Avista Operates under two Federal Energy Regulatory Commission (FERC) Licenses: Spokane River License Clark Fork License
Spokane River License Lake Spokane Aquatic Weed Management Program Coeur d’Alene Lake Aquatic Weed Management Plan for Non-tribal Waters Coeur d’Alene Reservation Aquatic Weed Management Plan
Goals for the Lake Spokane Aquatic Weed Management Program Include: Reduce cover of invasive aquatic weeds at public and community boat access points; Maintain a moderate level of ongoing control of aquatic weeds in areas of 10-14 feet using winter reservoir draw downs; and Support weed control and facilitate coordination among the entities involved in aquatic weed control.
Primary Elements of the Lake Spokane and Nine Mile Reservoir Aquatic Weed Management Program Education - Establish or expand educational programs to keep the public informed of the hazards of invasive aquatic weeds. Monitoring – Monitor and/or map the distribution of invasive aquatic weeds within the Project area. Management – Develop strategies to help control invasive aquatic weeds within the Project area.
Lake Spokane Invasive Aquatic Weeds: Eurasian watermilfoil (Myriophyllum spicatum)
Flowering Rush (Butomus umbellatus) Photograph of Flathead Lake, MT below
Approximate area of invasive aquatic weeds on Lake Spokane range from 634 acres (Tetra Tech, 2001) to 715 acres (AquaTechnex, 2007) survey.
In 2011 Avista Completed: Coordination with agencies, weed management entities and public and community boat launch managers to refine the 2011 Program Task List. Herbicide treatment of 15 acres at seven public and community recreations sites, with an 85% effectiveness. Flowering Rush control (hand removal) of approximately 200 plants at 28 locations. A Monitoring Report outlining the methodology of the pre- and post- treatment effectiveness monitoring. Educational items, including the development of a draft aquatic weed brochure specific to Lake Spokane and Nine Mile Reservoir.
2011 Treatment Sites for the Lake Spokane and Nine Mile Aquatic Weed Management Program
2012 Aquatic Weed Management Tasks A weed control reservoir drawdown of 13-14 feet during January and February. Finalizing and distributing the Lake Spokane and Nine Mile Reservoir aquatic weed brochure. Herbicide treatment of up to 15 acres focused on public and community boat launches. Continued flowering rush control. Aerial surveys/mapping of Lake Spokane and Nine Mile Reservoir for invasive aquatic weeds.
Coeur d’Alene Lake Aquatic Weed Management Plan for Non-tribal Waters Purpose and Objectives Expansion of aquatic noxious weed education programs Annual monitoring of aquatic noxious weed distribution Management of aquatic noxious weeds through identified control strategies
Milfoil distribution in Coeur d’Alene Lake is estimated between 1000-2000 acres
Coeur d’Alene Lake Aquatic Weed Management Actions Completed in 2010 Avista and the Coeur d’Alene Tribe treated 538 acres of milfoil with 2,4-D DMA 4 IVM and achieved 89% efficacy. Diver suction removal along the inner banks of the St. Joe and St. Maries rivers. Approximately 594 cubic feet of milfoil was removed from an estimated 5.7 acres spread along three river miles. Annual mapping was completed in Hidden Lake, Benewah Lake, the St. Joe River and along the western shoreline of Coeur d’Alene Lake.
Coeur d’Alene Lake Aquatic Weed Management Actions Completed in 2011 A dye study was completed in an effort to refine the understanding of wind-induced water movement. Herbicide treatment trials were completed in 14 one-half acre trial enclosures to evaluate two herbicides, DMA 4 IVM (a liquid formulation of 2,4-D) and Navigate (a granular formulation of 2,4-D). Diver suction removal of milfoil along the St. Joe and St. Maries Rivers. Approximately 14 acres of milfoil were treated.
Coeur d’Alene Lake Aquatic Weed Management Actions Completed in 2011 (continued) Bottom barriers (218 10’x10’ panels) were placed over one- half acre of milfoil along the western shoreline of CdA Lake. An aerial survey of milfoil habitat was completed for CdA Lake; diver surveys (IDEQ) were completed in six bays. Milfoil was identified in several new locations. An education brochure was completed discussing milfoil in CdA Lake.
Coeur d’Alene Lake Aquatic Weed Management Actions Proposed for 2012 Herbicide treatment (Navigate) of up to 538 acres of milfoil in CdA Lake. Barriers will be utilized in order to maximize the effectiveness of the treatments. Diver suction removal of milfoil in the St. Joe and St. Maries Rivers. Placement of up to one-half acre of bottom barriers. Aerial surveys and mapping of milfoil in CdA Lake; diver surveys (IDEQ) in six bays. Educational opportunities include participating in the North Idaho Fair, distributing milfoil brochures and coordinating with landowners.
Noxon Rapids and Cabinet Gorge, Clark Fork License Avista partners with the Eurasian Watermilfoil Task Force, which consists of over ten public and private entities. In 2009 Avista installed 40,000 square feet of bottom barriers. In 2009 (40 acres) and 2010 (80 acres) Avista completed dye/herbicide trials. In 2010 Avista funded educational opportunities and boat check stations. In 2012 Avista will continue to work with the Eurasian Watermilfoil Task Force on milfoil management.