Water Clarity at Highland Lake

posted Jul 22, 2017, 10:50 AM by Joseph Bickard

What You Need To Know About Water Clarity At Highland Lake

Rosie Hartzler and Corey Hollowell  June 8, 2017

If I was to tell you that the most recent water clarity readings at Highland Lake were 5 meters, you might just shake your head as in “Huh?”  What is the big deal?  Does “5 meters” mean that Highland Lake is doing well or not?

A big part of water quality is water clarity.  However, how clear does a lake have to be in order to be a healthy lake?

Every lake is different.  Over time, water quality monitors at Highland Lake have established a pattern for how this lake works.  It is all about balance. 

Think about it.  If you like to fish in HL, how are fish going to survive if there is nothing there for them to eat?  On the other hand, if you are one of those folks who  when you think water, you think swimming and playing in the water, then you naturally want the water as clean and clear as possible. You want the water to be clear. 

Water quality monitors (certified by the Volunteer Lake Monitoring Program) have utilized the Secchi Disk to determine water clarity since the 70’s.  The disk is lowered into the water one meter at a time and monitors record the last depth at which the Secchi Disk is still visible.

Since early May,  four Secchi disk readings have been recorded at Highland Lake. Readings average 5.9 meters, which is “pretty good,” according to Tom Bannen, a water quality monitor on HL for 17 years.  (One meter = 3.28 feet).

I stated that it’s all about balance in a lake? Just because you can’t see to the bottom of our lake, does not necessarily mean that the lake is bad.  In fact if one could see to the bottom of the deep hole (67 feet is the deepest part of HL where the water clarity samples are consistently taken), this would indicate that there are no nutrients or microscopic plants and animals for fish to eat. 

Phosphorous ( a nutrient ) can really change the balance in a lake’s ecology. Historically, the primary reason for too much phosphorous in Highland Lake, has been development.    In the late 90’s Highland Lake was put on the Maine Department of Environmental Protection list of “lakes at risk from over development.” 

A lot of money, time, and resources were  invested in reducing the phosphorous runoff into the lake, and in 2010, the lake was taken off the list. 

The following graph depicts water clarity data for 2010.  Readings for the season indicate a fairly even pattern of water clarity. Note that on the left is the level of clarity as the Secchi Disk is lowered into the lake.  The higher the number, the greater the clarity in the lake.  The dates on the bottom are the days that water quality monitors tested for water clarity on Highland Lake during this season.

Jump to 2014. This season began with good water clarity readings.   In fact as depicted on this graph, water clarity was exceptionally good during the end of May and into the beginning of June. 

Then water clarity readings took a distinct turn in mid-July.  Water clarity was reduced to about 2 meters.  Then in mid –August,  good water clarity returned.

Then came 2015. Now that you know how to read graphs, you can readily see that like in 2014, water clarity readings decreased in an eerily similar pattern from mid -July to mid- August . 

The Highland Lake Association was sufficiently concerned about this disturbing pattern.  They determined to pursue a much more aggressive schedule for lake monitoring during the 2016 season.

Almost on que, the lake water clarity took a distinct turn during late July. Something was seriously out of balance in Highland Lake.  This prompted the Highland Lake Association to apply for grant funding from the Town of Windham to study what was causing this troubling change in water clarity.

Now we are in the 2017 season.  Water clarity readings are averaging 5.9 meters so far this season. All is well for now. 

The question is: What is happening below the surface - below that depth in the lake where the Secchi disc is no longer visible?    

Stay tuned.  The Highland Lake Association is committed to figuring out why the drastic change in water clarity readings has been happening over the past several seasons.   We are committed to figuring out what is causing the imbalance in the lake ecology.

At present, we know that microscopic bacteria, picocyanobacteria, may be part of the puzzle. This bacteria (which by its very name, sounds ominous) is actually present in marine and fresh water.  It is part of the food chain in our lake.   But, for some reason, this little “bugger” is getting out of balance in Highland Lake.

We need your help and invite your participation in the efforts to uncover the “culprit” that is causing the outbreak in Highland Lake from mid-July to mid- August.

Mark your calendar and make plans to attend the Annual Meeting of the Highland Lake Association on July 20, 2017 at the Cornerstone Church. Come early (6:00 – 6:30) and enjoy some food and drink with friends, before the meeting, which will run from 6:30 – 7:30 p.m.   This meeting will be a very informative meeting focused on “What is happening at Highland Lake?”

Go to our web site, www.highlandlakemaine.org  to learn more about what is happening on Highland Lake. While on the web site, go to the link that gives you instructions for how to become a member of the HLA.  There is also a link where you can make a tax-deductible donation to the HLA, as funds are needed to uncover the “culprit” at Highland Lake. 

Stay tuned here for upcoming articles in the Windham Eagle, about the situation at Highland Lake.  You can sign up for our email Newsletter to  always get the latest information on this threat to our lake.