Why is the Farmington River so warm? Or: when tailwaters don’t work

I’ve been getting a lot of questions about Farmington River water temps. The basic outline is, “I thought the Farmington is a tailwater. Why is the river so warm?” The answer is pretty simple.

In case you don’t know, a tailwater is a river with a dam release. The flow of the Farmington River West Branch is controlled by water that comes out of gates from the base of a reservoir dam (Colebrook Reservoir and Hogback Dam). If you’ve ever gone swimming in a pond or lake, you know that the water is warmer near the surface and colder near the bottom. This is called thermal stratification. In a larger reservoir, you have three different thermal layers: the epilimnion (the warmer upper layer; the metalimnion (or thermocline, the middle layer); and the hypolimnion, the coldest bottom layer. But I said this was simple, and there I go throwing all kinds of hifalutin hydro-science terms at you.

Ideally, there’s a happy medium of bottom release flows on a tailwater: cold water is never released in amounts that cannot be quickly replenished. But there are two situations that screw everything up.

The first is severe drought. Water that flows into the Colebrook Reservoir is reduced to a warm trickle. The volume of the reservoir shrinks from evaporation. The temperature of the water rises, especially if it’s hot, which decreases thermal stratification. As a result, what comes out of the bottom of the dam is warmer than ideal. (By agreement with the CT DEEP, the MDC must maintain a minimum release of 50cfs.) Because the flow is so low, water downstream warms quickly, trout get stressed, and it’s a bad scene all around. (This was the case in 2016. It was so bad that the DEEP took the unprecedented step of declaring thermal refuges on the Farmington.)

But that’s not what happened this year. This year, we had too much water. All that rainfall in July meant that the MDC needed to bleed water, and lots of it — so much, in fact, that it wiped out any meaningful thermal stratification in the reservoir. They’re still running such a high volume of water that there’s no chance for the stratification to re-establish — at least not in the heat of August. So that’s why at noon today the water was coming out of the dam at a very trout-unfriendly 69 degrees.

Eventually, it will get better. But right now, the best thing you can do for Farmington River trout is play the waiting game.

Taken this winter when the water was very, very, cold. Hang in there, buddy!

Bad times in New Hartford

In case you didn’t hear, the historic New Hartford House building was gutted by fire earlier this week. The three-alarm blaze happened Monday night/Tuesday morning. New Hartford House was the large, stately building with the clock tower in the center of town. Please send your thoughts and prayers to those who lost their homes and businesses, and also to the first responders who were injured fighting the blaze. You can read more about the fire in this story from the Courant.

Meanwhile, you shouldn’t be fishing the Farmington right now. Here’s the Riverton gauge at noon — and the heat wave has only just begun.

We are certainly going to lose some trout (nature will find a way for others). If you must go fishing, pond bluegills are a blast on a small stream rod and an Elk Hair caddis. Bass, striped or largemouth or smallmouth, are other viable options right now. But please, give these stressed fish a break.

Upcoming articles for Field & Stream, and warm water caution

Good Monday afternoon! A bit of a late start for me today as I was out chasing fish last night and didn’t get to bed until the wee hours. August is traditionally viewed as a prime vay-cay month, but here at currentseams we are busy-busy-busy. First up: I have three new articles in the pipeline for Field & Stream Online. In no particular order (these are just working titles): Tactics and Strategies for Fishing High and Low Water; Seven Best Flies for Smallmouth Bass; Small Stream Fly Fishing 101. As I have not yet begun to write, I have no pub date other than ASAP. I’ll get that information out to you when I know it. In the meantime, it’s not all chained-to-my-writer’s-desk energy. I still have fishing — lots of fishing — to do.

To the Farmington River. August is typically an active guide month for me, but I’ve had to make the difficult decision to suspend lessons on the Farmington until further notice. The issue is one of elevated water temperatures, which begets limited time and access. This graph of the water temp out of the gate at Hogback says it all:

A short week ago, you had just a shade over 64 degrees out of the gate, with a spike of a still trout-friendly 66. Today we’re already over 68 degrees (keep in mind that this is Riverton) and it’s not even a scorcher kind of day. With a heat wave projected for this week, it doesn’t take a degree in environmental science to recon that the trout will be experiencing stressful conditions. So please: give the trout a break. Protect the resource. It sucks, but it’s the right thing to do. And, as with gravity, what goes up must come down.