Category Archives: Technical Lake Stuff

Fall 2023 Clary Lake Algal Bloom

While it doesn’t appear quite as severe as last fall (at least not yet), this fall’s cyanobacteria algal bloom is gathering steam. This is not wholly unexpected: our last lake transparency reading was only 2.7 meters (8.8 feet) and there was quite a bit of green algae in suspension (see 2023 Water Quality Monitoring Season Comes to a Close) so I’m not really surprised to see this. The picture at left was sent to me yesterday afternoon by Danny Bell. Quite a shot! Apparently the aquatic growth helped keep the algae from drifting off. I went down to my shoreline and found only a thin greenish sheen of algae on the surface- nothing to compare with what Danny was seeing. The blue-green bacteria dies and floats to the surface where it’s moved around by wind and currents and in some places you’ll see quite a bit of green and in others much less or even none. Last year the bloom continued into early December. Hopefully this one will burn itself out soon. I will be sending a sample into DEP for testing.

This picture was sent to my wife this morning by Fran Marsh who was understandably concerned.

Please send me your observations and pictures!

2023 Water Quality Monitoring Season Comes to a Close

On Friday afternoon, October 13th, Kelsie French and I wrapped up another season of water quality monitoring on Clary Lake. Started by my father Stuart Fergusson and David Hodsdon back in 1975, this marks the 48th year quality data data has been collected Clary Lake one of the longest monitored lakes in Maine. It’s not summer anymore and the last day on the lake is typically cold, raw, and windy. This one was no exception as the above picture of Kelsie French (getting an air temperature reading) suggests! The weather wasn’t near as bad as we’ve experienced before, not by a long shot. We do prefer days more like the picture at left, taken back in August.

We were a little late getting started this spring thanks to a bad cable on our YSI Pro 20 Dissolved Oxygen meter which we purchased new in 2013. The new cable cost $390 and didn’t arrive until early June. Consequently, our first data collection session on the lake wasn’t until June 11th. We usually like to start in late April or early May.

It isn’t simply cold weather that brings our water quality monitoring season to a close, it’s the fact the lake has “turned over” meaning the lake water is now thoroughly mixed from top to bottom. The lake basically goes into “rest” mode for the winter and most biologic activity winds down and becomes dormant for the winter. Soon the lake will freeze over (to learn more about that process, see this page on Ice Berms & Pressure Ridges). During Friday’s data collection session we observed surface dissolved oxygen and temperature readings of 8.5 mg/liter and 16.7°C (62°F) and near the bottom at 8 meters it was little different (8.4 mg/liter of dissolved oxygen and a temperature of 16.5° C). Once turnover happens in the fall, there is little reason to continue with water quality monitoring. The season is over. We’re still waiting on the results of our last Total Phosphorus test sample taken on September 22nd. I’ll post them on the Clary Lake Water Quality Monitoring data page when it arrives; I expect it will be higher than normal due to the fall turnover.

Transparency was the lowest we’ve seen it this year at only 2.70 meters (8.85 feet) with light obscuring particles of green algae quite evident in the water column. This was not surprising considering the fall turnover and the minor cyanobacteria bloom we’ve seen this fall. Compared to last year, what we’ve seen this fall is minor in deed.

While we stop measuring transparency and dissolved oxygen in the fall and winter, I will continue to monitor lake conductivity (chart at left) throughout the year. Conductivity is a reasonable proxy for lake productivity and as winter sets in, I expect conductivity will drop. As you can see on the chart at left, conductivity of water collected at the outlet (the blue line) peaked in mid-March with snowmelt runoff which undoubtedly included road salt, then dropped way down with the influx of heavy rainfall around the 1st of May. Since then it’s been gradually climbing indicating increasing lake productivity. Unlike in MY case, productivity in a lake environment is a bad thing! Interestingly, conductivity of a core sample of lake water has remained relatively stable throughout the year. The implication of this is that runoff entering the lake (and there was a lot of runoff…) doesn’t mix much with the full volume of water in the lake. This is not surprising when you think about it: the temperature stratification of the lake so evident in the summer clearly isn’t disrupted by rainfall and runoff as anyone who has gone swimming this summer is well aware. Mixing only occurs in early fall when the surface temp starts to drop. This mixing is evident by the relatively sharp rise in conductivity starting in early September.

