Harmful algal bloom discovered at Canyon Ferry

Canyon Ferry Lake
Posted at 10:30 AM, Aug 24, 2022

CANYON FERRY — A harmful algal bloom has been found a Canyon Ferry Lake according to Lewis and Clark Public Health Environmental Division.

LCPH says the bloom was tested near the Hellgate Campground Day Use Area and Boat Launch on Friday, July 22. Testing indicated a level of microcystin at or above 10 ppb. For reference, both the state of Montana and the EPA recreational water recommendations use 4 parts per billion (ppb) as the warning level for microcystin toxin.

Recreationists are encouraged to exercise caution to avoid an algal bloom that could potentially produce toxins that pose a risk to people, pets, and livestock. Bluegreen algae blooms often look like pea soup, grass clippings, or green latex paint. The algae are usually suspended in the water or appear as floating mats; they do not grow from the bottom with roots like other water plants.

LCPH will retest for microcystin in the coming weeks and will continue testing in Canyon Ferry and other Lewis and Clark County water bodies as needed over the course of the summer.

Because tracking rapidly changing conditions in every body of water is not feasible, LCPH wants people to be informed enough to make their own recreational decisions. They also ask the public to help by reporting HABs so that they can respond quickly and hopefully prevent people, pets, and livestock from getting sick.

In past summers, algal blooms have been identified in several Lewis and Clark County surface waters in the past including Lake Helena (including the north side of the causeway), Hauser Lake, and Canyon Ferry Lake. Ongoing high temperatures could increase algal bloom activity in the county this summer.

Suspected HABs can be submitted, including photos, to the website: This site also has a live map of reported HABs and identification information. When a HAB is reported to either DEQ or directly to Lewis and Clark Public Health, it is investigated to determine whether the bloom is nuisance green algae or potentially toxic blue-green algae.