I have archived the April 2021 Water Level Chart (at left). The dearth of precipitation that has plagued us for much of last year and for the first three months of this year has continued into April with total monthly rainfall amounting to only 3.12 inches, a good deal of which we received on the last day of the month. This is well below the April average of 3.87 inches. Year to date we’re 3.5 inches below normal and we’re only a third of the way through the year. This does not bode well for ground water supplies this summer, even if precipitation returns to something like normal. The USDA has categorized this area of Maine as “Abnormally Dry” (see below) which is certainly an unusual condition for Springtime in the Northeast. Nationwide, drought conditions are much worse as this next graphic from the Maine Climate Office clearly shows:
While the lack of snow cover and spring runoff have resulted in abnormally low water levels in many Maine lakes this winter, we have managed to maintain both an acceptably high and under the circumstances, quite a stable water level in Clary so far this year and we hope to be able to continue to do so! You can see from the the water level chart the number of adjustments we made to the gate (the red dashed line) throughout the month to adjust the outflows. As a result of these adjustments we were able to keep the water level in April fluctuating within a fairly narrow range of a little over 2 inches, starting out the month at -0.19 feet and ending the month at -0.08 feet, thanks to the late month infusion of rain. Unlike the last two years, the water level this year has yet to reach the Normal High Water Mark elevation of 151.17 feet, though this last rain storm may push it that high. Nonetheless, we consider the lake to be filled to it’s full capacity when the water level is at (or slightly above) the top of the dam.
In last month’s March 2021 Water Level post, I wrote about Flushing Rate and Retention Time, what they are and how they can differ from year to year depending on precipitation. I also speculated on how they might relate to water quality. I continue to be fascinated by this subject. The difference in lake outflows between this year and last are significant: last year on April 29th the sum of 2020 lake outflows was a healthy 8994 acre feet. This year on the same date lake outflows are a paltry 3624 acre feet or about 40% LESS than last year’s value. That’s a HUGE difference! Similarly, the retention time last year on this date was 96 days while this year it is 237 days or about 40% MORE than last year (makes sense if you think about it). I will be very interested to see what effect this has on lake water quality. We will be resuming our Water Quality Monitoring activities within the next week.