Category Archives: Water Quality

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

September 2021 Water Quality Update

Total Phosphorus Chart

Total Phosphorus Chart

The Total Phosphorus test results from our 8/6/2021 core water sample came back the other day at 0.035 mg/liter, the highest TP value we’ve ever recorded. This is ominous. The next highest value we recorded was 0.034 mg/liter in July 2007 (see chart at left). I don’t remember the particular circumstances surrounding that reading, but there was another high TP reading of 0.032 mg/l more recently, in July 2015 that I do remember. It coincided with a secchi disk reading of only 1.95 meters indicating an algae bloom was in progress (secchi disk readings of 2 meters and below indicate a bloom in progress). You can see this 1.95 meter data point on the chart showing Clary transparency below. In this particular case, extreme low water conditions were a major contributing factor to poor water quality!! I expected a high TP value this time because of the 9″ of rain received in July. Rain means runoff and runoff means soil erosion and sedimentation which is the primary source of Phosphorus in lakes, but still, I was surprised to see such a high number. High phosphorus levels are not good for water quality! We really need to update our Watershed Survey!

Despite the high phosphorus level, we haven’t seen a significant algae bloom yet this summer and we may not, though I did notice a few wisps of dead cyanobacteria along the shoreline back in August, and water transparency is currently holding up nicely: at our last the water monitoring session on Sunday September 5th, Kelsie French and I had secchi disk readings of 3.55 and 3.45 meters respectively which is about average, and better than expected considering the level of phosphorus in the water. Transparency could deteriorate quickly however and we’re going to keep a close eye on it; we will take our 3rd and final water sample for Phosphorus testing during our next water quality monitoring session in a couple of weeks. Continue reading

12 August 2021: Damariscotta Lake Blooms

Damariscotta Lake has been experiencing considerable cyanobacteria growth in recent years, a troubling condition that affects many lakes in Maine. Some lakes are big enough for these types of events to impact only certain areas, though they can be lake-wide. This particular algal bloom in Damariscotta is in the Mills area. So far this summer I’ve noticed only slightly elevated levels of blue-green algae (cyanobacteria) in Clary as evidenced by faint wisps of dead algae on the water surface and slightly reduced transparency in early August. This is most likely the result of runoff from heavy rains in July. A small amount of algae growth is  expected, and is more or less normal. Clary Lake however is by no means immune to severe algae blooms, defined as a transparency of 2 meters or less and while we haven’t experienced a severe bloom since 2014 (see chart at left), it can and will under the right condition happen again. It behooves us to be vigilant and minimize soil erosion on our properties to stop the introduction of sediment and phosphorus into our lake.

Algae Bloom at Damariscotta Mills Potentially Harmful

The Midcoast Conservancy staffer Patricia Nease who is monitoring the Damariscotta Lake bloom spoke at our recent Annual Meeting about the Invasive Plant Patrol program on Damariscotta Lake and things we should consider when starting up an IPP program on Clary Lake.

23 May 2021: Relax, It’s Tree Pollen!


Tree Pollen on Clary Lake

While this looks similar to the end stage of an intense algae bloom, it’s really only plant pollen. One telling difference is the color: this stuff is decidedly yellow whereas dead cyanobacteria is bright green.  I suspect it’s pollen from White Pine though I’m not sure. In any case, it’s a natural phenomena and there is no reason to believe pollen has an impact on water quality though for a short time it can impact lake water transparency. While it looks ugly, it is of a short duration and will eventually disperse into the water column and sink. Another difference between pollen and algal blooms is the timing: pollen events happen in the Spring whereas algae blooms are typically a mid-to-late Summer and early Fall phenomena. Here are a couple of pictures of cyanobacteria on my shoreline taken in October of 2013. The color is decidedly different:

img_3897-custom img_3896-custom

The more you know!

02 May 2021: Water Quality Monitoring Resumes for 2021!

46 Years of Secchi Disk Measurements

Kelsie French and I got out on the lake today to start Water Quality Monitoring for the 2021 season, a spring ritual that has been taking place on Clary Lake since 1975. All the data we collect is periodically sent to the Lake Stewards of Maine (formerly the Volunteer Lake Monitor Program) where it is checked for validity and accuracy. My father Stuart Fergusson was the first person to submit secchi disk readings for Clary Lake in 1975. David Hodsdon started accompanying him at about the same time and according to DEP’s Linda Bacon, David took over completely in 1991. For many years David worked solo until Jack Holland joined him around 2001. I got involved in 2013 and Kelsie French, our newest water quality monitor, started in 2018. After 44 years on the lake, David retired after completing the 2019 season and Jack Holland has taken a hiatus from water level monitoring. We hope he resumes sometime soon! Becoming a water quality monitor requires certification by the Lake Stewards of Maine, and periodic recertification. Continue reading

2020 Water Quality Monitoring Wrap Up

Dead Cyanobacteria

Dead Cyanobacteria 

We’re nearing the end of our water quality monitoring season. We’ve conducted 8 water quality monitoring sessions this year (a few less than normal because we got a late start) and will conduct one more session this coming week before calling it quits for the year. Many thanks to my associate Kelsie French for her help this year.

