2026 Aquatic Invasive Plant Treatments Planned for Hayden Lake
The Idaho State Department of Agriculture (ISDA) is continuing its efforts to control Eurasian watermilfoil in Hayden Lake with a combination of diver removal and targeted aquatic herbicide treatments. A hired applicator will be applying ProcellaCOR®, an aquatic herbicide, to specific treatment areas in Hayden Lake targeting current growth of Eurasian watermilfoil.
The 2026 treatment plan for Hayden Lake includes one diver-removal area and 11 chemical treatment areas. The current ISDA treatment map and Water Right Notification project treatment dates are occurring between August 25 – 28th, 2026. Weather, wind, and water movement can affect when an application takes place, so residents should check on ISDA’s treatment map frequently.
Critical: For the most up-to-date and correct information, review the Water Rights Notice and Dockside Notice
Where to find the latest treatment information
Treatment notifications are issued to the address-on-file for the water right associated with your property. According to ISDA, water-rights notifications and 24-hour dockside notices are the official means of providing information to affected property owners. Treatment dates and areas can change.
ISDA Aquatic Noxious Weed Treatment Map
Restrictions associated with ProcellaCOR®
- There are no drinking water restrictions.
- There are no restrictions for recreation or fishing.
- There are no restrictions for irrigation of turf grass.
- Irrigation restrictions for food crops and ornamentals: will start the day of application and will remain in place until post-treatment residue samples show a level of less than two (2) parts per billion (ppb). These samples will be collected by ISDA approximately 3 days after application and be evaluated by a contracted laboratory. Results, when available, will be immediately published to the ISDA treatment map.
What is being treated?
The target species is Eurasian watermilfoil, an invasive aquatic plant that can form dense underwater growth and outcompete native vegetation. ISDA identifies Eurasian watermilfoil as one of the most problematic invasive aquatic plants in North America because heavy infestations can interfere with boating and fishing and degrade aquatic habitats.
ISDA’s statewide aquatic invasive species program uses targeted management strategies to protect water quality, recreational uses and aquatic ecosystems.
The 2026 Hayden Lake plan uses two approaches:
- Diver removal: One designated area will be treated through physical removal by divers.
- Chemical treatment: Eleven designated areas will receive targeted treatment with ProcellaCOR®
ISDA uses both mechanical removal and herbicide applications as part of its aquatic invasive weed management program. In 2025, CleanLakes, Inc., conducted prescribed ProcellaCOR® treatments targeting Eurasian watermilfoil on several Idaho waterbodies and will again be responsible for applying the herbicide treatments on Hayden Lake.
Why your water-rights information matters
One of the most important things Hayden Lake property owners can do is make sure their contact information with the Idaho Department of Water Resources (IDWR) is current.
This is especially important if you are new to your property or have recently changed your mailing address.
If your information is out of date, you could miss an important notification about an upcoming treatment. If you own property on Hayden Lake, now is a good time to make sure your water-rights contact information is up to date. That information helps ensure you receive official notifications when aquatic invasive plant treatments are planned in your area.
Have you recently moved or purchased your property?
Depending on your situation, you may need to update your information with IDWR:
Taking a few minutes to make sure your information is current can help ensure you receive future treatment notifications.