September 2023 Water Level Chart Archived

September 2023

I have archived the September 2023 water level chart (above, and at left). The rain we’ve come to expect this Summer just didn’t materialize last month with only 2.80 inches of rain falling (73% of normal) or a full inch less than the 3.84 inches we would normally receive in September. An obvious impact has been the gradual drop in water level. That said, who didn’t like the extended stretch of warm dry weather in September? Of the first 9 months of 2023, only 3 months had less than the normal amount of precipitation: September (73% of normal), March (67% or normal) and February (52% of normal). The month with the highest precipitation was July, with 8.2 inches (232% of normal) followed closely by January with 7.19 inches (225% of normal). Despite shortfalls in those three months, at the end of September we were still 12.65″ ahead of normal. To better grasp how big a differential that is consider that our average annual rainfall is 44.06 inches, and we’re already there- we’ve already received more than that. Even if we were to receive NO MORE rain or snow for the REST OF THE YEAR, we’d still end up a hair above normal annual rainfall. That is how far above normal precipitation we are this year. The overall precipitation statistics for 2023 are impressive. You’ll find all kinds of data and charts on the Precipitation sheet of our Clary Lake Dam Operation Log. Continue reading →

Blue-Green Algae Finally Makes an Appearance

The lake has gone through its Fall Turnover meaning the temperature stratification that was a summertime feature of the lake has broken down and the lake water has mixed pretty much from top to bottom. The high winds from the remnants of Hurricane Lee last a week ago Saturday certainly helped with the mixing! Kelsie French and I were out doing our biweekly water quality monitoring last Friday and the water temperature at the surface (21.5°C) was only 2.5°C warmer than the water 8m (26ft) down. Two weeks ago the temperature difference from top to bottom was 7.8°C.

That turnover resulted in Phosphorus-rich water at the bottom of the lake mixing with the upper sunlit layers, giving a shot of nutrients to the cyanobacteria living there. A week later, they’re beginning to die off and float to the surface resulting in that telltale green scum on the water surface. The picture at left was sent to me by Jack Holland. Yesterday morning the green stuff was fairly evident over much of the lake surface (featured image, above), thanks to the lack of wind. It quickly dissipated when the wind picked up.

While no algae bloom is a good thing, as blooms go this one is pretty mild and it was expected. Hopefully it won’t get much worse. Last fall you may recall we experienced a much worse bloom, way more intense and widespread that went on for 3 months, extending all the way through November. It is likely all the rain we had this summer and the resulting flushing action that kept our water quality so high for so long.

August 2023 Water Level Chart Archived

August 2023

I have archived the August 2023 water level chart (above, and at left). The rain we’ve come to expect this summer did not disappoint! We received a total of 6.79 inches in a month when normal is more like 3.33 inches. For the month of August we’re at 204% of normal; we recorded some amount of rain on 18 of the 31 days of the month. All this rain puts us at 41.44 inches for the year, fully 13.69 inches more than normal for this date. We normally receive around 44 inches of rain in a whole year. Quite impressive! Not surprisingly, the lake level bebopped along merrily in a narrow range between the top of the dam and the High Water Mark. The average water level for the month was -0.17 feet below the HWM; it briefly dropped below the top of the dam for 5 days and rose above the HWM for a couple. For most of the month we kept the gate open half a foot to keep the lake from rising too high. We’ve never had that concern in August! Continue reading →

