologicalassessment of surface-water quality (USEPA,1990), biological assessment has been usedin various aquatic environments, such asstreams, lakes and estuaries. Various organ-isms including fish, insects, macroinverte-brates, and algae (especially diatoms) havebeen used in these studies, using popula-tion size, species composition or communitystructure, and various activities as indicatorsof water quality (Angermier and Karr, 1986;Elnaggar et al., 1997). Biological assessmentof water quality has proven to be a useful com-plementary tool to the conventional physical-chemical assessment for a wide variety ofhuman impacts, including urban develop-ment (Khan, 1991; Norris and Norris, 1995).OEPA has been a leader in creating biolog-ical criteria as the operative standards forevaluating water-quality status by develop-ing Index of Biotic Integrity (IBI) for fishcommunities and Invertebrate CommunityIndex (ICI) for invertebrates.
Although the impacts of human activi-ties on environment have been discussedand debated extensively within conceptualand moral contexts, there is much need formore empirical analyses. This paper presents
a study exploring the spatial dependenceof water quality measured with waterchemistry, biological and habitat indicatorsand land uses, using spatial statistical anal-yses based on Geographic Information Sys-tems (GIS), in the Little Miami River (LMR)watershed, OH. After examining the com-plexity of water-quality indicators and therelationship between the quality of receivingrivers and land uses in the watershed, the sig-nificance of integrating water-quality man-agement and land-use planning is discussed.Although the data availability limits the sizeof data set used in the study, the resultsreveal some patterns that are too significantto be ignored in watershed management.
Study-area
The Little Miami River watershed is locatedin southwest Ohio, adjacent to the greatermetropolitan Cincinnati area (Figure 1). TheLMR drains an area of 4550 square kilo-meters and has a main stem length of170 km. The northern half of the watershedis located in the Eastern Corn Belt Plainsecoregion (Omernik, 1988), which is charac-terized by level to gently sloping land. Coarseglacial deposits (e.g. gravel, cobble, and boul-ders) dominate substrates in this region. Thesouthern half of the watershed is located inthe Interior Plateau ecoregion and is char-acterized by higher gradient streams withbedrock (limestone and shale) substrates.According to the land-use data compiled bythe Ohio Department of Natural Resources(ODNR), the LMR watershed is primarilydominated by cropland and pasture (71Ð0%).The second largest land use is wooded area(22Ð8%) with the urban land as the third(4Ð2%). The largest urban areas in the water-shed are on the western side, which forms theeastern boundary of the growing metropoli-tan areas from Dayton to Cincinnati, OH.The LMR watershed contains a major recre-ational area and the most rapidly growingpart of the state of Ohio. During the periodfrom 1990–1997, population in four of thefive counties which make up the majorityof the LMR watershed increased by a rangeof 15–25%, compared to state wide increaseof only 3Ð1%. Projected population growth inthis area will take the Cincinnati StandardMetropolitan Area (SMA) to over 2 000 000
Water-quality and land-use planning 27
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BUTLER
BROWN
HIGHLAND
FAYETTE
MADISONCLARK
Springfield
GREENE
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LITTLE M
IAMI R
CAESAR CR
LITTLE M
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I R T
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CLINTON
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CLERMONT
HAMILTON
LITTLE M
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kilometers
Dayton
MONTGOMERY
Cincinnati
Figure 1. Study area: Little Miami River Watershed, OH, USA. Little Miami River (. . .); Little Miami RiverBarin (—); urban area, .
by the year 2000. As a result, developmentpressure in the basin is extreme.
The LMR is a designated National andState Scenic River as well as an ExceptionalWarmwater Habitat. The river is biologicallydiverse in fish, mussels, macroinvertebrates,and algae. An OEPA study indicated thatalthough total annual loading from pointsources has reduced since 1983 with waste-water treatment plant (WWTP) upgrades thecumulative total amount of pollutants stillexceeds the assimilative capacity of the LMRon the upper river. Signs of stress are evidentin higher rates of deformities, fin erosion,lesions, and external tumors, known as DELTanomalies in fish; and high soluble reactivephosphorus (SRP) in the river segmentsdominated by WWTP effluents (OEPA, 1995).
