Nature of Activity: The Idaho Department of Environmental Quality and the U.S. EPA are developing a watershed-wide trading program for the lower Boise River. Several important program design issues remain to be resolved.

Environmental Problem: Conditions for nuisance aquatic growth in the Boise River, and actual nuisance aquatic growth in the Snake River’s Brownlee Reservoir, to which the Boise is the largest source of phosphorus loadings.

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

Trade Types: Point/point and point/nonpoint.

Stage of Implementation: The project started in November 1997. A project design was presented to EPA for review in December,1999. The project developers expect to have a finalized framework by March, 2000. The project developers also expect that the not-for-profit organization that will administer the trading program will be incorporated and funded by the end of summer 2000. Some demonstration trades may take place before the TMDL is implemented. The goal is to implement trading within the TMDL for the Lower Boise – which was rescheduled for completion by the end of 2001 – so as to coincide with the Brownlee TMDL.

Relation to TMDL: The project is coordinating development of trading within the framework of a TMDL. Oregon also has a TMDL for the Brownlee Reservoir, due by 2005.

Number of Potential Participants: Seven POTWs, three industrial dischargers, and eight irrigation districts.

Trading Ratios: The program is considering three kinds of ratios or discounts: "delivery" ratios, "location" ratios and "uncertainty"discounts. All three are intended to relate the upstream (or up-drain) reduction to the actual downstream (or drain outfall) effect. Delivery ratios would be employed for reductions from agricultural sources discharging into a drain to reflect the fate and transport of phosphorus through the drain to the outfall to the river. Location ratios would be employed for NPDES permit holders and tributaries/drains, in order to relate the reduction at the point of discharge to the actual effect at Parma (the mouth of the Boise River). An uncertainty discount would be applied to credits generated by a nonpoint source practice for which monitoring or actual measurements are impractical or infeasible, to account for variability in the effectiveness of the practice.

Estimated Cost Savings: Municipalities were asked to consider what their 20-year plan would be in the face of a mandated 20%, 40% or 80% phosphorus reduction, given a low population growth scenario and a high population growth scenario. The municipalities responded that the cost range for an 80% reduction would be $12 -$178/lb. of phosphorus. For nonpoint sources, the stakeholders determined that the costs of phosphorus BMPs would be in the range of $2 - $20/lb. of phosphorus. The implied expected cost savings are therefore $10 - $158/lb. of phosphorus reduced.

Available Written Information: A brief description of the project is available on EPA Region 10's web site.

Innovative Aspects: Three types of trading ratios are being discussed. The program might form a not-for-profit association to record the trades rather than the State or EPA. The system is being designed with adequate safeguards to support frequent, "on demand" trades without requiring case-by-case agency review.

Obstacles: Project development has been expensive and resource-intensive. Water rights are an issue for the irrigation districts and the farmers. Nonpoint sources are wary that their participation in generating credits by reducing loads may encourage their being subjected to regulations requiring load reductions. Whether trading can occur against interim targets within a phased TMDL is a legal issue under investigation.

Web Sites: Lower Boise: http://www.epa.gov/surf2/hucs/17050114/

Contacts: Claire Schary, EPA Region 10. (206) 553-8514, schary.claire@epamail.epa.gov

Larry Peterson, Idaho DEQ. (208) 373-0252, or lpeterso@deq.state.id.us