2010

1. A Watershed Approach: Developing a TMDL to Meet Water Quality Standards 2010 Barr Lake & Milton Reservoir Watershed Association

2. Outline • The Reservoirs • Regulatory Issues – Impairment Listings • Watershed • The Association and its Process • TMDL Specifics

3. Barr Lake • 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

4. Milton Reservoir • 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

5. Regulatory Drivers • 2002 State 303(d) listing for pH impairment (both Barr and Milton) – exceedences above 9.0 pH units • 2010 listings for ammonia, D.O. A TMDLis a calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources. Total Allowable Load

6. Symptoms Problem Poor Clarity High pH Low Oxygen Excessive Nutrients (Phosphorus Nitrogen) Algae Blooms Taste/Odor Aesthetics Fish Kills Nutrient Problem Cultural Eutrophication Barr and Milton are classified as hypereutrophic

7. Nutrient Sources • Municipal wastewater point sources • Municipal stormwater point sources • Urban non-permitted stormwater • Agricultural nonpoint sources • In-reservoir recycled nutrients from sediments

8. Milton Res. Big Dry Creek Barr Lake 1st, 2nd, & 3rd Creek Standley Res. Clear Creek Sand Creek S. Platte River Cherry Creek Bear Cr. Res. Bear Creek Marston Lake Cherry Cr. Res. Chatfield Res. Creeks, Streams, and Reservoirs Aurora Res.

9. BMW Watershed (datashed) • 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

10. 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 AssociationHistory

11. 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 Wastewater Mgmt Agencies Cities/Counties Drinking Water Providers Regulatory and Planning Agencies Recreation Interests Raw Water Providers

12. Mission/Vision Mission to encouragecooperation, involvement, and awareness by all interested parties incollaborativeefforts toimprove the water qualityof Barr Lake and Milton Reservoir. Vision tomaintain appropriate water qualityin Barr Lake and Milton Reservoir through thecontinuousimplementation of a collaboratively-developedwatershed management plan. Clearcommunicationto all watershed stakeholders will be a major attribute.

13. Association Funding • 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)

14. Association Decision Making • 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

15. 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 Modeling(Facts) Barr Lake

16. Modeling(Uncertainty) ? Uncertainty What is background pH? Will chl-a drop if TP is reduced? What TP level will drop pH below 9.0?

17. 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 Modeling(conclusions)

18. 3rd PartyPhased TMDL 3rd Party = Someone besides the State writes the TMDL. The BMW Association is the third party. 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. pH TMDL = Allocations = All permitted point sources will be assigned phosphorus allocations under the wasteload term. Because of uncertainty with how pH will change with phosphorus reductions, the TMDL will be updated in the future with new information. Phased =

19. 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.

20. 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 Adaptive Implementation Plan

21. $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ Potential Solutions Potential Strategies to Examine • 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

22. $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ Potential Solutions Potential Strategies to Examine • 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.)

23. Timeline to 2020 TMDL Long-Term Schedule Limnocorral Studies Additional WQ Regulations (e.g., Temp Mod., UAA, & Nut. Stds.) Point Source Reductions & Treat Internal Loading 2010 2012 2014 2016 2018 2020 Approve TMDL & Implementation Plan Special Studies Revisit pH TMDL

24. Visitwww.barr-milton.org Contact our coordinator Amy Conklin at amy.conklin@comcast.net More Information