Flathead Lake Water Quality Maintains High Marks, Citizen Science Project Grows

October 15, 2019

Citizen Scientist and Flathead Lake Open Water Swimmers co-founder Mark Johnston stores freshly harvested water samples from Polson Bay. (Photo courtesy Mark and Dana Johnston)  POLSON – The waters in public swim areas at Flathead Lake have been ranked clean and safe for swimming by a citizen science project for the second consecutive year.

“The sampling was great this season,” said Mark Johnston, founder of the Flathead Lake Open Water (FLOW) Swimmers and a driving force behind the Swim Guide Citizen Science Project at Flathead Lake. “The recreational water quality of Flathead Lake remains exceptional.”

The Swim Guide Project is a collaborative effort among the Flathead Lake Biological Station, the Confederated Salish and Kootenai Tribes and the FLOW Swimmers United States Masters Swimming Club in Polson, along with funding and effort from numerous Adopt-a-Beach partners.

The project is a community-driven water quality monitoring program, created to provide water quality information on the Swim Guide website and smartphone app (https://www.theswimguide.org/). The Swim Guide helps users easily find beaches open for public swimming and their water quality.

According to the Swim Guide, a beach is marked red – or unsafe for swimming – either when the average of two consecutive single sample results are equal to or over 100 colony-forming units (cfu) of bacteria, such as E. coli, per 100 milliliters of water, or, if a single sample exceeds 320 cfu per 100 mL of water.

Of the 110-plus tests conducted by the Flathead Lake Biological Station in 2019, the highest two-day average taken from any sample site at Flathead Lake was 75 cfu per 100 mL of water, while the highest single day result was 150 cfu per 100 mL of water. None of the results come close to exceeding Swim Guide program standards.

These results are notable, as is the expansion the Swim Guide Project has experienced at Flathead Lake over the past three years.

Two years ago, when the Swim Guide Project first came to Flathead Lake, it focused on monitoring three public swimming areas in Polson – Riverside, Boettcher and Salish Point parks. A year later, the number of monitoring sites swelled to six locations, adding Wolf Point, Elmo and Blue Bay tribal parks.

Now, the number of monitoring sites in the Flathead Lake Swim Guide Project has doubled again. It now boasts 12 monitoring sites, including Volunteer Park in Lakeside; Somers; the City Docks in Bigfork; Flathead Lake State Park – Wayfarers and Yellow Bay Units; and the Bio Station’s cabin shoreline.

Over the summer, samples were collected from each location every one or two weeks and sent to the bio station’s Freshwater Research Lab, where they were processed for E. Coli, a bacteria that can be transferred to normally clean swimming areas from waste – either from humans or local wildlife. The possibility of higher E. Coli levels increases on hot, stagnant days or after periods of heavy rainfall.

The results were returned to their respective citizen scientists, who then posted the information to the Swim Guide app.

To help accommodate the growth of the Swim Guide Project, many area small businesses participated to help offset the costs. These businesses include Alpine Design, UBS, Riverside Recreation, Flathead Lake RV, Glacier Perks, Rocky Mountain Outfitter and Sail Inn Marina. Nonprofit organizations like the Flathead Lakers and Greater Polson Community Foundation also have provided support for the project.

To learn more about the Swim Guide Project or to find out how you can participate, visit the FLOW Swimmers website at www.FlowSwimmers.com. The Swim Guide app is online at www.TheSwimGuide.org

The Bio Station’s Freshwater Research Laboratory is an ecosystem science facility providing grant, contract and fee-based analytical services. It offers analyses on water, soil, air, biological and radiochemical samples. For more information about FLBS services, visit https://flbs.umt.edu/newflbs/services/freshwater-analyses/.


Contact: Tom Bansak, assistant director, Flathead Lake Biological Station, 406-872-4503, tom.bansak@flbs.umt.edu; Ian Withrow, FLBS media/information specialist, 406-872-4544, ian.withrow@flbs.umt.edu.