Yesterday afternoon when I walked down to my dock I spotted this dead algae washed up on my shoreline. Fifteen minutes after I took the picture, the green scum was gone. Remnants of an small algae bloom, it’s nothing to be alarmed about and there’s a very good explanation for what it is and why this occurred. Continue reading

02 January 2020: The Winter 2019 Water Column Issue Is Out

The Winter 2019 Lake Stewards of Maine’s periodical “The Water Column” arrived in our mailbox today. As usual, it’s full of interesting information about the state of lake water quality monitoring in Maine, invasive plant problems around the State, and other issues impacting lakes in Maine.

Last year’s Winter 2018-2019 issue of The Water Column was all about the impact of climate change on Maine lakes, and this winter’s issue continues their coverage of climate change with an interesting article on ice-in and ice-out trends. The Lake Stewards of Maine does a great job of publicizing their activities. The Clary Lake Association has been conducting water quality monitoring on Clary Lake in association with the Lake Stewards of Maine (formerly the Volunteer Lake Monitor Program or VLMP) since 1975 and is a long time supporting member of their organization.

Here’s a link to the full document:

The Water Column Winter 2019

15 October 2019: CLA’s Water Quality Monitoring Team Wraps Up Another Season

David-Kelsie-George-10-13-2019We’ve wrapped up another season of water quality monitoring on Clary Lake and took this selfie to celebrate. For David Hodsdon, this completes his 44th year of water quality monitoring (he started in 1975!). For Kelsie French it is her second, and for me, my sixth. Jack Holland also helps out when he can. I think he’s been doing it for close to 20 years. We’ve got a good team doing good work.

Clary’s water quality this past summer was better than what we’ve come to expect in recent years despite a mid-summer high Phosphorus reading of 0.028 mg/liter (the 4th highest we’ve ever recorded). That’s considerably higher than we’d like to see it. The high P sample was likely attributable to the 15″ of rainfall we received in April, May, and June as runoff from rainfall is the primary source for Phosphorus. We did see a small burst of cyanobacteria growth no doubt in response to the high P in the lake water, but it dissipated quickly and didn’t raise any real concerns. The results of our last Phosphorus sample (we take 3 samples per season) taken on September 27th) aren’t back from the lab yet. We’re hoping it shows improvement.

Clary Transparency

The average of 13 transparency readings over the summer was 3.6 meters (11.8 feet) which for Clary is Great! Transparency never fell below 3.15 meters (10.3 feet) and got as high as 4.20 meters (13.8 feet) in early May. You can see on the chart of secchi disk readings at left that overall transparency in 2019 easily bucked the historical downward trend we’ve seen during the years of our water level crisis. We expect our newly restored water level regime will result in good water quality going forward, but we’ve got to remain vigilant. Lakes are fragile ecosystems and many issues can affect water quality.

Here’s a link to our water quality monitoring data going back to the beginning of 2012. Historical data is available upon request:

18 September 2019: Maine Public Radio Program on Algal Blooms

Scott Williams of Lake Stewards of Maine

There is a new Maine Public program on algal blooms and climate change that is well worth watching (or listening to). Here on Clary we have avoided a severe algal bloom this season though we’ve seen them in the past; we did have a mild, short-lived bloom back in early July, no doubt brought on by a spike in phosphorus levels due to heavy rainfall and the resulting runoff in April, May, and June. While Phosphorus levels have remained high this summer, transparency has remained greater than 3 meters all season. We’ve been fortunate. We are most at risk however in September and October as the lake water “turns over” mixing phosphorus at the bottom of the lake into the upper layers of water where it can feed blue-green algae.

05 July 2019: Moderate Algae Bloom in Progress


Cyanobacteria coloring the water.

You may have noticed a green scum drifting on the lake surface recently or seen loads of green particles suspended in the water and thought it was pollen. Well, it does look a lot like the pine pollen that was blowing around last week, but that was yellow, and this stuff is green. Clary Lake is actually experiencing moderate blue-green algae growth resulting in an algal bloom. This early season algae bloom has no doubt been fueled by excessive runoff from all the rain this spring (15″ since the 1st of April!) which has introduced Phosphorus and other nutrients into the lake. Phosphorous is the primary food for plants and algae. Blue-green algae technically is a phylum of bacteria (cyanobacteria) that obtain their energy through photosynthesis. Another likely source of Phosphorus is rotting terrestrial vegetation. For years, better than 300 acres of drained wetlands have been growing grass, goldenrod, alders, and other terrestrial plants and that land is now under water, and the vegetation is rotting. This releases nutrients including Phosphorus in the water, helping to fuel aquatic plant and algae growth. Here are a few more photographs:

All this rainfall has also resulted in significant flushing of Clary Lake, well in excess of normal. Since January 1st, the lake’s entire volume of water (7,224 acre-feet) has been replaced almost twice. The inverse of the flushing rate is retention time (how long water stays in the lake) and that figure has decreased to about 92 days. The published “flushing rate” for Clary Lake is 1.81 times per year. We’re going to exceed that value by a significant amount. This will help “wash out” the nutrients currently in the lake, but will also result in more nutrients being brought into the lake. This is why controlling non-point sources of soil erosion and sedimentation is So Important: it doesn’t help replacing nutrient-laden water with more nutrient-laden water.

I expect this current algal bloom to dissipate soon, and it remains to be seen if we’ll have additional algae growth this year. Under the circumstances, I wouldn’t be surprised. It is important to remember that even though the dam has been repaired and the lake level restored, the ecology of Clary Lake has been severely damaged as a result of the 8 years of low water and it going to take some time to recover. Clary is still at-risk from both natural and man-caused issues and deserves our ongoing attention.