Data
This study analyzed hydrographic, land usesand water-quality data from various sources
Table 1. Data and data sources
Data type Data collection Datatime source
Water chemistry 1992–1996 USEPAFish (IBI) 1993 OEPAMacroinvertebrate (ICI) 1993 OEPARiver habitat (QHEI) 1993 OEPAIFD sites 1992 USEPATRI sites 1987–1995 USEPAWWTP discharge points 1988 USEPA1:100 000 scale 1994 USEPA
river networkLand use/land cover 1994 ODNR
(25-m resolution)
as shown in Table 1. The water chemistrydata were from STORET, a uniform data col-lection and reporting system maintained byUSEPA, containing data describing surfaceand ground water quality for North Americanwaterways (USEPA, 1992). Conventional pol-lutant data for the watershed were retrievedfor 1992–1996 to ensure compatibility withbiological and habitat data (collected in 1993).The indicators include dissolved oxygen
28 X. Wang
(DO), pH, total suspended solids (TSS530),nitrogen-total ammonia (NH3), total organiccarbon (TOC), and hardness. Those variableswere selected from commonly used indica-tors based on the data availability in thestudy area. Point pollution source data wereretrieved from three different sources. Dis-charges from WWTPs, including municipalplants and small, privately owned treatmentworks, were retrieved from the 1988 USEPANeeds Survey (USEPA, 1989). The Indus-trial Facilities Discharge (IFD) sites wereobtained from a USEPA database, updatedin 1992, containing facility information onindustrial point source discharges to surfacewaters (USEPA, 1998). Toxic Release Inven-tory (TRI) sites were obtained from a USEPAdatabase maintaining facility informationfor 1987–1995 TRI public data (USEPA,1998).
Habitat, fish, and macroinvertebrate datacollected during an intensive 1993 LMRsurvey were provided by the OEPA (Dyeret al., 1998a). IBI was first developed from12 metrics that reflected fish species richnessand composition, number and abundance ofindicator species, trophic organization andfunction, reproductive behavior, fish abun-dance, and condition of individual fish (Simonand Lyons, 1995). Ten metrics were used toconstruct ICI for invertebrates. The Qual-itative Habitat Evaluation Index (QHEI),which was derived from six metrics, pro-vided a multi-parameter physical habitatstatus of rivers and riparian areas (Rankin,1989).
The land-use/land-cover data, obtainedfrom ODNR, were extracted from the Ohio1994 statewide land-cover inventory. Theinventory was produced from Thematic Map-per data acquired in September and October1994 at a 25-m resolution. The data wereclassified into seven general land-cover cat-egories: urban, agriculture, shrub, wooded,open water, non-forested wetlands, and bar-ren. The digital hydrographic data werebased on USEPA’s reach file version 3,RF3, a hydrological database of the surfacewaters of the US in ARC/INFO line cov-erage format. The database contains morethan 3Ð2 million records encompassing allUS streams (e.g. unnamed rivers and head-waters) at a scale of 1:100 000 (Dyer et al.,1998a).
Spatial integration
Biological, chemical and habitat monitoringsites rarely occurred at the exact samelocations. To relate data from these sites ina spatially meaningful way, those sites wereassociated to river segments spatially. Therivers were first divided into segments in away that WWTP discharges and confluencesof major tributaries (generally greater thanthe first order tributaries) were used toseparate two adjacent segments. Then eachsegment was assigned a unique identifier.The GIS spatial overlay functions were usedto connect the river segments to the waterquality monitoring sites based on the nearestdistance. The result was that each monitoringsite had a unique river segment number.Those monitoring sites with the same riversegment number were treated as within thesame geographic unit. Detailed discussions ofriver segmentation and overlay analysis canbe found in Dyer et al. (1998a,b).
