A beloved fishing lake near Pinedale now has no fish. To top it off, the entire lake turned red a couple months ago – a deep maroon red.
Land managers and biologists don’t know exactly why, though they think it could have something to do with toxic algae blooms of cyanobacteria, which have been a growing problem in Wyoming’s waters.
Reporting on all of this is WyoFile’s Mike Koshmrl. He spoke with Wyoming Public Radio’s Caitlin Tan about the red lake and if it’s part of a larger trend with warming weather.
Editor's Note: This story has been edited for clarity and brevity.
Caitlin Tan: The lake in question is Little Soda Lake, just north of Pinedale. I grew up here, and I remember people loving fishing there. But as you reported, it hasn't had fish in it for the last few years. Let's start there.
Mike Koshmrl: So, Little Soda Lake is a unique lake in the area because it doesn't have any inflow or outflow. It would naturally be fishless, so the only reason it's been a fishery is that the Wyoming Game and Fish Department (WGFD) would stock it with trout.
But a couple years ago, the local fisheries biologist, Pete Cavalli, went to do some recon ahead of stocking it and noticed that it smelled like “manure,” and it was pretty potent. He thought, “Who's going to want to fish in a lake that smells like this?” Game and Fish made the call not to stock it that year and again in 2024. And then in 2024, things took a turn for the worse.
CT: A couple months ago, the lake literally turned red. In your reporting, you included these photos that look like out of a sci-fi movie. There's a snowy sagebrush landscape, with Pinedale’s Fremont Lake in the distance looking a normal blue, and then in the forefront is this iced over, deep red Little Soda Lake – like the color of a glass of red wine. How did this happen? What's going on here?
MK: So that's the great mystery. All the agencies that are looking into it don't really know with certainty.
My understanding is: In November, a hunter reported it to the Game and Fish, and then they let Bridger-Teton National Forest know. That's where the lake is actually located. And then those agencies started working with the Wyoming Department of Environmental Quality (DEQ).
The theories are, essentially, there's been a long term drought caused by climate change, and water levels have dropped. It could be related to [a] strain of cyanobacteria, which might have all died and then just created this color. But the short story is: They just don't know. They're going to be doing a lot of testing in 2025.
CT: The color change happened relatively quickly, right? We both live here in Pinedale, and we both like to recreate out there. Neither of us noticed the red color in September and October.
MK: I went hiking there last summer and threw sticks in the lake for my dog. It was clearly heavily used by cattle, like a little beat up, but it didn't look like some environmental catastrophe had occurred.
Even into the fall, it looked like nasty water, not something I'd be stoked to get into, but again, it didn't look like something out of a sci-fi movie. And then just in November [is when the lake turned red], which is really kind of odd. Usually, cyanobacteria occur in warm weather, fed by nutrients, and when the water cools down, usually those issues clear up. But in this situation, it was the opposite.
One thing that really stands out to me is just the remarkable turnaround of the historical times, the ’60s, ’70s, ’80s. I've read accounts of people catching trout out of it and loving this little body of water. And it's astonishing to me that now it's like this red-colored cesspool that cannot possibly contain populations of fish.
CT: Do you know why it's hard for biologists to figure out what's going on?
MK: I think that they need to do a lot of different tests that just take time. They have to get samples of the cyanobacteria and then keep those samples alive in order to test the toxicity. And then also, this is not a normal thing.
I talked to Jill McMurray at the Bridge-Teton National Forest, and she said she had bounced it off 15 or 20 hydrologists, and they were just drawing blanks. And so they have to test until they figure it out.
CT: I know you've reported in the past about harmful cyanobacteria blooms. Have you ever heard of them presenting as red before?
MK: I guess that it's possible, some experts say. But it's not normal for that strain of cyanobacteria.
I wouldn't call this the backcountry, but it's relatively pristine on National Forest [land]. I've done some reporting on there being issues in the Brooks Lake Watershed off of Togwotee Pass. These lakes look just picturesque, and they have had really, really high concentrations of cyanobacteria. You wouldn't want your pets or livestock to be in that water. It could be very lethal to them.
I think that there's an increased awareness. There's more testing and so we're finding more of these things. There also could be environmental change that's increasing the prevalence. The Department of Environmental Quality, they have a really handy website where you can see where all the known blooms are in Wyoming. It's a great tool to keep yourself and your pets safe.
I've had a dog get very, very sick from drinking water out of an algae choked pond. He was so sick he couldn't even stand up. I had to carry him in to the vet. There's been documented occasions of dogs dying in places where you just wouldn't guess that it's an issue.
CT: What should people be looking for?
MK: I think that oftentimes the water does look kind of nasty. There'll be a mat of algae. In instances where the water might be more clear, there'll be things that look like grass clippings floating.
CT: Circling back to the red lake, Little Soda Lake. Should people be worried about their drinking water quality in Pinedale? I mean, Fremont [Lake] isn't that far away, which is where Pinedale’s water comes from.
MK: I have not heard anything that would call into question the safety of Pinedale's drinking water.
CT: Do we know if Little Soda is red right now?
MK: I don't know. I do know that after it iced over it stayed red, which is just weird to me. But that was in December. The lake is hard to get to because there's a winter closure around an elk feedground, so I don't know if it's still red. I guess we will find out in the spring when the closure ends, and we can easily get in there again.
For more of Mike Koshmrl’s WyoFile reporting, click here.
For DEQ’s cyanobacterial info page, click here.
