Montana Public Radio

Health Department Warns Of Harmful Algal Blooms

Jul 23, 2019

State agencies are warning of increasing "pea soup" looking algal blooms in Montana’s freshwater lakes and reservoirs.

The blue-green algae are usually suspended from or joined to floating mats in the water, and can produce toxins that damage the skin, liver and nerve cells.

A warning sign for waters that may contain toxic algae.
Credit Montana DEQ/Montana DPHHS

The Montana Department of Environmental Quality and Department of Public Health & Human Services, in a joint announcement today, said that scientists believe the blooms are occurring at more locations, with increased frequency and longer duration.

The agencies say potential causes include warmer water temperatures, longer summer growing seasons and increased nitrogen and phosphorus runoff from a variety of human activities.

Algal blooms can also look like grass clippings or green latex paint and not all varieties of blue-green algae are harmful.

You can report potential harmful algal blooms to the DPHHS here.