Water Temperature

 Temperature Profiles by Season at Shu Swamp and Beaver Lake

Hobo temperature data loggers have been in place at seven sites since May 2012. The temperature (Co) is recorded at 30 min intervals. The above graphs show the distribution of temperatures by season at the six sites. For brook trout, environmental temperatures between 5o C (41o F) and 20o C (68o F) are considered adequate and temperatures between 14o C (57o F) and 19o C (66o F) are preferred. Temperatures above 29o C (84o F) are lethal. Temperatures outside the adequate range are likely to cause some degree of reversible stress. In the graphs, look for colors in the orange range to indicate some possibility of high temperature stress, while red is lethal.

Clearly Beaver Lake is NOT the place to be in late summer through early fall. Temperatures in the summer exceed the lethal level for significant periods of time. This isn’t surprising when you consider its high surface area and shallow depth. None of the data loggers in Shu Swamp had temperatures above 29o C. The next worst temperature profile is near Frost Mill Dam (“Beaver Brook upstream”). In the summer, temperatures haven’t reached the lethal level but they are definitely in the stressful range. Of course this section of Beaver Brook is getting most of its water from Lower Francis Pond, where a good deal of solar heating occurs. As water in Beaver Brook moves downstream it is cooled by shade, input from the three branches (notice how temperatures stay cool in the branches all year), and cold water seeps. It warms up a bit well downstream and in the shallow pond where the railroad bridge is. Both the downstream section and the pond probably have stressful conditions for part of the summer.

The same trends hold true at the other extreme. Beaver Lake falls below 5o C much of the winter. In Shu Swamp temperatures below 5o C are experienced about 1/2 of the winter.

Download Temperature Data

Each temperature symbol represents the location of a temperature data logger. Click on the symbol and click on the link in the popup box to download an excel file containing the latest data for that logger.

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Data last updated May 26, 2014.