Dear Lake Arrowhead shorefront owners:

A contractor for the Maine Department of Environmental Protection (DEP) will apply herbicide in portions of Lake Arrowhead this Thursday, July 20, 2023 to control the invasive aquatic plant brittle naiad (scientific name Najas minor).  I am writing because your property is within or near the treatment area.  DEP will post notification at boat access sites and beaches near the treatment area.

The treatment objectives are 1) to reduce spread of brittle naiad within Arrowhead and to other waters and 2) enable future control of this infestation with non-chemical means.  The treatment is timed to kill the brittle naiad before it forms seeds.

The herbicide Aquastrike will be applied because of its effectiveness on brittle naiad.  The following water use restrictions on the Aquastrike label apply to the treatment areas (product label found here

  • Do not drink lake water for 3 days after treatment
  • Do not allow livestock to consume lake water for 1 day after treatment
  • Do not irrigate turf and landscape ornamentals for 3 days after treatment
  • Do not irrigate food crops for 5 days after treatment


There is no swimming restriction for Aquastrike but the DEP advises residents not to swim within treated areas on the day of treatment as an added safety measure. The herbicide will be applied via subsurface injection through perforated hoses from an airboat.  The contractor will arrive early on Thursday and the treatment will last most of the day.

A map showing the treatment area is attached to this letter and will be posted here:  A separate treatment targeting variable water-milfoil may occur later in 2023.  If that occurs, landowners within the treatment area will be notified.

You may contact me by email [email protected] or phone at 207-215-9863 if you have questions about the project.


John McPhedran

Biologist, Maine DEP