Hayden Lake Watershed Improvement District

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      • Idaho Water Quality Standards & Hayden Lake
      • The Eutrophication of Hayden Lake
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News from the 'Shed

the most important NEWS of the day in the HAYDEN LAKE WATERSHED

Stakeholder Engagement Thought Experiment

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Invasive Species Found in Hayden Lake

HLWID at the Wooden Boat Show

ISDA Staff conduct surveys on Hayden Lake

2024 Hayden Lake Invasive and Noxious Weed Updates

May ’24 – A Month of Meetings

  • HLWID, Invasive & Noxious Weeds
  • March 18, 2019
  • HLWID, Invasive & Noxious Weeds
  • March 18, 2019

Great Community Turn-Out for the Invasive Species Info Meet-N-Greet

Jeremey Varley presented at the 2019 Invasive Speecies meeting
Jeremey Varley from Idaho State Department of Agriculture shares 2019 Noxious Weed Treatment Plans for Hayden Lake

On Thursday, March 7, Jeremey Varley from Idaho State Department of Agriculture presented ISDA’s Noxious Aquatic Weeds’ Department’s plans for treating Curly Leaf Pond Weed in Hayden Lake.

Standing-room-only greeted late-comers to the meeting, signaling the significant level of interest on the community’s part. Attendees appreciated the early-release of the treatment plan information as well as the opportunity to ask questions and express concerns over weed management.

Varley reviewed last year’s treatment:

  • focused on Eurasian Watermilfoil
  • treated shallow areas of shoreline all around the lake
  • covered the entire North Arm of the lake

    Forrest Walker pulls up anchor, overloaded with Curly Leaf, in May '18.
    Forrest Walker pulls up anchor, overloaded with Curly Leaf, in May ’18.

ISDA follows the Idaho Noxious Weeds Rule when making decisions regarding what to treat and where. Curly Leaf Pond Weed is low on the priority list in that rule. But, in previous years’ treatments in the rich growing environment of the North Arm, Curly Leaf filled in behind the dying Milfoil before native vegetation could take hold. Further treatments, in 2019, for milfoil alone, would not address the whole problem. Therefore, ISDA has chosen a chemical treatment and timing that they expect to inhibit both Curly Leaf and Pond Weed. In Jeremey Varley’s words, “We want the native, natural environment to be able to recover on its own.”

What Chemical Will Be Used to Treat Weeds in Hayden Lake?

Planned are applications of a chemical herbicide whose active ingredient is Fluridone. It takes the form of a slow, time-release pellet. The contractor, Aqua Technex will apply it in concentrations well below Fluridone’s safety limit. The Fluridone targets Curly Leaf and will affect the emergence of Milfoil as well.  The history of this chemical treatment indicates that there will be Curly Leaf next year, but less of it. And, while slightly stunted this year, next year’s recuperation of the native species will be stronger.

Lake-water use is a concern that impacts treatment decisions. ISDA selected Fluridone because it imposes no potable-water restrictions as long as the application rate is below 20 parts per billion (ppb). The planned application is 12 ppb at most, well below the maximum. There are irrigation restrictions: peppers and tomatoes are susceptible to the chemical above 5ppb, and all seedlings are vulnerable as well. Established crops are safe. To address this, they are targeting treatments at a time in the growing season when there is less water needed for gardening. A FASTest at each of 3 sites, once per treatment, will ensure the water is safe to use for gardening.

When Will Chemical Treatment Take Place?

Treatments will take place starting early May and will be repeated every three weeks for a total of three treatments. This treatment strategy gives the contact time needed for the chemical to penetrate the Curly Leaf plant system, including its turions. Its effect extends to the milfoil that is coming up behind the Curly Leaf. The next treatment phase will specifically target Milfoil and will take place in July IF surveys indicate the need.

Where will the treatments take place this spring?

Treatment will take place only in the North Arm area because that’s where seen the Curly Leaf was growing. Fall surveys of Mokins Bay did not reveal Curly Leaf in that bay. Treatments will follow the contours of the drop-off or shelf that separates the North Arm and the main body of the lake.

How Does Curly Leaf Pond Weed Spread?

Curly Leaf spreads in much the same way as Milfoil. That is, pieces of weed that break off when the water is agitated become rooted in the sediment at the bottom of the lake and grow. The small and buoyant fragments easily float to other areas of the lake. The dense, longer strands catch in motors, ropes, anchors, etc. so that boats easily carry them from one part of the lake to another. The weed requires shallow, warm water to thrive, so the shallower bays and shorelines quickly fall victim to either easily-spread species.

Curly Leaf also propagates via turions which are small pinecone-like structures that float freely and plant themselves in the shallow lake-bottom. They are hearty and can lie dormant for great lengths of time, sprouting later under favorable conditions.

What Other Questions Need to be Addressed?

Think of this session with ISDA as the beginning of the conversation. Learn more about Curly Leaf Pondweed via ISDA’s informational handout. Track treatment plans on the Invasive Species of Idaho website. If you have other questions or concerns, you may contact Jeremey directly at
[email protected]. Please also share your questions here. We will find answers for you and publish them in future posts.

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HLWID at the Wooden Boat Show

ISDA Staff conduct surveys on Hayden Lake

2024 Hayden Lake Invasive and Noxious Weed Updates

May ’24 – A Month of Meetings

Stakeholder Engagement Thought Experiment

Communication Signup

Invasive Species Found in Hayden Lake

Stakeholder Engagement Thought Experiment

Communication Signup

Invasive Species Found in Hayden Lake

  • Related Content: HLWID, Invasive & Noxious Weeds
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About HLWID

The mission of the Hayden Lake Watershed Improvement District is to protect and enhance the water quality and the environmental quality within the watershed.

News from the 'Shed

Recent Posts
  • Hayden Creek Area Closed to Shooting Oct. 21-27 ’24
  • Cyanobacteria-HAB Advisory Continues – Watch Out!
  • Harmful Algal (Cyanobacteria) Bloom: July 27-?
  • 2024 Hayden Lake Aquatic Weed Update – Treatment – Restrictions Lifted
  • HLWID at the Wooden Boat Show

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Home

News From the 'Shed

Hayden Creek Area Closed to Shooting Oct. 21-27 ’24

Cyanobacteria-HAB Advisory Continues – Watch Out!

Harmful Algal (Cyanobacteria) Bloom: July 27-?

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Monday 4/16, 7:00 p.m.

HLWID Monthly Meeting

HLWID's Monthly Meetings will move to teleconferencing in order to ensure the health and safety of our constituents. For 4/16's meeting, dial 641-715-0861 and enter code 398963# at the prompt. This is a public meeting; all are welcome.