An update from the City of Sammamish

Dear Sammamish residents,

Thank you for your sincere concerns regarding the planned water lily removal at Beaver Lake.  The herbicide that is proposed is not Round-up.  The Beaver Lake Management District has tried to address many resident questions and concerns about the use of glyphosate.  Please see additional information provided in the below link.

Best regards,



Tawni Dalziel, P.E.

Sr. Stormwater Program Manager

Public Works Department

City of Sammamish

801 – 228th Ave SE

Sammamish, WA98075

Phone: 425-295-0567




A Message from the President of the BLCC

Regarding the use of Glyphosate in Beaver Lake                                                                                     8/6/2017

I realize that I probably won’t change your mind about using Glyphosate to treat the water lilies, but there are a couple misconceptions in your emails that should be addressed.

I agree that Roundup would be harmful if used, but saying Glyphosate is Roundup is like saying all dogs are alike. There are two parts to herbicides used for weed control: the chemical that kills the plant and the chemicals that bond the chemical to the plant. Roundup is used for land-based weeds and its bonding agents are quite different and more toxic than the ones used in Glyphosate which is used on water-based weeds.

The treatment of water lilies with Glyphosate is a foliar spray that goes on the floating leaves of the plants. No chemical is put into the water column like some other aquatic herbicides. Glyphosate is also broken down fairly quickly by microbial activity and bonds tightly with sediments and soils so it is not very mobile. In other words, it stays where it’s sprayed.

Glyphosate itself has low toxicity to mammals, fish and birds. Any aquatic herbicide (legally) applied in Washington must be approved by the Washington State Department of Ecology and deemed safe for use in aquatic environments. There are no swimming, drinking or irrigation restrictions to waters that have been treated with Glyphosate. Many other aquatic herbicides have restrictions such as no swimming for 48 hours or do not use water for irrigation for 30 days.

The average person would need to drink 12 ounces of straight herbicide all at once for there to be harmful effects. There would need to be prolonged dermal (skin) exposure to 12 ounces of just the herbicide alone. A person would need to directly inhale the herbicide fumes for 4 hours to experience harmful effects

On a personal note, I have lived on this lake for 30 years and during that time I have been actively involved in several different efforts to protect and improve the quality of the lake. I have done battle with the water lilies for those same 30 years using several different manual and mechanical methods only to see my efforts fail in controlling the lilies spread. Glyphosate is a safe, economical and successful way to manage the water lilies. I would not support the use of Glyphosate if there was any tangible evidence that it would be harmful to the lake, the animals on and in the lake and the people who use the lake.

Joe McConnell