By Al Kraus
Gian Dodici, a U.S. Fish and Wildlife Service biologist, told me that “as average water temperatures continue to increase in our cold-water streams, it is imperative that we identify reaches with cold-water inputs. Once identified, these reaches need to be protected, and when appropriate, enhanced through the addition of in-stream habitat, riparian cover, and other practices, to help maintain the ecological integrity of the cold-water system.”
Developing a more focused approach to combating rising water temperatures is critical, but to address these problems effectively, more far-reaching strategies must be considered. For example, for many years conservationists have fought to have dams removed throughout the United States. Perhaps, in view of the newly emerging threats, it is now time to rethink this position. Some of our most productive trout streams are tailwaters fed by cold water from large reservoirs. Examples are numerous, including the West Branch of the Delaware in New York, the Yakima River in Washington, and the North Platte in Wyoming. In many cases, reservoirs provide more consistent flows of life-giving cold water to the trout within these rivers and help protect them from emerging global warming and reduced water level problems.
At least on a case-by-case basis, perhaps we need to start rethinking our position regarding dams and reservoirs, and add them to the list of tools we might sometimes use to help preserve and protect cold-water fisheries. In the future, we may even want to propose the addition of new dams to both protect valuable cold-water fisheries and provide more environmentally friendly power. Yes, many river systems and many migratory species, such as salmon and steelhead, have been adversely affected by poorly placed and designed dams. For example, dams have severely degraded the natural habitat, migration, and spawning in the Columbia and Snake Rivers and their tributaries. Nevertheless, perhaps in some cases, dams or similar structures that are properly designed and placed can help provide more consistent flows of cold water to species that would not otherwise survive under the onslaught of global climate changes. I believe we have reached the point in some areas where we may have to decide whether it is better to have wild running rivers, where many stretches of a stream are no longer habitable by salmonids because of elevated water temperatures and/or low flows, or use dams and impoundments to help to counteract the negative impacts of global climate change. Desperate times sometimes require desperate corrective measures.
In places, annual precipitation (including snowpack) is lower than historical levels and seems to be decreasing further. Moreover, high-intensity, short-duration rainfalls are increasingly common, often causing rapid runoff that does not allow soil adequate opportunity to absorb the moisture. Likewise, snowpack in western states tends to melt faster than it did during any years of record keeping. On the other hand, lower-intensity, longer-duration rainfalls, and gradually melting snowpacks, are generally absorbed into the soil and replenish water tables, which feed streams through seeps and springs, which help to keep rivers full. Impoundments can help mitigate for these conditions.
Changing our stance regarding the utilization of impoundments would have to be predicated on the concurrent employment of the best available technologies to minimize the negative impacts on migration and spawning. And we would need to continue working toward designing even better innovations to improve in-stream migration for fish while at the same time working to offset the increasing threats posed by climate change. We must develop strategies tailored to individual watersheds.
A 2023 NASA study, “The Effects of Climate Change,” indicates that, “The earth will continue to warm and the effects will be profound.” Former NASA administrator Bill Nelson says, “Between record-breaking temperatures and wildfires currently threatening our centers and workforce in California, it has never been more important to understand our changing planet.”
Furthermore, a 2002 report by Kirkman O’Neal for the Natural Resources Defense Council, entitled “Effects of Global Warming on Trout and Salmon in U.S. Streams,” predicted that, “by 2090 18% to 34% of locations currently suitable for cold-water fish will become too warm to provide suitable habitat.” If I looked at this report back in 2002, I probably would have thought this number was too pessimistic; however, given the current warming trends in many streams, it appears that this prediction may have been optimistic. Rivers in relatively flat parts of the United States (like the Cohocton River), where the trout cannot seek cooler water at higher elevations or get life-giving cold water during the summer from snowpacks, are in the greatest danger from global climate changes.
However, based on information gleaned from the internet, conservationists in many mountainous states are also already observing problems related to global warming and seeking ways to protect and preserve their most vulnerable cold-water species better. In addition to rising average water temperatures, these states have to contend with reduced snowpacks, frequent wildfires, and drought conditions. In what might be viewed as a harbinger in our mountainous states, on June 6, 2023, Eileen Rice, with the Montana Fish, Wildlife & Parks (MFWP), issued the following statement: “Trout populations in many streams in southwest Montana have seen decline in recent years, and research continues to point to perennially low stream flows and high water temperatures as contributing factors.” And on July 26, 2023, MFWP also issued a proposed emergency regulation for smallmouth bass—because of rising water temperatures, these nonnative fish showed up in the lower Bitterroot River. The agency explains, “Smallmouth bass are a predatory and adaptable species and could have a long-term impact on this cold-water fishery.”
The purpose of this article is to raise the red flag regarding these rapidly growing threats to our cold-water fisheries. We may need to modify our focus somewhat because we can no longer really protect trout populations in many streams by just trying to restore damaged habitats. Global climate changes dictate that we can never go back to the way things were in the past; the old norms are gone forever. Now is the time to reassess what is going on in our cold-water fisheries, consider the new challenges, and reevaluate how best to move forward.
Lead photo: On the Cohocton River in New York, volunteers were able to persuade some farmers to cede a margin of their fields so trees could be planted along the banks. Cooperative efforts such as this, which rely on fostering good relationships with landowners, are critical for conservation efforts in many places. Photo by Al Kraus.
