Yesterday August 11th, during our regularly scheduled water quality monitoring session I obtained a secchi disk reading of 5.45 meters (17.88 feet) which is a new transparency record for Clary Lake. The previous record was 5.30 meters observed on September 14, 1994. You can see today’s data point sitting all by it’s lonesome, high on the right side of the above chart, and noticeably higher than any other dot on the chart. Kelsie French who normally accompanies me wasn’t able to join me today so my wife Margaret came out to help. She tried her hand at taking a secchi disk reading and got 5.25 meters, only 4 inches shallower than my reading.

We also took a 4 meter core water sample for Total Phosphorus testing, our third TP test of the summer so far, We’ll take another one in mid-September. Not surprisingly given our clear water this summer, the first 2 TP tests came back at 0.012 mg/L which is exceptionally low for Clary Lake.

Our water quality data is available on our Clary Lake Water Monitoring Data page.

I have archived the July 2024 water level chart (above, and at left). July was a hot and seemingly dry month, though in fact we received the average amount of precipitation for July of 3.53 inches. Most of the rain fell in the first half of the month and as a result, the lake level remained at or slightly above the top of the dam until the 17th when drier weather settled in for the rest of the month. We ended the month down -0.54 feet below the HWM, having lost only  0.37 feet of water, with evaporation accounting for about 3/4 of that loss. Still, even with only average rainfall for July, we’re at 140% of annual precipitation for this date, thanks to above average rainfall in March, April, and June. Continue reading →

Clary’s water quality this summer is in a word, awesome. I’m sure  any of you who’ve been swimming will agree! The clarity so far this summer is measurably better than we’ve seen in a long time. Last weekend on July 14th Kelsie French and I went out for our biweekly water quality monitoring session at the “deep hole” and we both had secchi disk readings of 4.81 meters (15.77 feet). This is the deepest secchi disk reading we’ve recorded since a 4.88 meter (16.00 feet) reading back in May 2003 (see chart at left). There have been less than 10 secchi disk readings as good or better than today’s, going back to 1975, and none in the last 20 years. Extraordinary. Today’s secchi disk reading was actually the 5th consecutive reading deeper than 4 meters, also extraordinary. We haven’t had a stretch of clear summer water like this in Clary Lake for a long time. Continue reading →

I have archived the June 2024 water level chart (above, and at left). June was a dry month, until it wasn’t. Things were getting pretty dry by the 19th of the month, having received only 1.15 inches of rain up to that point. Then the sky opened up! Over the next 10 days we received an additional 6.90 inches or rain bringing us to 8.05 inches for the month, making June the second rainiest month of the year so far, only inch and a half behind March (see chart below). This brings us to 32.11 inches for the year, close to a foot more than normal. The lake level, which had been gently falling for the first 20 days of the month, spiked at 0.15 feet ABOVE the HWM on June 25th, flooding a few docks around the lake and making many others perilously close to flooding- including mine. Only some hasty gate adjustments kept the lake from getting even higher. It’s not that we were caught napping, the problem was that the three biggest rain events, while anticipated, far exceeded the forecast amount of rain.

Outflows from Clary Lake in 2024 (chart at left) remain the highest of the previous 5 years, though 2023 flows are not far behind. To date, 1.6 lake volumes of water have passed through the lake and headed downstream to the Sheepscot River. Keep in mind that the published ANNUAL flushing rate for Clary Lake is only 1.8 lake volumes and with the year only about half over, we’re almost there already. It is pretty clear that we’re going to exceed that published figure this year, perhaps by a lot. The impact of all this flushing on our lake water quality still remains to be seen. There are some indications and some historical evidence to suggest that a high flushing rate good thing. Normally however, high outflows imply high inflows which usually bring sediment, Phosphorus, and other nutrients into the lake, feeding algae growth. So far this year however, lake transparency has remained high: our last secchi disk reading on June 16th was 4.73 meters (15.5 feet) which is very good for early summer, and much better than this time last year. It is however still early in the summer season but for now, it’s looking good.

Kelsie French and I resumed our water quality monitoring efforts for 2024 on Sunday May 5th, a little earlier than in recent years. The lake is still largely homogenous with a surface temperature of 13.3°C (55.9°F) and 11.2°C at 8 meters. Surface DO was 11.3 mg/L and 8.4 mg/L at 8 meters. The Secchi disk reading was 3.55 meters (11.6 feet) which I guess is about normal for this time of year, but nothing to write home about. You can see where it lands on the chart at left (the sole data point, far to the right, in the 2024 column right below the red trendline). You can see a subset of water quality data including transparency going back to 2001 on our Clary Lake Water Quality Monitoring Data page. Today the water was kind of murky. Despite being early in the season, there’s already phytoplankton, primarily diatoms, populating the lake. As the water warms up, the diatoms will mostly die off to be replaced by green and blue-green algae later in the season. It’s really the blue-green algae (Cyanobacteria) that we’re worried about. Blue-green algae is mostly a late summer and fall phenomena. Continue reading →

I have archived the April 2024 water level chart (above, and at left). April was another wet month, though not nearly as wet as March had been: we received 4.62 inches of rain, 3/4 of an inch more than the 3.87 inches we’ve received in a “normal” year, whatever that means. Most of that rain fell by the 12th of the month, only a little over a half inch fell during the rest of the month. This allowed the ground was to dry out a bit. For the year we’re at 20.58 inches of precipitation, a little more than 7 inches above average for this date. This bodes well for ground water supplies later this summer. All this water has kept the lake level generally higher than we like: March actually ended with the lake level 0.31 feet above the High Water Mark or fully 6 inches ABOVE the lowest spot on the top of the dam. When the lake is that high, there is a real risk of shoreline erosion in areas around the lake that are not protected by a rocky shoreline. However, managing the dam to maintain a specific lake level is a real challenge and the response to a change in gate opening or weir height can be maddeningly slow. It’s too easy to over shoot the mark, or fall short of it. Therefore, we try to avoid large gate and weir adjustments and take some time to bring the lake level up or down where we want it. Continue reading →