The Changing Spokane River Watershed: Actions to Improve and Maintain Water Quality

Abstract

Maintenance of water quality today requires legislative control as well as scientific information. Economic or other considerations can no longer be used to justify the degradation of aquatic systems by wastewater disposal. The Spokane River, along with its various tributaries, is presented as an example of water resource planning and management resulting in improved water quality. The Spokane River and its major reservoir, Long Lake, have had numerous water quality problems and associated controversies. Long Lake has experienced massive algal blooms and ever-expanding stands of macrophytes. The main source of nutrients (particularly phosphorus) was the city of Spokane’s primary sewage treatment facility. Advanced wastewater treatment initiated by Spokane in 1977 markedly improved the trophic condition of the reservoir. A phosphorus waste-load allocation for all point and nonpoint source dischargers in the drainage (Washington and Idaho, USA) was initiated in the early 1980s to protect and sustain the improved water quality of Long Lake. The Washington State Department of Ecology later established a legally enforceable standard such that the total maximum daily phosphorus load to the reservoir was to be no higher than 259 kg to effect mid-mesotrophic conditions. Recently, regulators, dischargers, and scientists have joined forces in the management of phosphorus loads in the Spokane River drainage basin. These managers are demonstrating that the most effective way to ensure good water quality is through local control of degradation processes.