When putting together the highlights for my presentation on the Harriman State Park Temperature Monitoring Project this week, I thought it would be helpful for me AND you, reader, to summarize some major points I wanted to make! I hope these things can help. These 17 temperature logging sites have shown us that Ranch temperatures are anything but static, based on variations of the factors below.
First, water temperature is impacted by so many things, but for the Henry’s Fork, we can attribute changes in temperature to three main things: solar and thermal radiation, outflow and drawdown from Island Park Reservoir, and the impact of tributaries and springs. Solar and thermal radiation penetrate Henry’s Fork easily because of its wide and shallow structure, and especially on hot summer days like the ones we’ve seen. When we have high outflow and net positive drawdown from Island Park Reservoir, the water flowing out tends to be warmer. The cool water springs that flow into different spots along Henry’s Fork allow the addition of colder water to parts of the river.
Secondly, these temperature changes can impact the river we know and love, but not necessarily drastically. When it comes to fish, trout are adaptable to a range of temperatures and can travel to cooler parts of the river on hot days. Hunter and I saw this a lot at Blue Springs Creek (one of our tributary temperature monitoring sites) as we went out in the field this summer. As for aquatic insects, we may witness a change in behavior, rather than population. We know from Henry’s Fork Foundation’s yearly aquatic insect nymph sampling that there are plenty of aquatic insect nymphs in the river, and the river is healthy in that regard, but why are anglers not seeing the hatches they had become accustomed to? With warmer temperatures, aquatic insects may grow, hatch, and emerge faster than expected.
Lastly, I think it is so important to mention that there are several ways to get involved in the upkeep and protection of Henry’s Fork, and that can mean helping with river cleanups, putting plants in places to protect cool water on the river, and supporting the Henry’s Fork Foundation in general! These warmer temperatures aren’t a reason to fret, they are a reason to get outside!
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On a sentimental note, with this blog post comes the end of my summer at Henry’s Fork Foundation, and it is hard to put into words the impact that this experience has had on me. I got to explore the great and utterly gorgeous state of Idaho, I met countless amazing people, and I learned just so, so much. I give my utmost gratitude to the people at Henry’s Fork Foundation, the Washington and Lee interns before me who inspired me to get out here my freshman year, and, of course, anyone who made me a milkshake this summer.
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