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Good water year equals trout growth

Judy Van Put
Posted 10/5/21

Without a doubt, this has been one of the wettest summers in recent memory – as evidenced by the relatively poor vegetable and flower gardens that we and many of our friends have reported. We …

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Good water year equals trout growth


Without a doubt, this has been one of the wettest summers in recent memory – as evidenced by the relatively poor vegetable and flower gardens that we and many of our friends have reported. We have certainly received a lot of rain this year, with area rivers and streams registered above the average flow for most of the summer and fall. This is quite a contrast from 2019 and 2020, when more often than not the rivers were low, even being described as ‘bony’ on occasion. However, although 2021 has not been a great year for raising flowers and vegetables, it seems that it has been a good year for growing trout.

On Sunday afternoon, October 3, the Beaverkill at Cooks Falls was flowing at 477 cubic feet per second, which is well above the (median) average flow on this date of 159 cfs over 108 years of record-keeping. Water temperatures have ranged from a low of 51 degrees last Friday to a high of 58 degrees Fahrenheit, with the cooler nights helping to maintain these favorable conditions.

The NYC Reservoir system is also above the historic average capacity of 76.7% for this time of year. As of October 1, the total storage in all reservoirs was a whopping 94.2% capacity! This comes as a result of the precipitation for July, August and September being well above average: the September precipitation was 6.72 inches compared to the historical average of 4.62 inches; August was 5.26 inches as compared to the historical average of 4.29 inches; and in July we received more than twice the average amount of precipitation, 9.02 inches as compared to the 4.37-inch historical average.

DEC biologists consider this to be a “good water year.” A water year, also called a hydrological year, is the 12-month period from October 1st through September 30th for which total precipitation is measured. It differs from the calendar year because part of the precipitation that falls during winter and late autumn is typically snow that does not drain until the following spring/summer snowmelt. The average precipitation is based upon data from the past 50 years.

During such a “good water year” trout will thrive, as they are dependent on an abundance of clear, cold water, and are vulnerable to warming temperatures. As cold-water habitats warm, rising temperatures will have negative impacts on their life cycle phases—from eggs to juveniles to adults. Being cold-blooded creatures, their body temperature is largely regulated by the weather, and their ability to catch and process food changes with the seasonal variations in water temperature. The trout’s temperature tolerance is tied to more than just comfort, as colder water holds the greatest amount of oxygen they require. When the water warms, the dissolved oxygen begins to dissipate, causing the trout to feel stressed, and most will attempt to move to more comfortable water. In the case of wild fish, they will automatically move up to the headwaters. In addition to affecting the trout, water temperature also impacts the prey species that trout feed upon. But with an abundance of water such as we’ve experienced this year, the trout were able to survive and as long as food was available, concentrate their energy into growing without the added stress of having to move into cooler areas. It is generally accepted that the best growing temperatures for trout are from the mid-50s to about 68 degrees Fahrenheit. In 2021 we experienced less days where water temperatures were much above that ideal, and overall, it’s safe to conclude that the fish were not in stress this year.

2021 should also prove to be a good spawning year, as with the streams and tributaries at an above-average level, adult spawning fish should have a relatively easy migration and reach their spawning grounds in good numbers. During some years there is an accumulation of gravel and other debris at the mouths of streams and spawning tributaries, as well as culverts that become difficult to pass through, but this year those accumulations should have been carried away, thus enabling the trout to travel all the way up into the spawning tributaries where the cool water of the tributary springs average about 40 degrees; which is favorable to spawning fish.

So, thanks to this rainy summer and autumn weather and “good water year,” trout fishers have had some great fishing trips and are able to share their stories with others who are also reporting catching large fish, and can anticipate a number of large trout that will winter over into next year.


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