I have archived the June 2025 water level chart (above, and at left). After 3 months of more than average rainfall, it looked like precipitation in June was going to fall well short of normal with nearly three dry weeks with only occasional smidgens of rain falling. Then two days before the end of the month we received a whopping 1.56 inch deluge, most of it in just the last few hours. This and a wee bit more rain the following day brought us to 3.31 inches for the month, only 0.42 inches short of the June average 3.73 inches. We’ll call it good. The dry conditions for most of the month resulted in a gradual decline in the lake level with roughly 2/3 of the water loss due to evaporation and  only about 1/3 of it resulting from leaks. This is normal during dry summer weather.

Evaporation

Measuring lake water evaporation is a bit of a guessing game. Air temperature, water temperature, wind velocity, barometric pressure, and relative humidity (and probably a few more things I’m forgetting just now) are all factors in how fast or slow evaporation takes place, and coming up with a formula that spits out anything like a reasonable answer is not easy! We take a relatively simple approach to the problem, we really only want to know how much of a drop lake level is attributable to evaporation. That makes it easier: we start first by calculating outflows (including an estimate of leakage) and then calculating how much the lake level should drop after losing that much water and comparing that with how much the lake actually fell. If outflows should drop the lake 0.01 feet 24 hours but the lake actually dropped 0.03 feet in that time, then it is reasonable to assume the difference (0.02 feet) was lost through evaporation. It isn’t exact, but it’s close enough. You’ll find this another other fascinating data on our Dam Operation Log.

Lake water quality is improving thanks in part to the dry weather in June. Heavy rain in March, April, and May washed a lot of sediment and other nutrients into the lake resulting in a mild infestation of blue green algae and a transparency reading of 3.19 meters (10.5 feet) on May 18th. Most people probably didn’t even notice the algae die off at the end of May (picture at left). Thankfully it was pretty mild and short lived. Kelsie French and I conducted our 4th water quality monitoring session yesterday and found transparency greatly improved with secchi disk readings between 3.85 and 4.0 meters. See our Clary Lake water quality data page for more information.

Summer is here folks! Get out and enjoy Clary Lake!

I have archived the May 2025 water level chart (above, and at left). For the third month in a row we’ve received over 5 inches of rain with May having received just shy of 6 inches, making this one very wet spring! In fact, it has rained every weekend for the past 3 months! As of the end of May we’ve received a total of 19.84 inches of precipitation or 2.69 inches more than average for this date, and even more impressive statistic given precipitation in January and February were well below average. 

With all this rain you’d expect the lake level to have remained high, and you’d be right: the lake has been gently overtopping the dam all month. Also with all this rain you might expect some sediment-polluted runoff to have entered the lake resulting in moderate early season algae growth, and you’d be right again. Sure enough, Kelsie French and I started our Water Quality Monitoring for 2025 on Sunday, May 18th and the water was distinctly murky. We obtained a secchi disk reading of only 3.19 meters indicating some early season algae growth. As blooms go, 3 meters is really pretty mild (the State doesn’t consider your lake is blooming until transparency drops below 2 meters) and usually blooms this early in the season are short-lived. The algae quickly consumes the available nutrients and then dies off. In deed, only nine days later I spotted the telltale green scum on the lake surface, evidence of the cyanobacteria die off (picture above). On our second trip out to the deep hole on Friday May 30th, our secchi disk reading was 3.87 meters indicating the water was already clearing up. You can see where these first 2 secchi disk readings fall on the chart at left.

Assuming runoff slows down as the summer progresses, we can look forward to improving transparency later this summer.

I have archived the April 2025 water level chart (above, and at left). The drought conditions in January and February finally gave way to increased precipitation in March and that wet trend continued into April. We received 5.02 inches of precipitation more or less evenly spread out over the month, 1.20 inches more than average. This kept the lake level hovering between the top of the dam and the high water mark for pretty much the entire month. It did drop below the top of the dam briefly near the end of the month but 2 inches of rain on the 26th and 27th brought it right back up again. We ended the month with a lake level not too far from where is was at the start of the month. Our mandate from the DEP per our water level order is to fill the Lake to it’s “full capacity” after ice out, and we’ve done that. We’ll see where it goes from here! Continue reading →

I have archived the March 2025 water level chart (above, and at left). The drought conditions in January and February finally gave way to increased precipitation in March which made up some, but not all of the precipitation shortfall so far this winter. All told we received 5.17 inches of water in March, 1.40 inches more than normal bringing us to 8.80 inches for the year or 87% of normal. The lack of precipitation this winter has resulted in lowered ground water supplies leading the Maine Drought Monitor to calling us “Abnormally Dry,” a somewhat unusual condition for this time of year. We took advantage of the increased precipitation in March to raise the lake level by gradually adding stoplogs to the weir. We started the month with the lake at -1.35 feet below the HWM, briefly peaked at 0.3 feet ABOVE the High Water Mark, and ended at -0.09 feet with a little water flowing over the top of the dam. The gate is currently open 1/2 a foot. Continue reading →