By this time each year, in July and August, some of our trout streams are in perilous condition. High water temperatures along with low flows set up life-threatening conditions for trout populations. 

To see how some of the nation’s most famous trout rivers were faring, I did a little research. In Montana, for example, sections of the Big Hole, Gallatin, Madison, Bitterroot and Clark Fork Rivers—to mention a few—are under “Hoot Owl” regulations. That means any time water temperatures in those rivers reach 73 degrees Fahrenheit three days in a row, fishing is curtailed between 2 p.m. and midnight. That regulation prevents anglers from hooking and playing trout during conditions that are extremely stressful. 

Closer to home, the USGS gage at Cooks Falls, NY on the Beaver Kill recorded a flow of 138 cubic feet per second (CFS) with a water temperature of 80 degrees Fahrenheit, while the upper East Branch of the Delaware at Margaretville, NY showed a flow of 58 CFS and a water temperature of 78 degrees. Temperatures lethal to trout survival in both rivers. Those conditions were documented on July 14 of this year.

While the New York State DEC does close a section of the Beaver Kill River from the bridge at Horton, NY downstream to the first Route 17 overpass during July and August, the rest of that river and all other Catskill rivers remain open to fishing. No Hoot Owl regulations here, likely because unlike Montana, nighttime air temperatures do not drop enough to cool water temperatures significantly. 

Fortunately, most anglers who fish these rivers are astute enough that during July and August, they abandon the freestones; instead, they flock to the tailwaters.

In contrast, the tailwater downstream from Pepacton Reservoir flows cool, clear and clean behind our camp. The filaments of green algae, indicators of very cold water, wave gently in the current.

At some point later in the day, as the sun slides behind the mountain, mayflies will come. There will be a steady hatch of the various Baetis, or olives as they are commonly known, as the day progresses. On cool, cloudy days olives will hatch at any time. These diminutive mayflies will continue to emerge well into October, providing dry fly fishing for the hardy as the weather cools. 

Meanwhile, down river a few miles, where the water temperature warms up a bit, every morning around 9 a.m. there will be a hatch of tiny trico mayflies (Tricorythodes sp.) I’m told that these little flies hatch, molt from dun to spinner over the river, then return to egg lay all within a few hours. After the reproductive process is complete, dead and dying flies cover the water and offer about two hours of surface activity. If the wind does not blow; tricos are about; and you are a good caster, capable of fishing 7X with size 20 or 22 imitations, there is good sport to be had during these spinner falls. 

Years ago, I found these diminutive mayflies on the Madison River, just outside of Yellowstone Park, every morning around 11 a.m. But tricos appear about two hours later there than in the Catskills. Unfortunately, just about every time I found these flies in the air and on the water, with trout beginning to rise, the famous famous Montana wind would begin, ending the fishing.

During that same trip, I found a good hatch of trico duns emerging along the Henry’s Fork River in Idaho. I landed two very nice Henry’s Fork rainbows, using size 18 olive on 6x tippet, during that emergence and was very proud of myself!

Anglers who fish the East and West Branches of the Delaware should keep an eye out for changes in flow. The New York City DEP plans to close the Delaware Aqueduct in October to repair a leak that loses up to 35 million gallons of water per day. That aqueduct runs between Rondout Reservoir in Ulster County, under the Hudson River, and over to the West Branch Reservoir in Putnam County. The goal is to reduce the volume of water in the Pepacton and Cannonsville Reservoirs to about 70 percent by October. That will be undertaken to minimize flooding, since there will be no diversions of West Delaware water to New York City. To achieve that level of capacity, releases from both reservoirs might be higher than normal. 

During that shutdown, the DEP’s Catskill and Croton systems will make up the loss created by the Delaware System. 

Summer fly fishing, whether in the East or Rocky Mountain West, can be a mixed bag. In the East, major hatches are over, and with the exception of tailwaters, flows are low and temperatures high, making fishing difficult for both anglers and trout. In the West, hatches are beginning but lack of snowpack, along with higher air and water temperatures, are causing some rivers to be closed to fishing after 2 p.m. So regardless of where anglers plan to fish, it’s important to check flows, water temperatures and regulations before going forth, to see where the best fishing opportunities are to be found.