Cyanos Activity July 27

Water is clean for recreation.

Disclaimer: The information presented below reflects conditions throughout the lake and may differ from conditions on specific shorelines. For information regarding beach closings please contact the Torrington Area Health District or local town officials.

Water clarity at both the Center Lake and North Bay stations holding at 2, and 2,1  meters, however water was decided brown in color as opposed to green. Cyanobacteria numbers decrease dramatically to 1,300 in Center Lake and 6,900 in North Bay.  Higher cell number in North Bay was expected because less copper was applied in that basin by treatment design.  Clarity readings across the whole lake (11 stations were visited) were very similar, ranging between 2.0 and 2.2 meters, all having the same brown coloration.  The uniformity of clarity readings suggest decrease of cyanobacteria was lake-wide—samples were collected at all sites for a lake-wide assessment of effectiveness of the treatment and are under analysis.  Scums reported on 7-25-17, and 7-26-17 were not found during our visit on 7-27-17. 

The water temperature at the surface declined from 27 ^oC to 23.2^oC in 9 days, a loss of nearly 4^oC due to cold nightly temperatures over Monday and Tuesday nights.  Bottom water temperatures decreased by 2^oC since last visit which is possible only if cold ground water is entering the lake along a deep strata. 

Also significant is the lake-wide decrease in dissolved oxygen.  All stations had surface oxygen levels of between 6.5 mg/L to 7.4 mg/L, or about 80% saturated.  These low levels at the surface are due to loss of oxygen from decomposition of dead algae cells killed by copper sulfate.  Dissolved oxygen in surface should rebound quickly to fully saturated conditions in a few days. This loss of oxygen is illustrative of why only parts of a lake are treated with copper sulfate at one time. 

An additional cyanos treatment is scheduled for August 8, 2017.

Bantam Lake, CT 2017 Cyanobacteria Cell Count and CT DPH 2017 Recreational Waters Category Guidelines (Green = Safe, Yellow = Caution, Red = Posted Advisory)

Bantam Lake, CT 2017 Secchi Depth

Data is collected and analyzed by Northeast Aquatic Research, who is contracted by Bantam Lake Protective Association.