Harmful algal blooms return to N.J.’s largest lake for the first time this year – NJ.com

Warning signs are popping up in the water of New Jersey’s largest lake.

Water samples collected by the DEP on July 23 found harmful algal blooms to be present at two locations in Lake Hopatcong: Mount Arlington Beach and the Lake Forest Yacht Club.

Both blooms were classified at the “watch” level on the state’s new advisory scale. That means that swimming areas remain open, but people should use caution before touching the water.

A third sample collected that day from Lake Hopatcong at Capp Beach found no bloom to be present. Before the three samples on July 23, DEP officials had sampled the lake five times between May 27 and July 16. None of those prior samples showed the presence of a harmful algal bloom.

Despite their label, the blooms are made up of cyanobacteria rather than algae. Contact with such bacteria can cause rashes and allergy-like reactions to flu-like symptoms and gastroenteritis. If the bloom is actively producing cyanotoxins, more serious health effects — like liver toxicity and neurological effects — may occur. The blooms can be fatal to dogs.

The bacteria that forms the blooms thrives in warm, calm water that is rich in nutrients like nitrates and phosphorous. Those nutrients enter the water when things like fertilizer and animal waste are washed into lakes after rain storms.

Last year, Lake Hopatcong became the poster-child for harmful algal blooms in New Jersey when a widespread bloom led to beach closures and warnings against water contact at the lake. That bloom, which was confirmed in mid-June and lasted until mid-November, took a heavy toll on the area’s tourism industry.

“So far, we’ve been pretty lucky,” Ron Smith, the chairman of the Lake Hopatcong Commission, said of this year. Smith added that he’s heard from marinas and other local businesses that tourism is doing fine, with folks around the state looking for things to do outside amid coronavirus restrictions.

Fred Lubnow, who works with the Lake Hopatcong Commission as part of his job as the director of aquatic resources at Princeton Hydro, said the blooms typically hit Lake Hopatcong in the late summer or fall. He added that blooms after Labor Day are not as high of a concern, because recreation on the lake tends to decline after that holiday.

Last year’s bloom in Lake Hopatcong was one of 39 confirmed around the state, the most in a single year since the DEP began formal monitoring of the blooms in 2017. In response to the rash of blooms, Gov. Phil Murphy announced a $13.5 million plan to help local authorities mitigate future blooms.

In March, nearly $650,000 of that money was granted for projects to help Lake Hopatcong. Smith said that money was initially delayed but is now on the way, and he added that the Lake Hopatcong Commission is “hoping for the best” with those projects.

The DEP has now confirmed 14 blooms in New Jersey this year, 13 of which are still active.

Recent weather makes it likely that more blooms will be confirmed in coming weeks.

Read more of NJ.com’s coverage of New Jersey water issues here.

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Michael Sol Warren may be reached at mwarren@njadvancemedia.com.