Keeping it “Green” in New Jersey: How a toxic slime ruined the summer for Lake Hopatcong communities, and what we can do about it


Keeping it “Green” in New Jersey: How a toxic slime ruined the summer for Lake Hopatcong communities, and what we can do about it

Last Monday, The New York Times covered a local crisis in our very own watershed resulting from record-high levels of toxic green algae in New Jersey’s largest lake, Lake Hopatcong. The four towns touching the lake historically benefitted from a buzz of summer activity on the water like swimming, boating, and water skiing, but this summer residents and visitors are banned from even touching the lake for their own protection. And many miles away, millions of others have reason to be concerned over this development: water from Lake Hopatcong is part of our shared natural water system, draining to the Musconetcong River and eventually into the Delaware main stem. The good news is, it’s entirely possible for public and private partners to mobilize the funding needed to limit this pollution and restore our waterways for recreation. But as leaders from our grantees New Jersey Future and the New Jersey Highlands Coalition point out in the article, there has to be synchronized cooperation on all sides for any of these efforts to have impact.

To understand how these algal blooms happen in the first place, we need only look at New Jersey’s number one ranking as the most densely populated state in the country. Even relatively protected regions like the New Jersey Highlands are almost completely built out, and those countless acres of paved surfaces, from asphalt parking lots to traditional rooftops, pose a singular threat to New Jersey’s waterways: with the increased rainfall and major storms that come with climate change, all that water needs to go somewhere. As sewer systems become overwhelmed with rainwater, the excess more often than not runs directly off of those paved or impervious surfaces straight into our waterways, picking up toxins and nutrients from sewage and fertilizer along the way. As polluted stormwater and warming temperatures reach critical levels, harmful algal blooms result.

A photo of the Lake Hopatcong algal bloom. Photo credit: NJ Department of Environmental Protection.


This problem isn’t unique to Lake Hopatcong. The issue of stormwater impaired waters extends across the state of New Jersey (see map), and the worldwide climate crisis is only making things worse. More extreme rainfall events and more heatwaves are increasingly leaving our waterways unfit for any kind of recreation or human contact. The consequences of contaminated rivers and lakes aren’t simply that they limit our fun – they hit us in our pocket. Just imagine what would happen to Cape May County’s $6.6 billion tourism economy if toxic pollution closed its beaches to recreational use – a frightening possibility that some will recollect as being an all too real occurrence not very long ago. Such economic hardship can occur in any town like those surrounding Lake Hopatcong where recreation and ecotourism drive the summertime economy. Statewide, New Jersey’s outdoor recreation economy generates $18.9 billion, and water sports account for more than one third of that revenue. Simply put, there’s a clear connection between our impact on the land, the purity of our waters, and the strength of our local economies. 


By choosing to invest in smart solutions, we can avoid another incident like the one in Lake Hopatcong. Cities and towns can use nature itself to build defenses against polluted stormwater and flooding by building up their Green Stormwater Infrastructure (GSI). This infrastructure comes in many forms including familiar ones like rain gardens, green roofs, street trees, and sidewalk planters, which all contribute to triple bottom line benefits for people, profit, and our planet. Studies show that every dollar spent on GSI, which reduces flooding and captures pollution, generates anywhere from $7 to $27 in future cost savings. Meanwhile, investments in greening our communities are shown to improve property values, reduce crime, and create jobs.

So while GSI does come with a cost, the benefits are worth it. A variety of federal and state funding programs are available, but typically require local match. As the Times article mentions, an impervious cover fee – even a below average one – can make meaningful progress and fund significant amounts of natural infrastructure needed to combat stormwater pollution. To use New Jersey as an example, even a below-average fee for impervious cover could still raise $500 million per year statewide, dollars that could spruce up and “green” our communities with attractive trees and plantings, while helping us to avoid “greening” our waters with toxic slime.

A rain garden in Northern Liberties installed to capture and filter pollution from stormwater runoff. Photo credit: Philadelphia Water Department.


From an environmental perspective, we are at a monumental inflection point. On the one hand, after 40 years of the U.S. Clean Water Act, our much cleaner waterways are experiencing a renaissance moment and supporting more recreation than we’ve seen in decades. At the same time, we’re staring down mounting threats from stormwater pollution that could reverse all of the progress we’ve made. More than 2,700 miles of streams across the Delaware River Basin (including NJ, PA, NY and DE) are stormwater-impaired, but government and NGO efforts are driving restoration efforts to repair this damage and avoid future pollution. We are proud to fund nonprofits who are doing this work and providing support to cities and towns that are ready to step up and take action, and recently provided $1.5 million in combined support to organizations including the New Jersey League of Conservation Voters Education Fund, New Jersey Future, New Jersey Highlands Coalition, Association of New Jersey Environmental Commissions, and Pinelands Preservation Alliance. More action is needed to manage stormwater runoff through effective policy and land use - we can and must do the work together.


This post draws on original research and analysis conducted by John Nguyen, environmental fellow with the William Penn Foundation’s Watershed Protection team.

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