As we move into the dog days of summer, most times freshwater fly anglers experience lower flows and hotter water, which can present unique challenges for anglers, as well as the fish they’re looking for. As water levels drop and temperatures rise, fish behavior changes, making adapting your tactics and approach crucial. Additionally, when water gets too hot, popular game fish, such as trout, have a much harder time recovering from a fight, and mortality rates, even after safe handling, can skyrocket. In this article, we partnered with onWater Fish, to explore strategies for successfully fly fishing during lower flows and target alternatives for trout, when water temperatures exceed 68 degrees Fahrenheit.
Understanding Low Flows and Warm Water Conditions
What Happens When Water Temps Reach Above 68 Degrees
Strategies for Fly Fishing Low Flows
Strategies To Stay Away From Hot Water & When To Stop Fishing
Check Out Other Species To Target
Understanding Low Flows and Warm Water Conditions
Low flows occur when rivers, streams, or creeks experience reduced water levels, often due to drought, irrigation demands, or seasonal fluctuations. Most times in the mountain west we see this happen with freestone rivers (rivers fed by snowmelt and smaller tributaries). These conditions can concentrate fish in smaller areas and make them more wary and selective when feeding. On the other hand, warm water conditions can affect fish metabolism and oxygen levels, potentially reducing their feeding activity and putting them under stress. Typically, in mid to late summer, some water temps on freestone rivers will breach 68 degrees, where if these fish are caught they might have a tough time swimming away.
What Happens To Trout When Water Temps Reach Above 68 Degrees
The plain and simple: When water temps reach over 68 degrees, oxygen levels decrease. With less oxygen in the water, trout are less able to recover their energy after a fight. Trout, at this temperature, will still eat your flies; however, they may not revive after they’ve made it into your net. Even when a trout is handled with care and released gently back into the water, oftentimes, just the stress of the fight combined with a lack of oxygen necessary for recovery can lead to the fish dying a short time after release.
- Increased Stress: Warm water conditions put additional stress on trout. The combination of elevated water temperature and the physical stress of being caught can lead to exhaustion and reduced energy reserves. Trout may struggle to recover from the stress of being hooked and fought, making them more susceptible to injury or disease.
- Reduced Oxygen Levels: Warmer water holds less dissolved oxygen than colder water. As a result, trout may struggle to obtain sufficient oxygen to meet their metabolic needs. This can weaken them and make them more vulnerable to predation, infections, and other stressors.
- Decreased Feeding Activity: Trout’s metabolism slows down in warmer water, leading to a decrease in their appetite. They become less inclined to actively feed, making it more challenging to entice them with flies or other bait.
- Limited Habitat Options: Trout seek out areas with cooler water when faced with warm conditions. In rivers and streams, they may concentrate in deeper pools, undercuts, areas with colder inflows, or near channels that hold more whitewater or oxygen. This can result in increased competition for these limited habitats, which may further stress the fish and affect their behavior.
- Increased Susceptibility to Disease: Warm water can promote the growth of harmful bacteria, parasites, and fungi, which can negatively impact trout health. When caught and handled in warm water, trout may suffer from open wounds or damaged fins, providing entry points for infections and diseases.
Here are some helpful tips to keep in mind if you are planning on trout fishing in warmer conditions:
Know before you go: With ambient temps currently at the highest they’ve been all year in most popular trout fisheries – it’s important to know conditions/ temps before you go. In the same way you’d scan a forecast for rain, or get ahold of a weather report to see whether it’s a pants or shorts day, it’s important to check your fisheries conditions for temps and flows as well.
A great resource for this the My Waters feature on the onWater Fish App. onWater Fish allows you to access instant insights on your favorite rivers and their conditions when you set your ideal water temps and streamflows in the app. That way, you can make an “at a glance decision” on what, where, and when to fish (so you don’t even have to think about going golfing).
Additionally, before your outing, make sure to grab a stream-side thermometer or pick one up at your local fly shop. The best practice in low flows is to take a water temp with a stream-side thermometer to double-check where you’re at.
If you’re in a location that is below 68 degrees, approach the water cautiously, keeping a low profile and avoiding sudden movements. Stay back from the bank and use longer casts to minimize the chances of disturbing the fish.
Insect activity becomes even more critical when fishing in lower flows. Spend time observing the water and the insects present. Match your fly selection to the prevalent hatches and focus on imitating the natural food sources available to the fish. if you’re unsure, always be sure to stop by your local fly shop for fishing tips, techniques, and advice from local guides. Never fish for trout in water above 68 degrees!
Strategies for Fly Fishing Low Flows
If you are planning on fishing for trout in water around or above 65 degrees Fahrenheit, check out these tips for safe catch and release.
- Rope Up: Rope up with heavier tippet to land the fish quicker. Keep them wet and skip the pictures to minimize their time out of the water.
- Check USGS: Check USGS to get real-time data on flows, temperatures, cubic feet per second, turbidity, pH levels, and more.
- Keep ’em wet: If you’ve gotten to this point and the water is breaching 65 degrees, keep the fish wet and practice catch-and-release.
When it comes to photography, be sure to keep the fish in the water even when the water temperatures are below 68 degrees. Most times in the summer months, fish can be stressed due to lower oxygen levels during the hottest months of the year. If you’re looking for a grip and grin, get your hands wet and think twice before taking that fish out of the water.
Strategies To Stay Away From Hot Water & When To Stop Fishing:
One thing to examine before fishing is to determine the right area to fish, and check the flows, turbidity, and temperatures before embarking on an angling journey. Fish early or late in the day (before water temps exceed 68 degrees, and when temps drop below 68 degrees). When water temperatures rise, fish are more active during cooler parts of the day. Plan your fishing trips for early mornings or late evenings. This way, you can take advantage of the fish’s increased activity levels and make sure they can be released safely.
Be sure to choose the right locations. Look for areas where the water is cooler, such as shaded sections, deep pools, or areas with natural springs or inflows. These areas often provide refuge for fish during warmer periods. Additionally, larger bodies of water, such as reservoirs or tailwaters, may have cooler water releases from deeper depths, attracting fish, and would be a better option than fishing sections that have hot water.
Practice Catch-and-Release: Warm water conditions put additional stress on fish, and their survival rate after being caught decreases. Consider practicing catch-and-release to minimize the impact on fish populations and their overall health during these challenging conditions and be sure to Keep Fish Wet.
Check Out Other Species To Target
The best way to keep trout safe when fishing in high water temps is to simply not fish for them at all. Now, that doesn’t mean breaking down the rod for the Summer months – it’s actually the opposite. It’s an opportunity to explore and expand your horizons as a fly angler.
A helpful tool for if you want to find a new species to fish for, or a new place to catch your favorite species, is onWater’s fish species map layer shows you known locations of over 100 fish species, allowing you to get away from the crowds and explore something new.
Even if you’re an experienced trout angler, chances are there are other species in proximity to where you live, and are just as fun to catch on the fly. Fly fishing for most is about exploration, fishing new water, and learning about fish behavior, so why not try and target a new species? If trout fishing is not an option, consider fishing for carp or bass. These species are wildly fun to target and catch on the fly and can be “a whole other ball game” to most anglers. Be sure to check in with your local fly shop or check out the articles below to learn more about other freshwater species to target on the fly.
Graphic from Trout Unlimited. Get your stream-side thermometer by clicking HERE.
It’s such a smart thing to carry a thermometer and to check the water to make sure you’ll have an easier time fishing. Thank you so much for this tip!