The dead fish floated along the surface, covering much of Branch Brook Lake.
Catherine Marcal was stunned by the sheer number of them, stretching from the lion statues at the Prudential Concert Grove to the Park Avenue overpass.
But somehow, that was not the most disturbing image the Bloomfield resident saw earlier this month when she visited Branch Brook Park in Newark.
“A lot of them were still alive,” Marcal said. “They were still flip-flopping, and it was just horrifying.”
The fish die-off June 16 claimed hundreds of bluegill and pumpkinseed sunfish, plus a few largemouth bass, said Larry Hajna, a spokesman for the New Jersey Department of Environmental Protection.
”I had no idea that there were even fish like that living there,” Marcal said. “I couldn’t believe the quantity. There were hundreds and hundreds and hundreds of fish.”
Branch Brook Lake sits in the heart of Branch Brook Park — the largest stretch of open space in Newark and one of the crown jewels of the Essex County parks system.
It’s one of New Jersey’s iconic locales: An idyllic lake in a park sculpted by the famed Frederick Law Olmsted, in the shadow of the towering Cathedral Basilica of the Sacred Heart. Generations have come to its banks to unwind, get some fresh air and socialize.
But these days, all is not well in the water.
The fish die-off comes as the lake continues to be plagued by a persistent toxic algal bloom, which has been ongoing since September.
The Branch Brook Lake bloom was part of a record-setting wave of algae that spread across New Jersey in 2019. Climate change is expected to make the harmful blooms more common in the state, as temperatures rise and heavy rain events become more frequent.
Branch Brook Lake also had toxic blooms in 2017 and 2018. The DEP began its harmful algal bloom monitoring program in 2017.
Parks staff cleaned up the fish, said Anthony Puglisi, a spokesman for the county.
Some of the dead fish and water samples from the lake were sent to the DEP for necropsies and analysis. The DEP has examined the dead fish, but not determined a definitive cause of the die-off, Hajna said.
Multiple stressors, such as warm temperatures and low oxygen levels in the water, could have contributed to the incident.
“It is not unusual for these types of events to occur at this time of year, when water temperatures increase and dissolved oxygen decreases,” Hajna said. “The harmful algal bloom may have contributed to stressors in the pond, but is not believed to be the cause of the die-off.”
The blooms, caused by cyanobacteria, are potentially harmful to people and fatal to dogs. Contact with blooms can cause a variety of health problems, from 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.
Harmful algal blooms can also be a big problem for fish, according to the U.S. Environmental Protection Agency.
Essex County takes steps to try to slow algae growth in the lake, according to Puglisi. The lake’s picturesque fountains are part of that effort.
“While the fountains in the lake are nice to look at, their primary function is to promote the circulation of the water to prevent it from stagnating, which in turn leads to the growth of the algae,” Puglisi said. “In addition, we periodically spray the lake with approved chemicals to slow the spread of the algae.”
In November, Gov. Phil Murphy announced a $13.5 million plan to deal with the toxic blooms around New Jersey.
As part of that initiative, the DEP awarded $500,000 to the New Jersey Institute of Technology to study the effectiveness of floating platforms that will pump microscopic bubbles into Branch Brook Lake in an effort to improve water quality. NJIT will also develop a long-term harmful algal bloom strategy for the lake.
Branch Brook Lake has had an ongoing harmful algal bloom since 2019, and previously reported blooms in 2017 and 2018. Branch Brook Park, Newark, NJ, June 24, 2020.Michael Sol Warren | NJ Advance Media for NJ.com
The toxic algae in the lake is fed by nutrient pollution, which happens when materials high in phosphates — like fertilizers and dog poop — wash into the water during storms. But those nutrients aren’t the only thing carried by the stormwater.
Branch Brook Lake is surrounded by roads and parking lots, paved surfaces that collect oils and pollution from cars and trucks. The runoff washes the substances off the pavement, sending it flowing into the lake.
The threats posed by the algae and stormwater pollution are why signs have been posted, urging people not to eat fish pulled from the water or to let their pets play in the lake.
“In an abundance of caution, our policy through the years has been to not encourage people to eat the fish they catch in the lake,” Puglisi said. “Over the last couple of summers, the algae bloom also has contributed to that warning.”
It’s unclear when the water quality will recover enough for the warnings to be removed.
“The advisories have been in effect for quite some time,” Puglisi said. “We do not anticipate removing them in the near future.”
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.