A draft management plan for reducing toxic algal blooms in Lacamas, Round and Fallen Leaf lakes envisions a $4.1 million, 10-year effort including chemical neutralization of phosphorus in Lacamas Lake.
The plan was unveiled Sept. 28 by Camas Public Works Director Steve Wall and Geosyntec consultant Jacob Krall following a yearlong water-quality study of the lakes.
Making the lakes safer for recreating and cleaning up the 67-square-mile Lacamas Watershed — the main source of phosphorus and nitrogen that feed algae and contribute to the toxic blooms — will take long-term solutions and assistance from city, county, state, nonprofit and community stakeholders, Wall said.
The study found that Lacamas Creek is the dominant source of water and phosphorus loading to Lacamas and Round lakes, representing approximately 90 percent of the water and 72 percent of the phosphorus loading to Lacamas and Round lakes.
It also found that the most elevated total phosphorus concentrations were near the bottom of Lacamas and Round lakes, at concentrations higher than measured in studies and measurements taken in the past 30 years.
The plan recommends treatment efforts be focused on Lacamas Lake. It said Round Lake, which is downstream from Lacamas Lake, may see benefits from treatments upstream.
The report also noted that, while Fallen Leaf Lake has similar levels of phosphorus to Lacamas and Round lakes and should continue to be monitored, it had not developed same type of algae that contributes to the toxic algal blooms known to be unhealthy to humans and animals.
Wall said the efforts will be highly dependent on results of a state Department of Ecology investigation of nutrient-loading sources within the Lacamas Watershed. Once Ecology has completed its watershed source assessment later this year, it will begin putting together a restoration plan, Wall said, which will look at improving water quality throughout the watershed and, in turn, in Lacamas and Round lakes.
Wall said he expects the state’s alternative restoration plan for the watershed, which will likely not be completed until at least 2025, to include strategies for repairing and inspecting septic systems, planting and doing mitigation work along creek areas to provide shade, helping to restore eroding stream banks, and addressing agricultural lands and stormwater systems.
Until then, the city of Camas’ Lakes Management Plan will provide short-term options for preventing toxic algal blooms in Lacamas Lake — a popular destination for boaters, kayakers and paddleboarders — and nearby Round Lake, which is open to only non-motorized watercraft.
Three-part strategy
The draft plan offers a three-part management strategy for the lakes, including:
- The annual removal of phosphorous from the lakes’ water columns — the space from the surface to the bottom of a lake — using chemical treatment beginning in the spring of 2024, at a cost of $1.8 million.
- Deactivating the phosphorus in sediments using chemical treatment over the next five to 10 years, beginning in the spring of 2024, at a cost of $1.3 million.
- Reducing phosphorus loading from the Lacamas Watershed “through continued partnerships with Clark County and other regional and state organizations.”
City staff and consultants have recommended using either aluminum sulfate (alum) or a product known as Eutrosorb WC to remove phosphorus from Lacamas Lake, noting that alum has “been applied to numerous lakes in Washington” but could require “buffering to maintain a pH range that will prevent the formation of compounds toxic to aquatic life,” while Eutrosorb WC “is a more recent product and is believed to have lower risk to aquatic organisms.”
The draft plan notes that alum is permitted under Ecology’s current permitting system, while Eutrosorb WC would require the city to receive an experimental permit.
The second treatment recommendation focuses on binding and deactivating the phosphorus already present in sediment found in Lacamas and Round lakes using either alum or another product called Eutrosorb G for the next five years, beginning in the spring of 2024, with future treatments “dependent on results and monitoring.”
Krall said lake enthusiasts should notice a difference in the number of toxic algal bloom warnings after the first in-lake chemical treatments.
“You would see benefits in the first year,” Krall said. “There will be a reduction in algal blooms that first year.”
The draft management plan estimates it will cost around $4.1 million for 10 years’ worth of in-lake chemical treatments, monitoring and public outreach. In addition to the lake treatments, it would cost $500,000 for 10 years’ worth of monitoring and $50,000 for 10 years’ worth of public outreach to help reduce nutrient loading from the Lacamas Watershed, which will “reduce in-lake treatment costs over time.”
The city has $515,000 from a state grant provided by the 2023-25 State Capital Budget to help cover some of those costs.
Wall recommended that people who are interested in the issue read the draft plan on Engage Camas and send comments to Wall at swall@cityofcamas.us. The city will also receive feedback from Clark County, the state, and other agency and nonprofit stakeholders before sending a draft Lakes Management Plan to Ecology for the state’s review and approval.
