2010

Barr Lake & Milton Reservoir Watershed Association

A Watershed Approach:

Developing a TMDL to Meet Water Quality Standards

• The Reservoirs

• Regulatory Issues – Impairment Listings

• Watershed

• The Association and its Process

• TMDL Specifics

Outline

• Owned by FRICO (Farmer’s Reservoir and Irrigation Company)• Historic Uses - Agricultural Irrigation, Recreation, Aquatic Life Habitat• New Uses – Drinking Water (2004) • State Park management • Filled during the winter and early spring• Releases during irrigation season (May – September)• Source water S. Platte at Burlington headgate (94%) • 30,071 AF volume• 1,833 surface acres• 34 feet max. depth• 225 day residence time

Barr Lake

• Owned by FRICO • Historic Uses - Agricultural Irrigation, Recreation, Aquatic Life Habitat• New Uses – Drinking Water (2004) • Filled winter/early spring, releases during irrigation season • Source water S. Platte at Platte Valley headgate (54%) and Beebe

Canal (37%)• 24,029 AF volume• 2,082 surface acres• 26 feet max. depth• 192 day residence time

Milton Reservoir

• 2002 State 303(d) listing for pH impairment (both Barr and Milton) – exceedences above 9.0 pH units

• 2010 listings for ammonia, D.O.

Regulatory Drivers

A TMDL is a calculation of the maximum amount of a pollutant that a water bodycan receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources.

Nonpoint/BackgroundLoads

Margin ofSafety

PointSourceLoads

Total Allowable Load

Symptoms

ExcessiveNutrients

(PhosphorusNitrogen)

Algae Blooms

Low Oxygen High pH

Fish Kills

PoorClarity

Taste/Odor Aesthetics

Problem

Cultural Eutrophication

Nutrient Problem

Barr and Milton are classified as hypereutrophic

• Municipal wastewater point sources

• Municipal stormwater point sources

• Urban non-permitted stormwater

• Agricultural nonpoint sources

• In-reservoir recycled nutrients from sediments

Nutrient Sources

Barr LakeBarr Lake

Milton Res.Milton Res.

Cherry Cr. Res.Cherry Cr. Res.

Bear Cr. Res.Bear Cr. Res.

Standley Res.Standley Res.

Chatfield Res.Chatfield Res.

Marston LakeMarston Lake

Creeks, Streams, and Reservoirs

S. Platte RiverS. Platte River

Bear CreekBear Creek

Cherry CreekCherry Creek

Clear CreekClear Creek

Big Dry CreekBig Dry Creek

Sand CreekSand Creek

11stst, 2, 2ndnd, & 3rd Creek, & 3rd Creek

Aurora Res.Aurora Res.

BMW

• Population: 2.5 Million (1 in 2 Coloradoans)

• 850 Sq. Miles Including 6 Front Range Counties

• 90% Privately Owned

• 35% Residential, Industrial, and Commercial

• 49% Agricultural

• 500 Miles of Streams and 550 Miles of Canals

Watershed (datashed)

AssociationHistory

• 2000 - S.P. Triennial Hearing – WQCC directed Division to assist in formation of a Barr/Milton stakeholder process

• 2002 – Initial series of outreach meetings organized by Division

• 2002 – Phase I 319 grant to fund organizational development, facilitation, and development of initial database

• 2005 – Incorporated BMW Association as 501(c)6• 2005 – Phase II 319 grant to fund technical studies

and development of watershed plan and TMDL

AssociationBoard

• City of Aurora

• City & County of Denver

• City of Thornton

• Denver Water

• East Cherry Creek Valley Water & Sanitation

• S. Adams County Water & Sanitation District

• United Water & Sanitation District

• Littleton/Englewood Wastewater Treatment Plant

• Metro Wastewater Reclamation District

• S. Platte Coalition for Urban River Evaluation

• Farmers Reservoir and Irrigation Company

• Barr Lake State Park

• Steven Janssen

Cities/Counties

Drinking Water Providers

Wastewater Mgmt Agencies

Recreation Interests

Raw Water Providers

Regulatory and Planning Agencies

Missionto encourage cooperation, involvement, and awareness by all interested parties in collaborative efforts to improve the water quality of Barr Lake and Milton Reservoir.

Visionto maintain appropriate water quality in Barr Lake and Milton Reservoir through the continuous implementation of a collaboratively-developed watershed management plan. Clear communication to all watershed stakeholders will be a major attribute.

