Avista's Monroe Street hydroelectric project on the Spokane River in downtown Spokane is subject to excessive sediment accumulation which can plug the facility intakes causing maintenance problems and curtailing power production. Obtaining the necessary 404 and HPA permits to remove the sediment requires a detailed characterization of the accumulated sediments.

Role/Services: WSE conducted sediment surveys, field investigations, and GIS analyses to characterize the quantity and nature of the accumulated sediments at the HED. Larry worked with Avista staff to coordinate the data collection and was responsible for preparing study documentation for use in permitting the proposed sediment removal. Chris Frei led the field data collection program and reporting.

Outcome: Avista used the study results and report to address key HPA and 404 permit conditions, allowing dredging of the accumulated sediment in September 2011 to restoring hydraulic capacity at the facility.

Monroe Street Hydroelectric Development, Spokane