The news of the great catch spread like wildfire through the West. Henry’s Lake, a shallow reservoir in eastern Idaho nestled against the Montana border, delivered another legitimate trophy: a 36-inch hybrid rainbow trout.
On Oct. 4, angler Hailey Thomas of Rigby, Idaho, caught the monster trout while fishing the famous trophy-producing lake with her husband and two sons. According to local news, the water was a bit discolored and the fishing had been slow. Just as her husband, Shane Thomas, raised the anchor to move to a new location, the monster trout came calling. The fish beat the Idaho hybrid trout record by a full six inches, and the fish’s girth was more than 21 inches.
A beast for sure, and good for Hailey – it’s a catch of a lifetime that few others will experience.
Unfortunately, Lake Henry may not be the place to enjoy those fishing years from now. Just three days after Hailey threw her trophy, the Idaho Department of Health and Welfare issued a family advisory to anglers and boaters who use Lake Henry for recreation: The lake was in the midst of a bloom of toxic blue-green algae and state health officials. he warned against even touching the waters of the lake at high altitudes.
According to a news release from the state DEQ, water samples collected from the shore of Lake Henry showed the presence of the cyanobacteria species Microcystis, Dolichospermum, and Aphanizomenon. All three bacteria can produce dangerous toxins that can be harmful to people, pets, and livestock, and the DEQ warned that people with liver or kidney damage are at increased risk of illness.
This is Idaho, a politically red-hot state where everything from science to election results is regularly questioned, there was no mention from the state DEQ of the cause of the algae bloom, other than these species of blue-green algae “are a natural part of Idaho’s water bodies” that can bloom to dangerous levels when the climate and water temperatures warm. The cause of the warming? None mention in the state’s health advisory, aside from the seemingly innocuous increase in water temperature.
Unfortunately, this is nothing new for Henry’s Lake. It is a shallow reservoir and has prolific weed beds that provide cover for giant trout and great habitat for obnoxiously abundant aquatic insects. It gets hot in the summer sun, no doubt.
The lake has been subject to documented blue-green algae blooms every summer and fall since at least 2017. And it’s not alone. Many of Idaho’s famous reservoirs have experienced these algal blooms, including Cascade Reservoir, a popular fishery near McCall in western Idaho.
But, over the past two years, the bloom has spread to Island Park Reservoir, an irrigation reservoir on Henry’s Fork near the top of the river’s drainage (Henry’s Lake is not directly in Henry’s Fork). This is notable because Island Park Reservoir is large: at full pool, it covers 8,400 acres of high-elevation real estate.
But it’s not exactly a surprise, at least to scientists who predict more of the same, as the climate continues to warm and water temperatures, even in reservoirs that are 6,500 feet up, continue to rise. It could also be one of the first signs that climate change is affecting the waters of the West to the point where even taking a swim can be bad for human health. Although climate change is not mentioned in the Idaho DEQ’s health advisory, it doesn’t take much to make the connection between algal blooms and a warming climate.
Over the past two decades, water temperature advisories have become the norm on trout streams in the West. Documented die-offs of trout and whitefish due to warm water or bacterial and algal blooms as a result of warm water have persisted for years.
But now we talk about human health. And we’re talking about lakes that have serious economic benefits for communities, like Island Park Reservoir, which is very popular with boaters, jet skiers, swimmers, and fishermen. Blue-green algae blooms are no longer isolated incidents in the Rockies: they are, predictably, spikes in water temperatures that are enhanced by climate change and resulting droughts.
As of this writing, Island Park Reservoir is less than half full and 4,000 acre feet lower than a week ago. Other reservoirs in the area are also dry. Palisades Reservoir, on the nearby South Fork, is only 6% full at the time of this writing; it has actually fallen 1,000 acre feet in the last week.
The upper end of the reservoir is completely dry, leaving important migratory tributaries for fall brown trout exposed to predators such as pelicans and raptors. This lake is also important to the recreational community of eastern Idaho and western Wyoming. Fortunately, there have been no water quality warnings from DEQ for Palisades.
Sometimes, for issues to be fully understood, the impact needs to be felt by more than just one user group. As fishermen, we have come to understand climate change and what is happening to our rivers, lakes and streams because we are directly affected. Now that blue-green algae blooms are beginning to spread in lakes and reservoirs where more and more people come into direct contact with the water, others may begin to understand the serious challenge posed to the West by a warming climate.
In the case of Henry’s Lake and Island Park Reservoir, impacts could be widespread. There are thousands of lakeside cabins and second homes on the shores of both lakes; they are tourist destinations for visitors who arrive in the area; it’s close to Yellowstone National Park and the fishing, ATVing, Nordic skiing and snowmobiling are legendary. But if you’re a Lake Henry vacationer and you’re not sure if you can touch the water, does that change the appeal? You bet.
It also changes where you spend your money. Local gas stations, lodging establishments, fly shops, restaurants, and campgrounds may be in for a rude awakening if water-motivated tours take a bath because… well because taking a bath could make you sick the people. Who wants to drop a line and chase giant trout if touching the water can be dangerous?
This isn’t just an Idaho thing. Blue-green algae is a slimy bloom across the country. As it blooms, it absorbs more sunlight, making the surrounding waters even warmer and more toxic. Idaho is just the latest on their list of victims.
But what is alarming is that he is not to blame. It is nothing more than a symptom of a much bigger problem. And until state health departments and environmental safety departments have the stones to let the citizens they’re trying to protect know the whole story, it’s not likely to get better.