Twenty-two catchments for river segmentsnear headwaters and with water quality mon-itoring data were delineated and digitized inreferencing to the river network. Only theheadwater catchments were used in the land-use analysis so that the catchments werespatially independent to each other. Thosecatchments were overlaid with the land usedata to derive land use make-up for eachcatchment, using the ArcView Spatial Ana-lyst Extension. The area and percentage ofland uses were calculated for each catch-ment. Figure 2 displays the catchments andland use compositions. Mean water qualitydata values were calculated from multiplemonitoring sites in the same catchment.
Two classification schemes were used togroup the water quality monitoring sites.The first scheme separated the monitoringsites into two groups according to theirlocation to WWTPs. The first group includedthose sites that were in the river segmentsupstream from WWTPs and the other groupincluded those sites that were in the riversegments downstream from WWTPs. Thesecond scheme separated the monitoringsites according to their proximity to pointsources and urban land. The first groupincluded those sites that were either locatedin high human impact areas, including riversegments in urbanized area or immediately
Water-quality and land-use planning 29
N
10 0 10
kilometers
Figure 2. Land-use composition in selected catchments. Land-use composition: Urban ; agriculture ;shrub scrub ; wooded . Other types of land use, not shown on the figure due to their small percentages,are: open water, non-forested wetlands and barren. Little Miami River (. . .); watershed boundary (—).
30 X. Wang
downstream from a point pollution source,which could be a WWTP, an IFD or a TRIsite. All other monitoring sites were includedin the second group, which represents the lowhuman impact areas.
Statistical analysis
Several statistical analyses were used toanalyze the spatial distribution patternsof habitat, land uses, and water qualitymeasured with water chemistry, Fish (IBI),and Macroinvertebrate (ICI) indicators, inthe study area. First, measures from thesites that were immediate upstream fromWWTPs were compared with measures fromsites that were immediate downstream fromthe same WWTPs with a paired t-test methodto test the hypothesis that water qualitydecreased below WWTP discharge points.Further, an independent two-sample t-testwas performed to test the hypothesis thatwater qualities of river segments in highhuman impact areas were worse than that ofriver segments in low human impact areas.
Finally, biological, habitat, and waterchemistry monitoring values from the riversegments and land use distribution withincorresponding catchment were analyzedusing the Pearson’s correlation to revealany possible relationships between biologicalindicators and land uses and riparian habitatindicator. Multiple regression was then usedto determine the principle driving forcesfor biotic integrity within the LMR (Dyeret al., 1998a). The purpose of the analysisis to evaluate the strength of the impactof land uses on the quality of receivingwaters. Several water-chemistry parametersthat had very small sample sets or weredominated by detection limit were droppedfrom the analysis.
Results and discussion
The results of this study are presented anddiscussed from three aspects—the impactof wastewater treatment plants, the spatialpatterns of river-water quality, and therelationship between land uses in catchmentsand water quality of the receiving water. Theimportance of considering water quality in
land-use planning is discussed based uponthe findings from this study.
Impact of wastewater treatmentplants
Table 2 displays the results from a pairedt-test of the IBI, ICI, and QHEI in refer-ence to WWTP discharge points. The IBImeasurement from the closest sites to thedischarge points demonstrated a statisticallysignificant decrease of water quality down-stream from WWTP discharges. Althoughboth ICI and QHEI demonstrated similartrend, the change was not statistically sig-nificant. This implies that the water qualitymay not change significantly below and aboveWWTP discharge points. The lack of strongimpact may be attributed to the better munic-ipal WWTP practices (OEPA, 1995). Theresult concurs with findings by others thatimproved management of sewage reduced theimpact on receiving waters (Wichert, 1995;Frenzel, 1990). The result also suggests a fur-ther study to analyze the discrepancy of thesensitivities of fish indicators (IBI) and inver-tebrate indicators (ICI) to WWTP discharges.