The Cyanobacteria in Clary Lake is Alive and Well

As nice as as our lake water has been this summer, and it has been nice, there is nonetheless cyanobacteria alive and well living in it. Runoff from all the rain we’ve received has washed sediment into the lake which is the primary source of phosphorus and phosphorus as you know by now is good for algae, bad for lakes. In the featured image above, taken by Jack Holland on the morning of August 10th, the telltale green scum comprised of dead blue-green algae is evident, but not terribly alarming compared to what we’ve seen before, even as recently as the first of June this year. After Jack sent me his picture, I went down to my shoreline and took the picture at left. The telltale green sheen is so faint and ephemeral as to be easily overlooked. But it’s there. If this is as bad as it gets this year we’ll be very lucky. Continue reading →

July 2023 Water Level Chart Archived

I have archived the July 2023 water level chart (above, and at left). The most notable thing about July was Holy Hannah did it rain! I thought we got a lot of rain in May with 5.40 inches and then we got even more rain in June, 5.51 inches in fact. I thought that was a lot of rain and then we got 8.2 inches of rain in July (normal is 3.54 inches). For the year we’re 10+ inches ahead of normal rainfall for this date. Things are a little soggy, to say the least! One unsurprising effect of all this rain is that the lake level this summer, with minor exceptions, has remained at or above the top of the dam for several months- quite different from the past few summers. We started July with the lake level at the top of the dam (-0.29′ below the HWM) and ended it even higher, almost 3 inches above the top of the dam (-0.05′ below the HWM). Continue reading →

24 July 2023: Midsummer Water Quality Update

Clary Lake Transparency

Kelsie French and I got out on the lake on Sunday for our biweekly water quality data collection and the results are worth sharing. We had a secchi disk reading (a measure of lake transparency) of 4.18 meters (13.71 feet) which while not unheard of, is actually quite good, especially this time of year, considering all the rain we’ve received this summer. Rain means runoff and runoff means sediment and sediment means Phosphorus and Phosphorus means algae… Two weeks ago it was 3.80 meters (12.46 feet). I didn’t expect to see it improve, but it did! You can see today’s reading on the far right just above the 4 meter line on the above chart. We’re definitely trending in the right direction! You can see a subset of the data we collect back to 2012 on our Clary Lake Water Monitoring Data page.

On the downside, dissolved oxygen (DO) was only 1.1 mg/l at 4 meters which is damned low for such a shallow depth; 2 weeks ago it was 5.4 mg/l at 4 meters and 2.5 mg/l at 5 meters. Today it rapidly fell off from 4 meters and at 7 meters and below we found NO oxygen at all. Under these severely anaerobic conditions, Phosphorus which is normally stored in bottom sediments can reenter the water column. As long as it stays near the bottom, it’s not a problem but in the fall when the lake turns over, this Phosphorus rich water will mix with the upper layers where algae live, and this can spur out of control algae growth. This is why most severe algae blooms occur in the fall. The bloom we had last fall was in part due to this phenomena. There were other extenuating circumstances.

We also took the first of 3 core water samples we’ll take this season for Phosphorus testing. We’ll take another in mid-August and a 3rd in mid-September.

Right now, the water quality in Clary Lake is very good but that may change this fall. Time will tell.

June 2023 Water Level Chart Archived

June 2023

I have archived the June 2023 water level chart (at left). If there is one thing that stands out about June 2023 is it was a wet month! We received some amount of rain on 21 of the 30 days of the month making this June the wettest June since 2019.

All told we received a total of 5.51 inches of rain in June, 1.77 inches more than the 3.73 inches which is normal for June. Despite February and March being well below average precipitation, at the end of June we’re fully 5.51 inches of rainfall ABOVE NORMAL for this date. Yes it’s been wet this year! Unlike April and May which both had rather large rain events, most of the rain events in June were small, averaging only 0.28″ per event. It’s like we were dribbled on for the whole month. Despite the almost constant rain, the lake level remained remarkably stable. With only slight adjustments of the outflows we were able to maintain the lake within a very narrow 3.8 inch range for the whole month, more or less centered around the top of the dam. We started the month at -0.28 feet (top of the dam) and ended the month at the same level. You’ll find ALL the relevant charts (water level, rainfall, flows, etc.) on our Current Clary Lake Water Level Charts page.

