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Aquatic Weeds

Aquatic plants represent a healthy component of a lake’s ecosystem, providing food, habitat and spawning grounds for fish and wildlife, as well as contributing to shoreline protection and overall water quality.

However, the introduction of non-native invasive weeds can have negative effects on lakes and rivers. These plants often outcompete the native species and can degrade water quality, destroy habitat, and spoil or reduce recreation opportunities.

As part of the Spokane River Project License, we have developed the following three Aquatic Weed Management Programs: 

  • Lake Spokane and Nine Mile Reservoir Aquatic Weed Management Program
  • Coeur d’Alene Lake Aquatic Weed Management Plan for Non-Tribal Waters
  • Coeur d’Alene Reservation Aquatic Weed Management Plan

The primary elements of these programs include:

  • Educational programs to inform the public of the problems associated with invasive aquatic weeds and how to prevent their spread and introduction into our water bodies.
  • Monitor and map the distribution of invasive aquatic weeds within designated areas.
  • Develop management strategies to help control invasive aquatic weeds.

Avista and its partners are working together to control the following invasive weeds at public and community recreation sites as well as problematic areas on Lake Spokane and Nine Mile Reservoir: Flowering Rush, Eurasian Water Milfoil, Yellow Floating Heart, White Lily, and Curly-leaf Pondweed.

In Coeur d’Alene Lake and the lower St. Joe and St. Maries rivers, Avista and its partners are working to control Eurasian Water Milfoil and a hybrid species of milfoil, which are currently the only known invasive aquatic weed species present within the Coeur d’Alene Lake system.

Invasive aquatic plants (weeds) have negative effects on:

  • Recreational uses such as boating, fishing, and swimming. 
  • Fish and wildlife habitat due to the creation of non-native monocultures within water bodies and along the shorelines. 
  • Water quality, in which plant sloughing, leaf turnover, and decomposition of large amounts of plant material at the end of the growing season increase phosphorus and nitrogen in the water column.  Dense mats of aquatic weeds alter water quality by raising the pH, decreasing oxygen under the mats, and increasing temperature. 
  • Aesthetics by creating monocultures and replacing native vegetation, as well as forming mats of decaying plants along shorelines. 

Eurasian Water Milfoil
(Myriophyllum spicatum)

Eurasian Water Milfoil         

Curly-Leaf Pondweed (Potamogeton crispus)

Curly-Leaf Pondweed

 

White Lily (Nymphaea odorata

White Lily            

Yellow Floating Heart (Nymphoides peltata)

Yellow Floating Heart            
 

Flowering Rush (Butomus umbellatus)

Flowering Rush 
To help protect our local rivers and lakes from invasive species, here are some tips to remember as you take to the lake or river:

  • Remove all sediment and vegetation from boats, trailers, and fishing gear when traveling between different lakes or rivers. Don’t forget to clean your waders.
  • Wash and dry all boats, trailers, and fishing gear thoroughly between trips.
  • Disinfect gear (especially waders and live wells) if you have been in an area containing aquatic invasive species.
  • Stop at every boat check station in your area.

Remember, it is illegal to transport invasive species and it only takes one mistake to infest a new area.

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Aquatic Weed Work Plans and Reports

As part of the Spokane River Project License, we implement three Aquatic Weed Management Programs in consultation with various regulators, agency partners, and stakeholders. 

Work Plans and Reports associated with each of the three programs include the following:Aquatic Weeds

Lake Spokane and Nine Mile Reservoir Aquatic Weed Management Program 
Regulators, agency partners, and stakeholders – Washington Department of Ecology, Washington Department of Fish and Wildlife, Washington Department of Natural Resources, Washington State Parks, Stevens County Conservation District, Stevens County Noxious Weed Control Board, Spokane County Conservation District, Spokane County Noxious Weed Control Board, Lincoln County Weed Control Board, and the Lake Spokane Association.

2014 Lake Spokane and Nine Mile Reservoir Aquatic Weed Program Summary Report (dated February 25, 2015) 
2013 Aquatic Weed Summary Report (dated February 28, 2014)  
2012 Aquatic Weed Summary Report (dated February 28, 2013) 
2011 Aquatic Weed Summary Report (dated February 27, 2012) 
Coeur d’Alene Lake Aquatic Weed Management Plan for Non-Tribal Waters 
Regulators, agency partners, and stakeholders – Coeur d’Alene Tribe, Heyburn State Park, Idaho Department of Environmental Quality, Idaho Department of Fish and Game, Idaho State Department of Agriculture, Kootenai County Noxious Weed Control Board, and the U.S. Fish and Wildlife Service.

2014 Summary Report Coeur d’Alene Lake Aquatic Weed Management for Non-Tribal Waters (dated February 25, 2015) 
2013 Aquatic Weed Annual Summary Report (dated February 28, 2014) 
2012 Aquatic Weed Annual Summary Report (dated February 28, 2013) 
2011 Aquatic Weed Annual Summary Report (dated February 28, 2012) 
Coeur d’Alene Lake Reservation Aquatic Weed Management Plan 


Regulators, agency partners, and stakeholders – Coeur d’Alene Tribe and the U.S. Bureau of Indian Affairs.

Annual Work Plans and Summary Reports are not required. Information is available upon request by contacting Avista’s Terrestrial Resource Specialist. 

Avista holds annual meetings, typically in the winter and spring, to gather input and to provide information about implementing the three aquatic weed management programs. These meetings are essential in that they provide information exchanges that often lead to a more common understanding of the current invasive aquatic weed(s) of concern and how to effectively control these weeds in a cost-effective manner. Avista and its partners have also found that by sharing costs and information they can often accomplish more effective weed control programs with limited resources.

For more information about Avista’s Aquatic Weed Management Programs, please contact:

David Armes
Terrestrial Resource Specialist
Avista Utilities
1411 E. Mission Ave., MSC-1
Spokane, WA 99220-3727
Office: (509) 495-2796
david.armes@avistacorp.com 

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