Spatial patterns of water quality
A visual examination of spatial distributionsof the urban land use shows that thereare two major urban areas within the LMRwatershed. One is near the basin outletat the lower left portion of the watershedand another is at upper left. In addition,there are a few smaller settlements scat-tering within the watershed (Figure 3). Itis noticed that various types of point pollu-tion sources are also concentrated in or nearthe more urbanized areas. A t-test of the
Table 2. Matched-pair t-test of water quality fromupstream and downstream of WWTPs
Variable Paired differencesa t df Significance
Mean SD (1-tailed)
IBI �4Ð769 9Ð471 1Ð816 12 0Ð0472Ł
ICI �1Ð000 7Ð886 0Ð439 11 0Ð3345QHEI �1Ð875 20Ð190 0Ð256 11 0Ð3770
aPaired difference is calculated as downstream monitoringvalue minus upstream monitoring value for the sameWWTP.
Water-quality and land-use planning 31
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Figure 3. Urban land and point pollution sources. Industrial facility discharge sites (Ł); wastewater-treatment plants ( ); toxic release inventory sites ( ); Little Miami River (. . .); watershed boundary ( ).
mean monitoring values from the sites in thehigh and low human impact areas was per-formed upon the three indicators (Table 3).Both IBI and ICI values demonstrated signif-icantly lower values in high human impactareas. It was interesting to note that habitatsalso showed lower quality in those areas, asindicated by low QHEI scores. These resultsimply that the biological integrity in rivers
flowing through high human impact areastend to be lower.
Land uses and water quality of thereceiving waters
Among the 22 catchments, urban landpercentages varied from 1% to 58% and
32 X. Wang
Table 3. Independent t-test on the water monitor-ing data in LMR watershed
Para- High human Low human t pa
meter impact area impact area
Mean N Mean N
IBI 33Ð27 77 44Ð50 68 �8Ð625 5Ð55E-15b
ICI 34Ð94 36 43Ð77 35 �3Ð288 0Ð0008b
QHEI 62Ð45 73 73Ð77 61 �5Ð869 1Ð67E-08b
aSignificance level or the less-than and equal-to probabilityof the t value.bSignificant at the 0Ð05 level.
agricultural-land percentages varied between12% and 95% (Figure 2). The IBI and ICIhave similar relationships to habitat quality(QHEI) and land uses although the levelsof significance vary (Table 4). These bio-logical indicators are negatively related tothe percentages of urban land use and posi-tively related to agricultural land use. Theyalso are positively related to habitat qual-ity. The correlation analysis showed that at0Ð05 significant level the IBI scores weresignificantly correlated with percentage ofurban land use (�0Ð59) and agriculturalland use (0Ð53). IBI was also positively cor-related with QHEI (0Ð67). The correlationsbetween ICI and QHEI and land uses werenot statistically significant. The results sug-gest that IBI may be a more sensitive toland-use composition and riparian-habitatquality.
Table 4. Pearson product movement correlationcoefficients
Land use and habitat IBI ICI
UrbanPearson correlation �0Ð59a �0Ð22Significance (2-tailed) 0Ð00 0Ð40Sample size 22 16
AgriculturePearson correlation 0Ð53a 0Ð30Significance (2-tailed) 0Ð01 0Ð26Sample size 22 16
WoodedPearson correlation �0Ð27a �0Ð28Significance (2-tailed) 0Ð23 0Ð30Sample size 22 16
QHEIPearson correlation 0Ð67a 0Ð41Significance (2-tailed) 0Ð00 0Ð11Sample size 22 16
aCorrelation is significant at the 0Ð05 level (2-tailed).
In a previous study Dyer et al. (1998a)applied a multivariate forward stepwiseregression model to determine the relativeimportance of water chemistry and habitaton biological indicators in the Little MiamiRiver watershed. Their study concluded thatthe habitat quality was primarily responsiblefor the biological integrity of receiving watersin the watershed. A similar regression anal-ysis was conducted in this study on the 22selected catchments. Percentages of urbanand wooded land uses by catchment wereincluded in the multiple regression analysis,in addition to the habitat and water chem-istry indicators used in Dyer et al. (1998a).The percentage of agricultural land was notincluded because it was highly correlatedwith the percentage of urban land. Otherindependent variables were the six waterchemistry variables—dissolved oxygen, pH,total suspended solids, nitrogen-total ammo-nia, total organic carbon, and hardness, andQHEI. The dependent variables were IBI andICI, respectively. Figure 4 shows the scatterplots of the predicted values against mea-sured values for IBI and ICI, respectively.The results shown in Table 5 indicate thatthe land-use components within the catch-ments could be major predictors for bioticintegrity. The percentage of urban land wasthe second strongest predictor for both IBIand ICI. The negative signs of those coeffi-cients indicate that as the intensity of humanactivities increase there is a tendency that thebiological integrity of the rivers decreases.The percentage of wooded land was the thirdstrongest predictor for IBI. The positive signof the coefficient shows that higher river bio-logical quality may be expected in areas ofless intensity of human impact. When theresults for the two dependent variables, itappears that the independent variables canexplain IBI better than ICI.