June started out with a short but intense die off of blue-green algae (picture at left), the growth of which was fed primarily by sediment-born Phosphorus introduced into the lake during the intense two-day rain event that took place on April 30th and May 1st. We received a total of 5 inches of rain in those 2 days resulting in the highest lake level we’ve ever recorded, and washed out driveways and roads all over the State. Untold tons of sediment washed into Clary Lake as a result of that one storm. One month later around the first of June, the cyanobacteria that had multiplied with the influx of food started to die and float to the surface where it was corralled by wind and currents along the south and west shore of Clary Lake. It is likely people on the northeast and east shore of the lake never noticed a thing. I collected a sample and dropped it off at the lab at DEP in Augusta. The sample was predominated by Dolichospermum flos-aquae, formerly Anabaena flos-aquae, a blue-green or cyanobacteria species. There was a lot of pine pollen in the sample as well. As the month progressed, the water column cleared considerably with secchi disk reading of 3.87 meters (12.7 feet) on June 23rd.

Kelsie French and I got an early start to our 2023 water quality monitoring season in late April with a trip out to the deep hole (picture at left) but the next time out erratic behavior with our YSI Pro 20 Dissolved Oxygen meter prevented data collection. It took some time, but by process of elimination we were finally able to determine that the cable on our 14 year old meter had failed. We ordered a new one for $380 + $10 shipping. They said it would be 7 weeks for delivery but it arrived after only 5 weeks. The new cable solved our problem and we were able resume data collection on June 11th. We’ll be out there every 2 weeks until mid-October. If you see us out there on a Friday afternoon in my red boat, anchored in the middle of the lake, stop by and say hello!

May 2023 Water Level Chart Archived

May 2023

I have archived the March 2023 water level chart (at left). We experienced two large rain events during the month with the result that there was water flowing over the top of the dam for the entire month. The first storm which started on April 30th and ended 3 days later kind of caught us by surprise. It went stationary, ultimately dumping 5 inches of rain on us and raising the lake level to +0.77 above the high water mark, the highest water level we’ve recorded since we purchased the dam back in the fall of 2018. The previous high was +0.58 feet back in April 2020. We thought that was pretty high! At its peak height on May 1st there was over a foot of water flowing over the dam. Then on the 22nd we received 2.65 inches of rain which raised the lake level to +0.28 feet above the high water mark. All told we received 5.40 inches of rain in May, 1.7 inches more than normal. Despite below average precipitation in February and March, for the year we’re 3.79 inches ahead of normal on this date. Continue reading →

April 2023 Water Level Chart Archived

April 2023

I have archived the March 2023 water level chart (at left). It looked like the dearth of precipitation that’s characterized February and March was going to continue through April, until the last day of the month when we received a whopping 2.52 inches of rain. The storm has continued into today, the first day of May with an additional 1.98 inches bringing the storm total to 4.64 inches! As of the end of April, accumulated precipitation for the year was 15.54 inches (it’s more than that today), fully 2.1 inches above normal for this date. At the time of this writing, this impressive overnight rainfall has raised the lake level to +0.85 (152.02 feet) which is the highest level we’ve recorded since we purchased the dam in the Fall of 2018. Peak runoff typically occurs 24 hours after the rain event, so I have not doubt that the lake level will rise higher. You’ll want to keep your eye on the Current Water Level Chart.

Here’s a picture I took this morning (at left) when the flows over the dam were around 268 cfs (cubic feet per second). Since then the lake has come up another 3 inches. I checked the level just before dark and it was up to +0.89 feet. The previous record water level since we purchased the dam in October 2018 was achieved on April 14, 2020 topped and out at +0.58 feet above the HWM. We’re over 3 inches above that already! Chester Chase owned the dam for nearly 50 years and his son Tim assures me that he’s seen it this high and higher during the years he spent growing up in Whitefield. Albert Boynton, who was born in the red house on the dam and whose family owned the dam back in the 1920s and early 1930s once told me that he remembers seeing the lake so high it was running over the road. That’s high!

