LIBERTY TOWNSHIP, N.J. (Warren County) — Recent monitoring of Mountain Lake by the New Jersey Department of Environmental Protection (NJDEP) and the Mountain Lake Community Association (MLCA) indicates that water quality conditions remain safe and typical for this time of year, officials announced Wednesday.
On Monday, August 4, NJDEP collected water samples from both the beach and the center of the lake. The results showed blue-green algae (cyanobacteria) levels of 23,875 cells/mL at the beach with a toxin level of 0.30 µg/L, and 32,500 cells/mL at the lake’s center with a toxin level of 0.28 µg/L. According to the Lake Association, “These are all relatively low levels, safe for swimming, and typical for this time of year.”
Further monitoring conducted by MLCA on August 5 confirmed favorable conditions. “Water clarity is 4 feet, which is typical for August. Surface temperature is 79 degrees, which is wonderfully average and quite a contrast to the past couple of weeks, when the temperature soared to a high of 88 degrees, the highest we’ve ever recorded,” the association reported. Their algae meter, or fluorometer, registered a reading of 6, which is considered moderately low.
The lake continues to exhibit seasonal stratification, a normal summer phenomenon. According to the association, “The lake remains well-stratified, with warm, oxygenated waters in the upper layer, and cold, anoxic waters in the lower layer. These are typical summer conditions.” Temperature readings revealed a gradual drop from 79 to 75 degrees down to 12 feet, followed by a steep decline to 52 degrees between 12 and 21 feet. The thermocline—the zone of rapid temperature change—is located around 15 feet, where oxygen levels also drop sharply.
“The Lake Association will continue monitoring the lake on a regular basis and provide updates as needed,” the organization added.
The association also encouraged residents to visit their tent during the upcoming Community Day to discuss any lake-related concerns: “We look forward to seeing everyone at Community Day. Please stop by our tent to say hello, and discuss any issues pertaining to the lake.”