Water quality consideration inland-use planning
This study exhibits the complexity of waterquality indicators and their spatial distribu-tion. Such complexity implies that differentindicators often reflect different aspects of awater body and the status of water qualitymay be affected by many factors in differentways. Although water chemistry in the Little
Water-quality and land-use planning 33
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Figure 4. Comparison of predicted and measuredbiological indicator values. (a) Dependent variable:IBI; (b) dependent variable: ICI.
Miami River was at good condition (severalof the water chemistry variables were ator below detection limit, which might havecontributed to the fewer data available forthe analysis), biotic indicators have pickedup some effects of human activities on thereceiving water. The t-test showed that urbanland and point sources (WWTPs, IFDs, andTRIs) together might explain the lower bioticquality throughout the watershed. This find-ing confirms that one of the greatest causes
of water-quality problem derives from urbanland use as a result of the increasing intensityof human activities. Pollution has resulted inloss of species diversity within rivers (Hay-cock and Muscutt, 1995).
The hydrological relationship betweenwater systems and the land requirescoordination between the water managementand land management fields. Once theland–water relationship is identified, itleads to the need of protecting waterquality through proper land-use planning byidentifying cost-effective pollution preventionand pollution correction approaches thatcan address all the sources of pollutionin a comprehensive way. To take suchchallenge, it is necessary to look intowater-quality management and land-use-planning practices and draw the connectionbetween the two. By tradition, water-quality management and land-use planningare implemented by different agencieswith different objectives. The purpose ofwater-quality management is to maintainand improve ambient water quality,which requires designation of waterusage, establishment of criteria to protectdesignated uses, and development of water-quality management plans accordingly.The objective of land-use planning is tomaximize the uses of land by humanswhile minimizing the negative impact tohumans’ health and welfare. Land-useplanning, after systematically analyzingdifferent alternatives and the need forland use changes, determines future landuses, improves physical conditions for theplanned land uses, and manages activitiesassociated with the planned land uses (vanLier, 1998). In practice, land-use planningis often fragmented temporally and spatiallysince most land-use plan is often producedfor area within a political boundary and
Table 5. Results of forward stepwise multiple regression analysis
Dependent variable IBI ICI
Adjusted R2 0Ð934 0Ð773
CoefficientConstant �16Ð823 �2Ð345Predictor 1 QHEI 0Ð761 Hardness 0Ð058Predictor 2 % of Urban land �45Ð078 % of Urban land �81Ð472Predictor 3 % of Wooded land 35Ð194 Dissolved oxygen 3Ð793
Use probability of F less than or equal to 0Ð1 for inclusion of the independent variables (predictors)and the coefficients are different from zero at 0Ð5 significance level.
34 X. Wang
only to serve the community which adoptthe plan. In the United States, land-useplanning is implemented at local communitylevel (municipal or county) (Thomas andFuruseth, 1997) and consequently non-localinterests are not considered equally in land-use planning decision-making. For example,typical land-use suitability and feasibilityanalyses often are limited to the proposedproperty and immediately surrounded areas.Water-quality issue is usually not sufficientlystudied in land-use planning.
