LOVELL, Wyo. — An early bloom of aquatic algae on the Bighorn River has frustrated some irrigators and anglers, who say the masses of green goo are thicker than in recent years.
While algae blooms are common along the river, which runs through northern Wyoming and south-central Montana to its confluence with the Yellowstone River, the plant doesn’t typically appear until later in the season when temperatures rise.
“It usually builds up as the summer progresses,” said fisheries biologist Mark Smith of Wyoming Game and Fish. “But as the weather has gone, we’re seeing algae now we’d normally see around the first of July.”
Smith said the algae is a naturally occurring plant. Aquatic insects feed on it and fish, in turn, feed on the insects.
But some irrigators who draw water from the Bighorn River, and anglers who turn to the waterway for sport, are troubled by the early bloom.
“If you’re a fisherman, whenever you cast, all you catch is moss,” said Bob Croft, president of Friends of Bighorn Lake. “When you’re an irrigator, your equipment gets plugged up. A lot of years we don’t have any problems, but it’s been way too hot for the third week of May.”
Croft said surface temperatures on Bighorn Lake hit 70 degrees this week. Efforts to flush the algae from the river system upstream have only brought the algae downstream, he said.
“When you knock it loose, it all comes down the system,” he said. “When you get into the reservoir, you get the big floating pods of it, this big green mass, and it creates quite an issue for everyone.”
Dennis Fischer of Fischer’s Fishers, a Bighorn River guide and outfitter based in Fort Smith, Mont., said the algae has been present in years past, but it’s rarely appeared as thick as it is so early in the season.
“We always seem to have a little algae bloom in late May or early June that lasts for a few weeks and goes away,” Fischer said. “It don’t know why it’s worse this year than other years. A lot of people are complaining about it, but they do every year when it blooms.”
Fischer believes that with high water flows over the past two years, the algae hasn’t been as noticeable. But with low snowpack and summery temperatures early, river and reservoir systems are running low, and the algae is more prevalent.
“You’ve got to have it,” Fischer said. “The bugs grow in it. We could just use just a little less of it.”
Smith said the irrigation district out of Worland requested a flushing about two weeks ago in an effort to move the algae downstream. Game and Fish generally requests a flushing in March to clean out gravel beds to help fish during the spawn.
Smith said it’s likely the algae will build to a certain level before falling back.
“The Bighorn is pretty productive that way,” Smith said. “It has the right combination of bottom substrate, temperature and light. It has the right conditions to produce the algae, but it’s unusual to have that much this early in the year.”