Avista LAKE SPOKANE DISSOLVED OXYGEN WATER QUALITY ATTAINMENT PLAN
Click here for Avista Letter to FERC (Federal Energy Regulatory Commission) submitting proposed Lake Spokane Dissolved Oxygen Water Quality Attainment Plan.
Click here for Water Quality Attainment Plan submitted. This is a very large PDF document that may take significant time to download.
Below is the executive summary of the plan submitted.
EXECUTIVE SUMMARY
The Washington Department of Ecology (Ecology) has determined that the dissolved oxygen (DO) levelsin certain portions of the Spokane River and Lake Spokane do not meet Washington’s water quality standards. Consequently, those portions of the River and Lake are listed as impaired water bodies under Section 303d of the Clean Water Act. In response, Ecology developed the Spokane River and Lake Spokane Dissolved Oxygen Total Maximum Daily Load Water Quality Improvement Report (DO TMDL), issued on February 12, 2010.
Reduced DO levels are largely due to the discharge of nutrients into the Spokane River and Lake Spokane. Nutrients are discharged into the Spokane River and Lake Spokane by point sources, such as waste water treatment facilities and industrial facilities, and from non-point sources, such as tributaries, groundwater, and stormwater runoff, relating largely to land-use practices.
Avista Corporation (Avista) owns the Spokane River Hydroelectric Project (Project), which consists of five dams on the Spokane River, including Long Lake Hydroelectric Development (HED) which creates Lake Spokane. Avista does not discharge nutrients into either the Spokane River or Lake Spokane. However, the impoundment creating Lake Spokane increases the residence time for water flowing down the Spokane River, and thereby influences the ability of nutrients contained in those waters to reduce DO levels.
Avista received a new, 50-year license for the Project from the Federal Energy Regulatory Commission (FERC) on June 18, 2009 (FERC 2009). The license incorporates a water quality certification (Certification) issued by Ecology under Section 401 of the Clean Water Act (Ecology 2009). The Certification (included as Appendix A) requires Avista submit this Lake Spokane Dissolved Oxygen Water Quality Attainment Plan (DO WQAP).
As required, this DO WQAP addresses Avista’s proportional level of responsibility as determined in the DO TMDL. It identifies potentially reasonable and feasible measures to improve DO conditions in Lake Spokane, and incorporates an implementation schedule to analyze, evaluate and implement such measures. In addition, it contains benchmarks and reporting sufficient for Ecology to track Avista’s progress toward implementing the plan within the ten-year compliance period.
The DO TMDL defines Avista’s proportional responsibility for control measures by reference to Table 7 of that document (Appendix B). In Section 2.0 of this DO WQAP, Avista estimates that addressing Table 7 would require reductions within the range of 511 to 1,896 kilograms (kg) of phosphorous annually. Avista has identified a number of potentially reasonable and feasible measures associated with Lake Spokane that have the potential to yield such reductions. Briefly, those include: 1) reducing carp populations, 2) aquatic weed management, 3) acquiring, restoring, and/or enhancing wetlands, 4) Hangman Creek load reduction, 5) education regarding septic system maintenance and improvements, 6) lawn area reduction and native vegetation buffers, 7) grazing land conversion, 8) 8) maintaining a vegetative shoreline buffer on Avista owned property, and 9) modifying the intake of an agricultural irrigation system. These measures represent a significant load of nutrients that was not explicitly assigned as either a point source or non-point source load allocation in the DO TMDL.
Based on preliminary evaluations, Avista proposes to focus its initial efforts on two measures: reducing carp populations and aquatic weed management, which are expected to have the greatest potential for phosphorus reduction. Study plans to further evaluate these two measures are included in Appendices C and D.
When Avista implements such reasonable and feasible measures, fulfills Washington Administrative Code (WAC) 173-201A-510(5), and addresses the DO deficits referenced in the DO TMDL, it will have met the conditions of the Certification. The Certification states that in such an event, Ecology will consider changes to reduce reporting and monitoring requirements. If, on the other hand, the implementation of reasonable and feasible measures does not fully address Avista’s proportional responsibility within 10 years, and no new reasonable and feasible measures are identified, the Certification states that Avista may pursue one or more of the alternative means of compliance specified in WAC 173-201A-510(5)(g)(ii).