The impact of urban land uses on riverwater quality demonstrated in this studysuggests that the known land–water rela-tionship is significant enough for plannersand decision-makers to pay proper atten-tion to water-quality issues in evaluatingplans and facilitating collaborations. Achiev-ing the sustainable management of waterand land resources could be a major con-sideration in exploring planning alterna-tives within a watershed. After realizing thewater-quality problems related to non-pointsources and the loss of aquatic habitat, theUS EPA has been promoting an ecological-based watershed protection approach (WPA)(Brady, 1996). The WPA delineates a geo-graphic area based on its natural character-istics—a watershed—and the stakeholderswhose activities are on water or land withinthe watershed are involved in defining prob-lems, set priorities, and implement solutions(Davenport et al., 1996). The LMR studyshows that the WWTPs alone may not sig-nificantly affect the water quality while thecombined affect from point sources (WWTPs,TRIs, IFDs) and non-point sources (urbanland) can be reflected in the water-qualitydata. At present, only point sources are reg-ulated by environmental agencies such asOEPA in LMR watershed while non-pointsources are unregulated. This study resultshows that such management may not beeffective in water quality protection. Thefinding reinforces the notion that manage-ment of point and non-point sources shouldbe coordinated. Such effort involves all levelsof government, other agencies and stake-holders in a structured and focused processsince a sustainable community is intercon-nected with surrounding communities andthe sustainability of a larger region is sup-ported by the collaboration of these commu-nities (Thomas and Furuseth, 1997). Proper
land-use planning within a watershed canprotect water quality and reach economicgoals. Although watersheds are increasinglyviewed as appropriate natural spatial unit forplanning and for sustainable water resourcesmanagement, watersheds have not receivedas much attention in land-use planning fieldas that in the biological and environmentalstudies. This may be attributed to the natureof traditional planning practice. Watershedsare often divided into areas that are underdifferent planning and political jurisdictionsand the coordination among them is oftenminimal. With more studies demonstratingthat the effects of human activities can anddo cross political boundaries the developmentand implementation of water-quality-basedwatershed land-use plans should be viewedas an integrated and holistic approach.
The LMR study demonstrates several evi-dences that call for integration of water-quality management and land-use planningto aim at water uses in a manner that willmaximize the socio-economic benefits to thesociety without jeopardizing the balance ofthe resource-related ecosystems. Althoughwater chemistry in the LMR watershed wasat good condition, biotic indicators havepicked up the effect of human activities onthe water quality. Such effect is a combina-tion of point and non-point sources, which areconnected with land uses in the watershed,and the riparian habitat quality. The rela-tionship between water quality of receivingrivers and land uses in a watershed indi-cates that increasing population pressure ina watershed is resulting in increasing loadsof nutrients and other pollutants which maycause severe degradation of water qualityand consequent use impairments of the waterbodies. The integration of water-quality man-agement and land-use planning can promoteprotecting the biotic quality and habitathealth and preventing pollution from happen-ing, which serves the purpose of protectingwater quality and maintaining ecologicallyand economically healthy land development.
The study also demonstrates that the riverbiological integrity is strongly related tothe habitat health (Tables 4 and 5). Thislinkage suggests that the goal of protectingwater quality through land-use planningcan and should be achieved through habitatprotection. Maintaining a healthy habitat canhelp to improve water quality and promote
Water-quality and land-use planning 35
biodiversity and preserve landscape featuresand the aesthetic appeal of the watershed.A good example of such integration is todevelop riverside corridors that can havemany benefits such as protecting waterquality, enhancing biological diversity andminimizing soil erosion.
As water quality and land-use data becomemore accessible, planners and policy-makersat different levels should bring stakeholderstogether to substantially increase the healthof the environment by identifying sources ofthe problems, understanding the relationshipbetween the sources and consequences, andsearching for solutions to these problems.This study shows that such effort can be at alocal level, such as protect and improve ripar-ian habitat through a variety of planningpractices such as vegetation buffers alongrivers and better management of dischargesinto the river. The protection of river alsoextends to land uses in the entire watershed,which requires a more regional collaboration.
Acknowledgements
The author thanks Scott Dyer and Charlotte Whitewho provided data and initiated the study, and theanonymous reviewers who contributed throughdiscussions and comments for this manuscript.
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