Mission/Vision

• Section 319 grant funding from CDPHE• 90/10 match over 6-year period• Grant funds = $301,900• Association Match = $2,724,100• Match source provided by Association members in form of

dues, water quality monitoring costs, technical support• Final deliverable pH TMDL (2010)

Association Funding

• Substantive decisions make by stakeholders• Consensus based approach requiring minimum 90%

agreement on issue• Procedure for roll call vote when consensus cannot be

reached• Board composition determined by membership level with at-

large component• Board oversees all administrative functions • Board of Directors has veto authority

Association Decision Making

Modeling(Facts)

• Phosphorus is the critical nutrient to control

• Phosphorus load to Barr is ~ 70,000 kg/yr

• Phosphorus load to Milton is ~ 40,000 kg/yr

• Phosphorus loads to Barr and Milton need to be ~ 4,000 kg/yr/reservoir

• Chl-a explains about 54% of the variation in pH

• No linkage between Phosphorus and pH

90%

4%

6%Point Sources

Background Loads

Internal Load

Barr Lake

Milton Reservoir Summer Avg pH vs. TP mg/L

7.00

7.50

8.00

8.50

9.00

9.50

10.00

0.00 0.20 0.40 0.60 0.80 1.00TP (mg/L)

pH

(S

U)

Barr Lake Summer Avg pH vs. TP mg/L

7

7.5

8

8.5

9

9.5

10

0 0.2 0.4 0.6 0.8 1TP (mg/L)

pH

(S

U)

?Uncertainty

What is background pH?Will chl-a drop if TP is reduced?

What TP level will drop pH below 9.0?

Modeling(Uncertainty)

Modeling(conclusions)

• Best estimate: In-reservoir Phosphorus needs to be 100 ug/L to keep chl-a below 25 ug/L and pH below 9.0

• It will take a >95% reduction in both external and internal loading to see major water quality improvements

• Wastewater Treatment Plants will have to treat for Phosphorus

• Internal Phosphorus loading will have to be treated

• Any source to which more than about 0.6% of the total load can be attributed will require some attention, as the load reduction necessary to guarantee compliance is so extreme

3rd PartyPhased TMDL

Someone besides the State writes the TMDL. The BMW Association is the third party.3rd Party =

Phased =Because of uncertainty with how pH will change with phosphorus reductions, the TMDL will be updated in the future with new information.

pH TMDL =

A Total Maximum Daily Load (i.e., allowable load) to achieve the pH standard of 9.0 85% of the time. Phosphorus will be the surrogate parameter to achieve the pH standard since pH cannot be allocated to the sources.

Allocations = All permitted point sources will be assigned phosphorus allocations under the wasteload term.

Phased TMDL

A phased TMDL must include all elements of a standard TMDL.

•Allowable load takes into consideration the high level of uncertainty caused by predictive tools that may not adequately characterize the problem.

• Due to uncertainty, the TMDL allowable load and allocation plan can be revised in the future as additional information is collected.

• An adaptive implementation plan is required by EPA.

Adaptive Implementation

Plan

• Submitted with the phased pH TMDL

• Provides roadmap for implementation of phosphorus controls to reach targets defined in the TMDL

• Includes a schedule for installation and evaluation of source control measures, data collection, and assessment of water quality standards attainment

• Details technical studies to reduce/resolve uncertainty, the study schedule, and milestones for when TMDL loads/allocations will be revisited

Potential Solutions

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• Point Source

• Construction/operation phosphorus treatment facilities at wastewater plants

• Permitted Stormwater Management

• Re-examination of current controls, their effectiveness, ability to retrofit, and more stringent permit requirements

• Nonpoint Source

• Evaluation of contribution, current practices and their effectiveness, ability to implement additional BMPs

Potential Strategies to Examine

Potential Solutions

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• Regional Treatment Opportunities

• Construction of regional treatment systems (wetland, stormwater, alum)

• In-reservoir modifications to mitigate the effects of nutrient loading

• Water management techniques to offset loading effects

• Other

• Watershed-wide growth and development

• Regulatory options for implementation (phased TMDL, control regulation, etc.)

Potential Strategies to Examine

Timeline to 2020

2010 2012 2014 2016 2018 2020

Approve TMDL & Implementation

Plan

Limnocorral Studies

Point Source Reductions & Treat Internal Loading

Special Studies Revisit pH TMDL

Additional WQ Regulations

(e.g., Temp Mod., UAA, & Nut. Stds.)

TMDL Long-Term Schedule

More Information

• Visit www.barr-milton.org

• Contact our coordinator Amy Conklin at amy.conklin@comcast.net