The flow numbers for the April 30 storm are impressive! You can see that the daily outflows in acre-feet (43,560 cubic feet) of water so far this year (the blue line in the chart at left) have been pretty sedate so far this year until yesterday when they went through the roof with 605 acre-feet. Thanks to the storm, a wee bit more than 1 full lake volume of water (7,224 acre-feet) has flowed downstream so far this year. A lot of sediment washed into the lake during this storm, which is generally a bad thing. On the other hand, a lot of that water flowed right out again. It remains to be seen how this will impact our lake water quality this year.

I can write all day long about how high the water was, but there’s nothing quite like a video to convey an impression. I’ve already posted a video I took over at the dam yesterday morning. Here it is again:

7 April 2023: Spring Turnover and More!

I stopped at the boat launch the other day to check out the waves, and I was not disappointed! It’s windy days like this in the early Spring that churn up the lake water, mixing it together from top to bottom in a process known as Spring Turnover. The water column ends up with a uniform (and cold) temperature and the oxygen profile is similarly homogenous. Then throughout the course of the summer, the lake water stratifies with the surface warming up while remaining cold down below the thermocline. Then same turnover thing happens in the Fall, mixing the water once again. It’s an endless cycle: Spring turnover, Summer Stratification, and Fall turnover.

This video not only shows this turnover process taking place, you can also see the lines of white froth resulting from Langmuir Rotation.

March 2023 Water Level Chart Archived

March 2023

I have archived the March 2023 water level chart (at left). The precipitation deficit we saw in February continued into March with only about 2.5 inches of precipitation falling, well below the average for March of 3.77 inches. However, due to the excess precipitation we received in January, we’re still 1.5 inches ahead of normal for this date. March is when we start the process of gradually raising the lake level by adding stop logs to the weir, while at the same time trying to maintain minimum flows to sustain the downstream aquatic habitat. We could really use some extra water in March to help with this process, but it didn’t happen this year. Given the conflicting mandates in the Water Level Order i.e., raising the lake level to it’s full capacity by ice out AND maintaining minimum flows at the same time, it’s a rare year when we can accomplish both! Usually something has to give and raising the lake level to where it belongs in the spring is our number one priority. We did succeed in gradually raising the lake level about a foot over the course of the month to within 1/2 a foot of the HWM, by the end of the month. With close to a half inch of rain falling on this first day of April, we should be overtopping the dam shortly. No fooling! Continue reading →

February 2023 Water Level Chart Archived

February 2023

I have archived the February 2023 water level chart (at left). February did not continue the wet trend that start the new year. On the contrary. February has the smallest average monthly precipitation of only 2.61 inches but we failed to reach even that low bar, receiving only 1.35 of precipitation for the month, mostly in the form of snow. We started February fully 4 inches ahead of average precipitation, but we lost ground, ending the month only 2.74 inches above average. Despite this, because we received so much precipitation in January, outflows from Clary Lake remained extremely high for the entire month. How high you ask? In the first two months of 2022, total outflows from Clary Lake amounted to 2231 acre-feet of water. In the first two months of 2023, outflows amounted to 4667 acre-feet or more than TWICE as much water. In other words, in the first two months of 2023 more than half the full volume of the lake passed through Clary Lake. In fact, outflows in the first 2 months of 2023 far exceed outflows during the same two-month period for the last 5 years, back to 2019 with the greatest disparity occurring in 2021: Continue reading →

