And so we come to the end of another year. I have archived the December 2025 water level chart (above, and at left) and also updated the 2025 Water Level Charts gallery with all the relevant 2025 charts for Clary Lake (and probably a few irrelevant ones as well) showing the year in numbers: lake level, transparency, dissolved oxygen, temperature, rainfall, flushing rate and retention time, etc. I do hope you’ll take some time to review the charts.

We received 41.21 inches of precipitation for the year, 2.85 inches short of the average annual rainfall of 44.06 inches. 2.85 inches isn’t a  huge shortfall but because of the timing of the precipitation we did receive (most of it fell in March, April, and May), we still ended the year in Severe Drought.

I’ll leave you with the 2025 water level chart which dramatically shows the falling water level and rainfall amounts. This year I added the secchi disk readings (in meters, right hand scale) that we recorded last season; you can see that as the lake level fell, so did lake transparency, ending up in late September just under 2 meters- officially an algal bloom:

November 2025

I have archived the November 2025 water level chart (above, and at left). At the end of October we were in Extreme Drought, While we’ve seen some relief in this area, at the end of November we’re still in Severe Drought and the lake level during the month reflected that condition, ending the month at -1.74 inches, not even 2 inches higher than it was at the start of the  month. As of November 30th we’re 5.64 inches shy of normal precipitation which is a significant shortfall though it doesn’t sound like a lot.

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 →

November 2024

I have archived the November 2024 water level chart (above, and at left). The dry weather we experienced in September and October continued with a vengeance in November, normally our wettest month with average monthly rainfall of 4.58 inches. We  did end up receiving 2.81 inches or 61% of normal, almost all of it falling at the end of the month. Thanks to excess rain back in March, June, and August, we’re still almost 5 inches ahead for the year but even so, we remain firmly in Moderate Drought going into December. According to the USGS,  groundwater levels in this area are quite low, even for this time of year. Continue reading →

September 2024

I have archived the September 2024 water level chart (above, and at left). September is often when fall rains start to pick up but that didn’t happen this year. September was dry. Normal rainfall for the month is 3.84 inches but this year we received less than half that amount, just 1.75 inches with most of it coming in one storm on the 26th. Still, despite drought conditions in September, for the year with 42.32 inches, we’re still well above normal rainfall for this date. Prior to the rain storm late last week, the US Drought Monitor showed our area to be “Abnormally dry” and I don’t think the rainfall fully alleviated that condition. Still, there’s a good deal of ground water thanks to all the excess rainfall we’ve received this season. Continue reading →

Some of you might have noticed a little green algae collecting on your shoreline over the last couple of days. This is dead cyanobacteria that floats to the surface and gets pushed around by a gentle breeze. It dissipates fairly quickly so it’s easy to miss, it is what is often referred to as an “ephemeral algal bloom”. As the lake cools off and the thermocline breaks down, Phosphorus from the bottom of the lake starts to mix with the epilimnion (upper water layer) and it stimulates some algae growth. This is fairly normal this time of year for a mesotrophic lake like Clary. We’ve seen much worse. These events are usually so ephemeral that they often go unnoticed, especially with fewer people on or near the water at this time of year. I think we’ll avoid a severe bloom this fall thanks the low Phosphorus levels in the lake this summer: our August 11th water sample for Total Phosphorus testing came back at a paltry 11 µg/L (micrograms per liter) which is a record low value for Clary Lake going back to 1975. We’ll be taking one final water sample for TP testing next weekend.

Minor algal blooms like this do not pose a health risk for humans or animals.

August 2024

I have archived the August 2024 water level chart (above, and at left). This is typically the time of year when drought takes over and evaporation controls the lake level but we actually received enough rain in August to mostly offset water loss from evaporation and leakage. We started the month with the lake level down -0.54 feet and ended the month down only -0.70 feet for a net loss of 0.16 feet or 1.9 inches. What’s more, the average rainfall from any given storm was only a quarter of an inch so we didn’t have any large, fast storms which would have washed sediment into the lake. The upside is it helped our water quality remain high while still getting enough rain to keep things green but the downside is it did seem like it rained all month. In fact, we got some amount of rain on 19 of the 31 days of the month so it might have seemed like we got more rain than we did. As for rainfall, we ended the month having received 4.92 inches of rain, only 1.59 inches more than normal but for the year, we’re at a whopping 40.56 inches of precipitation or fully 12.81 inches MORE water than is normal for the end of August. Continue reading →

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 →