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Navigating Troubled Waters


It's interesting to hear Snake River fly fishers of different generations debate the quality of the fishing now compared to 40 years ago. Old-timers rave about the lack of pressure back then, and the good numbers of large fish in the system. A younger generation points to electroshock data that suggests in some cases the fish numbers are stronger now. Some of them believe we are fishing in the Snake's golden age.

My opinion regarding the health of the fishery tends to be similar as that of this younger generation. The Snake is unquestionably healthier now than what it was in the 1960s and 1970s. Flows from Jackson Lake Dam are today managed more progressively. Abrupt ramp-downs that left invertebrates and trout trapped in side channels to die are a rarity nowadays.

Catch-and-release has led to far less harvest than in previous decades. There has also been a lot of rehabilitation work done on spawning creeks and other tributaries. The result is a more balanced ratio in terms of size and age structure of trout. Forty years ago, a day of fishing often resulted in a bunch of 12-inch and smaller trout, with a couple of bruisers over 19 inches. Today, there is a robust population of 12- to 18-inch cutthroat, as well as a good number under and over that size. And this is despite the stocking on hundreds of thousands of non-native rainbow and brown trout which together represent less than 1% of the total gamefish abundance.

The Snake River’s cutthroat have thrived despite getting their kicked in the teeth with all the crap – disguised with terms like “progress” and “improvement” – that brought so many other native trout populations in North America to their knees. This is a point of pride for many area fly fishers.

And yet I do not think many, regardless of the generation they represent, have confidence this will remain the case. This is due precisely to the changes we are witnessing on our waters.

Indicators of climate change are everywhere in Snake River country. Our moose, a critter built for cold winters, are in decline. Pikas are retreating to higher elevations. Burn scars from forest fires are larger and more numerous. The Siberian-like cold snaps that occurred somewhat regularly – - 40 in 1971, - 61 in 1978, - 54 in 1990 - appear long gone now. My records show the last time the Jackson weather station recorded – 30 or lower for consecutive days was in January of 2008.

The waters of the Snake River drainage have not been spared. No where is this more evident than in our rising water temperatures.

I began actively observing water temps on the Snake River and other area waters in 2003. No, it wasn’t warnings by climate scientists or politicians that sparked this move on my part. Rather, it was the concern over the issue raised by fishery biologists and fellow anglers.


In August of 2003, I measured the Snake River surface temperature at 64 degrees downstream of Deadman’s Bar. That was shocking. Despite how warm the water was feeling, I still couldn’t believe it was actually over 60 degrees.

In 2007, the highest reading I took came in at 66 degrees. This was above the Gros Ventre River confluence. Again, this was at the surface.

In 2008, I began using the gauge at Moose, Wyoming, for more reliable readings than my very basic stream thermometer. This monitoring station went online with temperature parameters the previous October and measures near the middle of the water column. This little change was just that – little. While it might report data a couple to a few degrees cooler than the surface, all those reading on the warmest days of summer were coming in over 60 degrees.

By 2015, the Moose gauge was recording water temps at 68 degrees for the first time. 2021 saw the gauge knocking on the door of 70 degrees. And then, in 2022, and for the first time, water temperatures exceeded 70 degrees. It did so over a dozen times.

The impact of warm water on fish is well established in the research literature. Trout typically require four times the amount of oxygen at 67 degrees as they do at 39 degrees. Nutrient consumption and growth rates decline with higher water temperatures. Increased water temperatures also lead to a decrease in serum glucose, triglycerides, and important enzymes, which leads to immunity, digestion, and growth impairment.

Evidence of the impact of this warming exists throughout the region. Before the guage on Wyoming’s New Fork River lost its temperature monitoring abilities in 2020, 72 degrees was common for weeks on end most summers. The Madison at W. Yellowstone can hit 74 degrees regularly during hot summers. Longtime Montana outfitter Craig Mathews has reported an increase in white Miller caddis, an invertebrate that thrive at higher water temperatures. Neon green blooms of filamentous algae on the Snake are clearly visible to motorists crossing bridges at Wilson, Hoback, and Swinging Bridge. Toxic blooms on Idaho’s Blackfoot Reservoir have been detrimental enough to bring fishing to an abrupt halt in August.

And more than anything else, runoff on just about every stream is occurring earlier than it used to. When I started guiding in 1991, guides would always say “runoff on the Snake River starts on May 10th. And if it didn’t start on May 10th, it would start on the 11th.” For the most part, that really was when runoff commenced most year. Today, runoff has as much of a chance of starting the last week of April as it does the first week of May. In fact, the latest I have seen runoff start in the past dozen years is May 5th.

Veteran Snake River guide Phil Steck once said, “If global warming is happening and you fish or ski, Jackson Hole is the place you want to be.” There is still a lot of truth to that when compared to Montana or Utah or Colorado. Nonetheless, things are changing. And as fly fishers, we are adapting.

While 70-degree water temperatures used to be the threshold, most anglers and management agencies now mark 68 degrees as the tipping point where fishing should come to an end. On our streams, that’s around 3pm to 7pm. So we are starting earlier and trying to end our day by 3pm, maybe 4pm at the latest.

Guides and anglers are adjusting their seasonal practices as well. August water temperatures feel so dire that some are abandoning the month altogether. Others are transitioning to nearby warm water venues where fish like bass and carp are the target species and there is less of a feeling of doing harm. And of course, we are seeing more of an emphasis on winter on streams like the Snake, the South Fork, and the Henry’s Fork.

This all sounds rather sad, almost like the ramblings of an eternal pessimist. Yet I should be optimistic simply because I have seen the positive reaction of the fishing community and various agencies to the changes we are seeing. Major area rivers and their tributaries have more water quality gauges now than ever before, thanks in large part to nonprofits that fund them. Agencies like the Bureau of Reclamation and USGS have open lines of communication with state fishery management departments regarding flow, temperature, and other water quality parameters. And the vast majority of anglers follow the recommendations of fish and game departments regarding when to cease fishing activities, despite not being legally required to do so. These are major changes compared to 40 years ago.

So, yes, I am an optimist. That is because I fish and I ski. And like Phil Steck said, if these endeavors are a major part of your world, Jackson Hole is the place you want to be.


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