Invasive Weeds

One of the issues that many of us face on Hayden Lake is the management of noxious weeds. The Association has been working with the local jurisdictions on an action plan to help combat these invasive species.

2014 Invasive Species Update

Here’s a link to the current status of the invasive species control efforts.

On January 16th, 2014 Tom Woolf, Aquatic Program Manager for the Idaho Department of Lands came to the HLWA board meeting and gave a presentation on the 2013 invasive species control efforts and an outlook on what to expect in 2014. It’s a mix of good news and bad news with high efficacy rates from the 2013 milfoil treatment, but the discovery of a treatment-resistant hybrid milfoil in certain areas of the lake. Check out the whole presentation here:

2014 Hayden Lake Invasive Species Update


Weed Mats

One of the methods of controlling noxious weeds in lakes is to use mats which suffocate out all weed growth. These mats have been used with great success on Lake Pend O’reille and have recently been approved for use on Hayden Lake. Each property owner may construct and have professionally installed up to 5 mats of approximately 8′ x 8′ dimension. Mats must be moved every 3-4 weeks and removed at the end of the season.

The 2012 application for weed mats may be found here:

Please complete as much of the application as you can and then call the Lake Manager Todd Walker at 208-771-0525 for assistance in filing and tracking the permit.

2013 Milfoil Update

June 20, 2013

Milfoil eradication treatments have just been performed by the State’s contractor on Hayden Lake and water use restrictions are now in effect. A map of the treated areas, as well as more details on the water use restrictions, can be found here:

Last year’s treatments were very effective and we hope that this year’s will produce similar results!

March, 2013

Tom Woolfe came to the February HLWA meeting with a presentation on the results of the 2012 invasive aquatics treatment as well as some details for the proposed 2013 treatments. In summary, the 2012 treatments were very successful over 72 acres and plans are being laid to treat over 100 acres in 2013. The herbicide used will be changed from Triclopyr to  2,4-D this year to increase effectiveness and reduce water restriction times. The full presentation can be found here:

2012 Milfoil Update

UPDATE 8/16/12: Tom Woolfe of the IDL gave a great presentation on the progress against milfoil and other invasive species at the HLWA annual meeting. You may view it here:

UPDATE 7/11/12: Milfoil eradication is still scheduled for July 16th, 2012. The official application notice can be found here:

Herbicide application will take place at night this year and will be performed by Clean Lakes, Inc.

The target date for application is July 16th, and notices will be sent out the week prior to application.

If individual lakefront homeowners are interested in additional weed control methods please contact Doug Freeland of Ace Diving. Doug can help homeowners obtain permits as well as perform the application and periodic relocation of the weed control mats. or 208-755-0800

A statement of qualifications for Ace Diving can be found here

To view or download the HLWA Weed Management Assistance Plan click here

Tom Woolf of The Idaho State Department of Agriculture is now managing the aquatic invasive species control work in Hayden Lake. Their website is here:

Tom gave a presentation to the Board in the spring of 2012 on their progress and future plans for aquatic invasive species in Hayden Lake.

Click Here for the Hayden Lake Update.


Invasive Weeds — 10 Comments

  1. 2011 Eurasian Milfoil updates

    Herbicide treatment 2011 update

    The unusual cool, wet, and high water spring experienced this year, delayed the growth of most aquatic weeds including the invasive Eurasian milfoil. Since treatment of the milfoil with herbicide depends on plants of some size, milfoil treatment was delayed until well into the summer. As events worked out, the weather warmed as did activity on the lake just as milfoil treatment by the county was to begin. The treatment was to start last Monday,

    July 25th, but windy weather and contractor obligations on the subsequent two days, postponed the start until Thursday, July 28th. Treatment was again curtailed on Friday due to the heavy motor boat use on the lake that essentially stirs the lake, diluting the herbicide and limiting its effectiveness. Treatment was finished on Monday, August 1st. The treatment has been an inconvenience, especially for those drawing potable and irrigation water from the lake in the vicinity of the posted treatment areas, but it is necessary to combat an aquatic weed species that can damage the lake’s ecology. Water samples will be taken on Monday August 8th to assess breakdown of the herbicide. The laboratory analysis has a same day turnaround time, so Kootenai County Noxious Weed Department should have the results by 4:30 to 5 PM that afternoon. You can check the results by calling the weed department at 208-446-1290 or visiting its website

  2. 2012 Eurasian Milfoil herbicide update

    This year a new herbicide product will be applied at night to prevent the wind from blowing it and reducing its effectiveness. The contractor this year will be Clean Lakes, Inc ( and the target date for application is July 16th, 2012. Notices to lakefront property owners will be sent out and placed next week.

  3. Here is the legal notice for the herbicide application in Hayden Lake.

    An aquatic herbicide application to treat the aquatic noxious weed Eurasian watermilfoil is planned for Hayden Lake (Kootenai County, Idaho) between the dates of July 16th and July 20th, 2012 and Cocolalla Lake (Bonner County, Idaho) between August 6th and August 10th, 2012. The aquatic herbicide Renovate (Liquid triclopyr, EPA Registration # 62719-37-67690) will be applied to up to 80 acres in areas of Hayden Lake and up to 70 acres in Cocolalla Lake, to control Eurasian watermilfoil. Irrigation restrictions will be in effect in the area until Triclopyr residue levels in the water are within levels specified by the herbicide label. Home owners who use water from the lake for drinking or irrigation are advised to not use lake water until herbicide residue samples indicate it is acceptable to do so. For up-to-date information about residue samples and the treatment visit the applicator’s website: Contact Tom Woolf, Idaho State Department of Agriculture, Aquatic Plant Program Manager, with any questions: 208-608-3404 or email at

  4. I recently moved to Hayden Lake from Alaska and am spending my first summer here. I am learning that the spraying for noxious weeds is a recurring annual program to help protect the waters and keep the lake viable for all users. What is missing is a targeted program to collect the vast amount of weeds that come to the surface, particularly after spraying. This year the problem is significant, as the floating debris is widespread and is accumulating in the northern bays due to the prevailing southerly winds. The weeds are are a navigation hazard for boaters and a nuisance for fishing. Along the shoreline, debris is mixed with dead fish, creating a stagnant mass that is most certainly a health hazard too. At a minimum, the viability of the lake is being negatively impacted.

    Funding should be pursued to “harvest” the debris that rises to the surface in addition to the current spraying program. I believe the HLWA Board is a suitable forum to take on such an endeavor with the State. Thank you for your consideration.

    Gregory Jones
    Hayden Lake resident

    • Gregory – Thanks for your comment, this is an issue that we’ve discussed as an organization. We’ll take your comments into consideration as we work with the newly formed Hayden Lake Watershed Improvement District to evaluate projects to maintain the lake. We would welcome you to attend the annual meeting on July 29th at 6pm the Hayden Lake Country Club to discuss your concerns.

  5. This years (2014) herbacide application worked far better this year than previous years. In years past the milfoil just came back 6-8 weeks later with a vengence. This year the milfoil only came back in much smaller areas which made me wonder if they could poison twice during the season and have a better chance of killing them for good?

  6. Steven – The current plans from the Idaho Department of Lands are for a herbicide treatment after Labor Day Weekend this year. They are still developing their strategy on how to treat the new hybrid milfoil that has developed in the lake. You can find more information and a link to the presentation provided by Tom Woolf of the IDL in the 2015 Annual Meeting Minutes posted on the website.

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