SNOHOMISH — The city is investing in Blackman Lake.
Just last week, divers hired by the city pulled invasive curly leaf pondweed out. This weed first was spotted in the lake in 2021.
Further into the future, the city hired an environmental consultant for $104,000 for its expertise to write a plan for reducing toxic algae blooms. Herrera Environmental is doing a year-long study; its report should be done by 2024, city engineer Yosh Monzaki said.
One focal point will be to reduce the amount of phosphorous nutrients in the lake that empowers algae to thrive.
The lake off of 13th Street can use any help it can get.
As of Thursday, Sept. 8, the lake remained under a toxic algae watch, from signs posted at the lake. It's been over a month since the warnings went up Sunday, July 24. The lake was last tested Aug. 29, according to records published on the state's toxic algae database.
Algae thrives under bad water conditions. Among all algae types, it is the blue-green variety that prompts warnings because it has toxins that can make people and animals sick.
Kay Ditzenberger, a Blackman Lake advocate who lives along the lake, says flow is essential for the lake’s healthfulness. Without good flow to consistently flush the lake, chemicals that seep in just swirl around, she described.
People’s pesticide chemicals that seep in could be boosting the lake’s phosphorous levels. Lake residents along the shoreline spray glyphosate regularly to control shoreline lillypads for the property maintenance.
No chemical tests have been done for Blackman Lake, and none are planned, the city said.
A chemical analysis of the lake will help fill a critical part of the picture of the lake’s situation, Ditzenberger believes.
“Remediation is good, but it does nothing to prevent the lake’s death,” Ditzenberger said.
Weather controls flow, Monzaki said.
Blackman Lake is a natural lake fed by surface water and ground water. Water flows in from a small watershed of creeks plus two channels. The watershed goes as far north as the corner of 30th Street SE and state Route 9, an area parallel east to the Snohomish Station shopping plaza.
The city has a stormwater channel that is part of the intake. Anything put in the storm drains could end up here.
Lake water is discharged through four pipes that feed to the Snohomish River. Ultimately, everything goes to Puget Sound.
The city further improved outflow in 2020 by installing overflow spots which spill over water when the fish screens get blocked by debris.
The capacity in number of gallons flowing out has improved thanks to a channel along Avenue A. The city does not have flow meters for lake intake.
