Seneca Lake is entering the traditional peak season for harmful algal blooms while its water level continues to fall, with efforts to stop an ongoing leak at the Seneca Falls dam so far unsuccessful, according to the latest update from Seneca Lake Pure Waters Association.
The lake stood at 445.23 feet Friday morning, Aug. 28, and Pure Waters warned that without significant rainfall it could drop below 444.5 feet before the end of October. The organization said Seneca Lake is already lower than it was at this point last year, raising concerns about conditions heading into the fall.
Pure Waters said it received an informal response Wednesday related to its Federal Energy Regulatory Commission complaint indicating attempts to plug the leak at the dam have not worked. Sending a diver to address the problem was considered too dangerous, according to the organization, meaning the leak is expected to continue until November, when water can be lowered behind the dam.
Pure Waters advised shoreline property owners and lake users to prepare for potentially lower water levels in the weeks ahead.
The warning comes just before Labor Day weekend, traditionally one of the final periods of heavy recreational activity on the lake.
HABs return as lake begins to cool
Pure Waters also reported three confirmed harmful algal blooms between Aug. 21 and Aug. 27.
The first confirmed blooms of the season were reported last Friday in the northeast and northwest portions of Seneca Lake. A third was confirmed Tuesday near Himrod in the southwest portion of the lake.
The organization said the lake is beginning to cool from its summer high, a period that typically coincides with increased HAB activity, particularly during stretches of calm weather.
Surface water temperature was 73.2 degrees Friday morning at a depth of 3.3 feet, according to Finger Lakes Institute monitoring data. Dissolved oxygen measured 111.5% in the upper 30 feet Thursday evening.
Pure Waters is urging residents and visitors to watch for water that resembles pea soup or spilled paint, bright green or blue-green coloration, surface scum, green streaks or mats collecting near shorelines and quiet coves.
People who encounter a suspected bloom should avoid contact with the water, keep pets out and report the observation to the state Department of Environmental Conservation and Pure Waters.
New cyanobacteria finding adds to monitoring
The update also follows the first identification of benthic cyanobacteria through Pure Waters’ Seneca Lake monitoring program.
Unusual debris recently photographed near Lakeshore Landing, north of Sampson State Park, was sampled by a volunteer and visually identified by the Finger Lakes Institute as benthic cyanobacteria from the genus Oscillatoria.
Unlike the HABs commonly seen near the surface, benthic cyanobacteria grow along the lake bottom and can form mats on rocks, sediment and vegetation. Pieces can detach and float toward shore.
Pure Waters has stressed that the finding doesn’t establish that benthic cyanobacteria are new to Seneca Lake, only that they have now been documented through its monitoring program.
The organization is advising people to avoid unusual mats or clumps and keep children and pets away from suspected material.
Pure Waters said it will continue monitoring HAB activity, lake levels and the dam leak as conditions change through late summer and fall, with additional information on the falling lake level expected next week.
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