January 2023 Water Level Chart Archived

January 2023

I have archived the January 2023 water level chart (at left). By far the most impressive thing about January was how much snow and rain we got! Total precipitation including rain and (melted) snow was 7.19 inches of water which is more than twice the average precipitation for January of 3.19 inches. We’re starting off the year fully 4 inches above normal for this date. This will benefit ground water supplies this coming year. Even with all the snow and rainfall however, the water level was relatively stable though it was a little higher than we like to maintain it this time of year, due to all the inflows. January and February are usually pretty sedate months from a water level management perspective but this year we’ve had to open the gate a couple of times to let out more water just to keep the lake from overtopping the dam. There’s nothing wrong with overtopping, but this time of year it leads to ice formation which makes walking on the dam treacherous. We also like to keep the lake level lower in the winter to prevent ice damage to the shoreline. Mother nature however usually has her way. Continue reading →

December 2022 Water Level Chart Archived

December 2022

And that’s a wrap! I have archived the December water level chart (at left) bringing 2022 to a close. I guess the most impressive thing about December had to be the huge 24 hour lake level rise of 15.8″ from just 3″ of rain (and a little snow melt) on the day before Christmas for a runoff multiplier of over 5X. You can see excessive runoff this time of year because frozen ground means more rain runs off and less soaks into the ground. We’ve seen some big lake level responses to rainfall, but this is one of the biggest I can remember in a long time. Continue reading →

14 December 2022: Clary Lake ALMOST but NOT QUITE Iced Over

Yesterday afternoon Clary appeared to be fully ice covered and I was about to call it, but the bit of snow we received in the night has revealed some open water in the usual spot off the point at the end of Duncan Road, and a seam in the middle of the lake is evident as well, perhaps opened up due to the high wind this morning. In early winter there is often open water off Duncan Point (aka Young’s Point) due to the speed of the current there. We’ll see if the current ice cover will survive the warm and wet coastal storm due to blow through here this coming Friday into Saturday.

We have historical ice-in and ice-out data for Clary Lake going back to 2001. If anyone has data for years prior to 2001 I’d love to hear about it.

November 2022 Water Level Chart Archived

November 2022

I have archived the November water level chart (at left). Our plan at the beginning of the month had been to start dropping the lake to it’s early winter level around 14”-16” below the HWM. November is actually the month with the highest rainfall with an average of 4.58 inches but the first 10 days of the month were rain-free and we really didn’t know what to expect for the rest of the month so we didn’t take any drastic management actions, preferring to let the lake find it’s own happy level. Then the rains started first with a 1.85” rain event on the 11th followed by several more rain storms over the next 5 or 6 days which brought the lake level back up to the top of the dam by the 18th. On the 23rd we pulled the last two stop logs out of the weir and the lake level started dropping again, but two more large rain events towards the end of the month (1 inch on 27th and 1.34 inches on the 30th) brought us to 5.53 inches for the month and despite having opened the gate ¾ of a foot, the lake level rose back up to the top of the dam. We ended the month with a full lake and a full inch above November’s average rainfall. This brings us to 44.29 inches for the year to date, 3.67 inches more than average. Needless to say, the drought is over for this year. Continue reading →

May 2022 Water Level Chart Archived

May 2022

I have archived the May 2022 Water Level Chart (at left). From the beginning of the month on we saw an abrupt change from the above-average precipitation which has been the norm for the first 4 months of the year, almost as though someone had turned off the spigot! Total rainfall for the month was only 1.34 inches, well short of the normal 3.71 inches. Because we were 3.78 inches above normal at the end of April, we’re still 1.41 inches ahead of where we’d be in a “normal” year. However, simply looking at total precipitation gives you an unrealistic picture of actual ground water conditions: the fact of the matter is, the entire coast of Maine including Clary Lake is considered to be “Abnormally Dry” by the USDA Drought Monitor program. Continue reading →

Lake Water Quality Monitoring Resumes for 2022

Clary Transparency

Kelsie French and I resumed our water quality monitoring efforts for 2022 on Saturday May 14th, a little later than originally planned due to circumstances which all seemingly conspired to keep us off the lake. We’re back in the saddle now however and plan to visit Clary’s deepest spot to collect data every couple of weeks this season. Continue reading →

Clary Lake Association

Preserving and Protecting Clary Lake