Nature of Activity: Phosphorus standards were established for the Chatfield Reservoir in order to protect the quality and recreational value of the water. A State control regulation (Colorado’s instrument to implement a TMDL) was established in 1993 that allows trading, although none has yet occurred. A 1996 study of phosphorus control options in the basin revealed that trading would only be cost-effective after POTWs institute fairly high levels of in-plant treatment. Significant population growth in the basin has created pressure for expansion of treatment facilities. Achievement of phosphorus limits in the face of this growth will likely require further controls, providing an impetus for a possible trading program. The dischargers in the area have signed a memorandum of understanding and have formed an association under Section 208 of the Clean Water Act to protect water quality in the reservoir. For trading to be instituted, specific guidelines must be added to the control regulation specifying the details of the program.

Environmental Problem: Eutrophication.

Pollutant(s) / Pollution Type(s): Phosphorus.

Trade Types: Point/nonpoint trading was examined in the study and authorized by the control regulation.

Stage of Implementation: The control regulation was first enacted in the early 1980s. The regulation was updated and included a clause allowing trading, but without much guidance regarding the specifics of the program. Revisions to the regulation that provide for the development of trading guidelines were approved in July ‘99.

Relation to TMDL: A TMDL has been in place since the 1980's and is updated every three years. The control regulation is the instrument to implement the TMDL.

Number of Potential Participants: There are six POTWs, one industrial discharger and various nonpoint sources in the basin.

Trading Ratios: N/A

Estimated Cost Savings: N/A

Available Written Information: A brief report is available from EPA Region 9. The results of the study were published in the proceedings of Watershed '96.

Innovative Aspects: Unknown

Obstacles: The study concluded that nonpoint source improvements and point/nonpoint trading are not necessarily the most cost-effective means to reduce pollution. In the Chatfield Basin, the study determined that a high level of point source control is necessary before nonpoint source controls are justified.

Web Sites: Upper South Platte: http://www.epa.gov/surf2/hucs/10190002/

Contact: Dick Parachini, Colorado Department of Public Health and Environment, (303) 692-3500, dick.parachini@state.co.us