Summary results: draft PSU DO TMDL scenarios

June 23, 2009

Spokane Stakeholders,

Attached please find the draft PSU (Portland State University) report that summarizes the results of 4 different TMDL scenario runs for the Spokane River TMDL.

The technical specifications for each of the four scenario runs are outlined in Tables 1-4 (and are identical to the technical specifications that I sent out to you on June 15). For each scenario, the resultant impacts on DO levels in Lake Spokane are summarized in Tables 9-11. The in-stream phosphorus concentrations at the upstream end of Long Lake (2 locations) are illustrated in Figures 2 and 3. Please note that in Figure 3, the high total phosphorus concentrations of the TMDL alternatives are the result of algae biomass moving upstream in the reservoir due to surface currents.

We received the report late yesterday, and have just started discussing the report here at our office this morning. We look forward to talking with you about the report on Thursday.

Safe travels,

Laurie