Life returns to the Shawangunk waters with easing of acidification

David Richardson (photo by Kat Cappillino)

Many of the ponds and lakes in the Shawangunks, Catskills and Adirondacks were what was known as “dead lakes” in the decades prior to the 1990 amendments to the Clean Air Act of 1970 which regulated sulfur emissions from coal-fired power plants. According to SUNY New Paltz biology professor David Richardson, a research associate at the Mohonk Preserve, “The pH levels of the water, which were around 4.5, were too acidic for most organisms to survive or reproduce. Fish eggs cannot survive in a pH of less than five.” Only microorganisms not visible to the naked eye could survive in that climate. 

Two of the local lakes considered “dead” were Awosting and Minnewaska, both now part of the 26,000-acre Minnewaska State Park Preserve. While bathers and hikers and outdoor enthusiasts still visited and enjoyed the “sky lakes” of the Shawangunk Ridge, there were no fish to catch or salamanders to spot.

‘Twas not always so. “Before the Clean Air Act went through, the last recorded time there were fish in Lake Minnewaska was back in 1922,” Richardson said. “There’s a picture of hundreds of yellow perch that were blown out of the lake [presumably] by dynamite because someone had been believed to have drowned. Kind of like one of the tales from Huckleberry Finn.” 


An attempt in the 1970s to stock Lake Minnewaska with hundreds of trout went belly-up, as none of the fish survived.

The sulfur levels blowing in from coal-burning power plants and factories in the Midwest were so high that they resulted in what was known as acid rain. This phenomenon became so toxic to water systems, soils and forests that science-based advocacy groups fought for and finally achieved pollution limits that have helped cut sulfur dioxide emissions by almost 88 percent between 1990 and 2017 ( “Although the regulations were enacted in 1990, they weren’t put into place right away,” explained the limnologist. “It wasn’t until about 1994 to 1995 that we started to see the impacts of those regulations. Over the past ten to15 years we’ve seen the pH in lakes move up to five, five and a half, six — what we would expect normal rainwater to be measured at. It was a huge win for science, advocacy and policy.”

Golden shiners show up

Lakes Awosting and Minnewaska now have a pH that can support a greater range of aquatic life. “I heard that Minnewaska used to be so clear, with no vegetation, that you could see 30 feet to the bottom,” Richardson said. “As the vegetation came back, so did the salamanders and other organisms. But it took a while for fish to show up. While the conditions can support fish, they have to actually get to the lakes. Minnewaska and Awosting are high up on the ridge, and there are streams and waterfalls and cliffs for fish to find their way to them.”

Somewhere around 2008 or 2009 people started to see small minnows, about four inches long, known as golden shiners, in Lake Minnewaska. “We don’t know how they got there, but they’re commonly used for bait, and maybe someone dumped a bucket of them into the lake …. We don’t know.”

The shiners had no predators in the lake, and they began to feast off the existing zooplankton. The plankton are what ate the algae. With the loss of the plankton, the algae went haywire. “The lake turned so green at one point that the lifeguards had to shut down the beach because they couldn’t see the swimmers.” This was somewhere around 2009 or 2010.

But then came the largemouth bass. “What do largemouth bass like? Golden shiners,” said Richardson. The bass fed off the golden shiners, and the zooplankton population came back, which helped to keep the algae at bay.

The shiners also attracted Northern water snakes, which live in and outside of lakes in the Northeast and like to eat minnows. There was a time period when those who love to swim at Lake Minnewaska were seeing more snakes in and around the water. Not coincidentally, this was around the same time that the golden shiner population had taken off. 

“This is only an anecdotal story, but I remember being at the lake at night, when we were doing some observation and sampling of minnows. We had a big cage of them by the swimming beach.” As Richardson remembers it, the naturalists went to empty out their cage full of minnows and saw “30 or 40 snakes descending on us. It was wild.”

The researcher hasn’t heard nor seen a sizable population of the Northern water snake since the shiners declined. The only known amphibian left at Lake Minnewaska is the Eastern red-spotted newt. “There used to be several species, but the big-mouth bass like salamander eggs,” he said. The reason they do not go for the spotted newt once hatched is thought to be because of “their orange dots, which indicate that they are poisonous. So they’ve been left alone.”

Climate change’s a threat

To Richardson’s knowledge, there has been no establishment of a fish population in Lake Awosting. “It’s slightly more acidic, even harder to reach than Lake Minnewaska, and less likely that someone would hike in three miles to dump some fish in,” he said.

Then there is the third “sky lake,” Lake Mohonk, on the grounds of the Mohonk Mountain House Resort and Spa. This lake did not suffer severe effects from acid rain, despite being only a few miles from its aquatic Shawangunk sisters.

“Lake Mohonk is at a lower elevation than the other lakes, and also has a shale base, which helps keep the water neutral,” Richardson explained. “The pH, which has been dutifully recorded by members of the Smiley family and the Daniel Smiley Research Center, has shown a similar pH measurement for the past 40 years.”

Thus the Smileys, who own the hotel, have been able to stock the lake with fish for its guests to enjoy for the past 125 years. The lake ecology is vibrant and plentiful.

While these three lakes are enshrouded by forests and natural buffers of preserved land, they cannot escape climate change. “We’re so fortunate to have these lakes and natural resources that are so well-protected and managed and loved,” Richardson said, “but that will not stop them from being impacted by global climate change. And we have to address that, because the temperatures are increasing at an alarming rate.”

With the steady increase of temperature and the loss of ice coverage (measured daily at Lake Mohonk), the entire lake ecosystem is changing drastically. The recreational activities have changed, too. “Historically, the lake was used to ski and skate and ice-fish, and that’s being lost,” Richardson said. Warmer temperature also changes the entire physical and chemical makeup of the lake, decreasing the water’s oxygen level, and is beginning to impact on the goods and services it has delivered for centuries to the flora, fauna, fish and wildlife that rely on these lakes.

It will take a coalition of research, science, environmental advocacy and policy to slow down the warming of our planet. Richardson feels that he’s fortunate to be able to study these issues and limnology with “such great partners like the Minnewaska State Park management team and the Mohonk Preserve.  Not only do they welcome the research and science, but they are also engaged in collecting that data to help inform their management and stewardship of the land.”