Repairing Blackman Lake: The next steps to try to curb lake’s decline
Doug Ramsay photo
Doug Campbell of Snohomish uses a measuring tool to take a sample of water from near the center of Snohomish's Blackman Lake on Wednesday, Dec. 14. The work is part of a monthly water test volunteers such as Campbell are doing for the city to create a years-long catalog of water quality information. This information will be used for strategies to help the lake.
SNOHOMISH — Doug Campbell steers the rowboat toward the middle of Blackman Lake.
He opens a pneumatic cylinder and lowers the tube into the depths until a weight slides down the cord and snaps the lid shut.
Next, he lowers a black-and-white Secchi disk into the water until it can’t be seen. Campbell notes the depth at which the disk disappears, then repeats the procedure.
Soon the water sample and Secchi data will be on their way to a laboratory as part of a city agreement with Herrera Environmental Consultants.
The city hired Herrera this fall to begin monitoring blue-green algae blooms (cyanobacteria) in the lake and recommend ways to manage the toxic flora.
“It’s pretty much a year-round problem,” said Campbell, who has lived on the lake since 2016. “It’s nasty stuff.”
Campbell is one of about a half dozen volunteers who are collecting water samples and recording observations each month for Herrera through 2023.
He and wife Marci Gionet also belong to Friends of Blackman Lake, a group of homeowners and stakeholders concerned with Blackman’s diminishing water quality.
Over the past three decades, the lake has declined from a rating of “good” to “fair” in three key health indicators: algae blooms, water clarity, and phosphorus content in its lower waters.
The city posted signs for 42 weeks during the past two years warning against swimming in the lake due to toxic blue-green algae blooms.
Between 2008 and 2019 it had posted such warnings for a total of two weeks.
There are a pair of city parks on the lake — Hill Park and Ferguson Park — as well as private homes and uninhabited stretches.
“The blue-green blooms seem to be happening more and more frequently,” said city engineer Yosh Monzaki. “We’re working on a way to address that.”
The Herrera plan is the first step.
Snohomish has used volunteers for years to take water samples each summer, but the water quality has never been professionally monitored for 12 consecutive months like what Herrera will do through lab testing.
Main objectives of the Herrera study include reducing phosphorus pollution (which will lower toxic algae), eradicating curly-leaf pondweed, and determining if bacteria, caused largely by waterfowl waste and septic systems, is a significant concern.
Washington State classifies Blackman Lake as “impaired” for bacteria under the Clean Water Act, but Snohomish County has not collected enough information on the topic.
Once the Herrera analysis is completed, the city will explore management options.
These could include adding more oxygen to the water, hiring divers or buying equipment to harvest unwanted lake flora, or treating the lake with herbicides, Herrera representatives discussed.
But the ultimate solution, insists Friends of Blackman Lake, is to improve the waterflow in and out of Blackman.
This would include more expensive alternatives such as dredging the lake bottom, drawing down the water level, or piping in water from another source.
“We need to be ready for (the Herrera report) results,” said Brad Steiner, a lakeside homeowner and Friends member.
The city needs to start identifying funding sources and preparing to act quickly upon Herrera’s recommendations.
“If we wait, we’ll be two years behind the eight ball,” Steiner warned. “Our focus is on building common engagement and positive passion. We want to be as proactive as possible.”
Blackman Lake facing difficulties for healthy longevity
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