Friends of Cottage Lake

Phosphorus treatment – scheduled for Thursday, May 7th, 2026 – no irrigation or recreational restrictions – signs will be placed in yards around the lake May 6th. This is a big treatment, so the motor boat will be out on the lake for most of the day

Next Meeting – still TBD, but we will be at the library for an event on May 30th, 2026

State of the Lake 2024: Friends of Cottage Lake has been researching water treatments to remove phosphorus from the water and other treatments that might reduce harmful blue-green algae blooms. This year, we hope to try a treatment in partnership with Aquatechnex. Based on their analysis of the lake (they did additional lake and sediment sampling in 2023), the best treatment given our budget is to do two “water column stripping” treatments with Lanthanum (in May and July) to remove phosphorus from the water column with an estimated cost of about $56,000.00. We plan to have a community meeting in early May and then a spring fundraiser at Bassetti’s Crooked Arbor Gardens on Sunday, May 19, 2024. See the State of the Lake 2024 letter for more details.

Water Lilies – last treated in 2017 – watching the remaining lilies – no treatment currently planned.
See the water lily page for more info.

Fish Stocking information for 2026:
Cottage Lake Fish Stocking (including information on the fishing derby in 2026)

Join Friends of Cottage Lake on Facebook:
Click here to apply to join the private group or check out our public page here: https://www.facebook.com/FOCL.Woodinville

Who we are:

Friends of Cottage Lake (FOCL) is a non-profit, community-based group committed to improving and defending the health and continued enjoyment of Cottage Lake in Woodinville, WA.

We are currently working with King County to apply for grant money to help fund various lake improvement projects. In the summer of 2005, our lake was chosen as a recipient of a Centennial Clean Water Fund grant—this grant targets the phosphorus problem and funded water quality monitoring and community outreach programs for 5 years.

FOCL is also working with the community to deal with the water lily problem and the Eurasian Milfoil infestation on Cottage Lake. See the links for more information.