Nature of Activity: The Nation’s first point/nonpoint effluent trading program was implemented for the Dillon Reservoir. The reservoir serves as a source of drinking water for the Denver area and is also a recreational spot. The local communities believed that a growing population would threaten water quality in the Reservoir. A group of governmental and private stakeholders developed a phosphorus control program that included ambient water quality standards for phosphorus, phosphorus effluent load allocations for sources, and a provision for instituting trading program. Two trades have occurred and more than ten nonpoint source projects have generated credits that have been banked but not yet used or sold. The two completed trades involved terminating household use of septic systems and connecting them to sewers for treatment at POTWs. The banked credits have involved projects to collect, detain and filter surface and subsurface storm water, thereby reducing sediment and associated nutrient loads. The Frisco sanitation district POTW has been accumulating credits and is seeking a way to apply the credits to allow increased discharge by the Carver Mountain district POTW, but there is currently no provision for point/point trading. The program may grow more active if population growth or other water quality stressors increase.

Environmental Problem: General water quality and eutrophication.

Pollutant(s) / Pollution Type(s): Total phosphorus

Trade Types: Point sources may obtain offsets by controlling loads from nonpoint sources that existed prior to 1984.

Stage of Implementation: The State of Colorado established the phosphorus control regulation for the area in 1984. Trading has been allowed since 1984. The most recent trade was in 1996; the first trade was in the early 1990's.

Relation to TMDL: The water quality standard, point source allocations and trading provisions established for the program were the basis for a TMDL submitted in 1997.

Number of Potential Participants: There are four major POTWs, several minor WWTPs and various nonpoint sources in the area.

Trading Ratios: Point sources can trade with nonpoint sources at a ratio of 2:1.

Estimated Cost Savings: Unknown

Available Written Information: Brief reports are available from U.S. EPA Region 8 and from the Great Lakes Trading Network. The Summit Water Quality Committee has various reports and data available.

Innovative Aspects: The Dillon Reservoir program is the Nation's first point/nonpoint effluent trading program. The Summit Water Quality Committee has strict standards regarding what activities are eligible for trading.

Obstacles: Improved POTW operations have reduced phosphorus discharges significantly, resulting in minimal incentive to trade. Moreover, the Summit Water Quality Committee has been fairly strict in defining the reductions or operating improvements that may be eligible for trading. Participants are very reluctant to allow trading unless they believe that the improvement is truly "additional", i.e., it would not have occurred anyway, in the absence of the trading program.

Web Sites: Blue River: http://www.epa.gov/surf2/hucs/14010002/

Contacts: Bill McKee, Colorado Department of Public Health and Environment, (303) 692-3500, bill.mckee@state.co.us

Lane Wyatt, Summit Water Quality Committee, (970) 468-0295, qqlane@Coocolorado.net