GVSU researchers studying high chloride, phosphorus levels in Grand Rapids lake
Al Steinman, director of the Annis Water Resources Institute in Muskegon, and graduate student Ellen Foley are keeping a watchful eye on a lake in eastern Grand Rapids after homeowners contacted Steinman to investigate the lake’s lack of aquatic life.
High levels of phosphorus and chloride, a component of salt, have created a dead zone deprived of oxygen along the bottom of Church Lake. While neighboring lakes haven’t exhibited the same abundant levels of phosphorus and salt, Steinman and Foley are concerned it’s only a matter of time until they start to see similar numbers.
“The top 20 feet of Church Lake is moderately nutrient rich, but it’s not problematic,” said Steinman. “Down below is this ticking time bomb of very high phosphorous and salt concentrations.
“Here’s the kicker, this is probably problematic throughout the state of any lake that is near a major road or thoroughfares that are being salted in the winter.”
In Church Lake’s case, it’s bordered by Fulton Street to the south, Michigan Street to the north and the heavily-traveled East Beltline Avenue/M-44 to the east. A tributary runs beneath East Beltline Avenue, feeding right into the lake. Residential areas developing along East Beltline Avenue can also be exacerbating the issue, said Steinman.
Data collected from the tributary revealed the chloride is also seeping into the soil. This means even during warmer months, when there’s rainwater flowing through the tributary, salt is leaching into the water and into Church Lake.
“The salt and phosphorus are at extremely high levels at the bottom of the lake,” said Foley. “The chloride makes the water more dense, so it’s sinking to the bottom, and it’s trapped down there.”
The U.S. Environmental Protection Agency lists the toxicity threshold of chloride at 230 milligrams per liter (mg/L). In Church Lake, chloride levels reach as high as 350 mg/L, said Foley, while in the tributary feeding the lake, chloride levels are as high as 1,000 mg/L.
“You get near 1,000 mg/L, you’re entering brackish water,” said Foley.
As for the phosphorus levels, Steinman believes they are the result of more than a century of agriculture and fertilizer application.
“When we see phosphorus content this high in systems around West Michigan, it usually means there was agriculture going on at one point,” Steinman said.
Steinman expects several months for the data to be analyzed before he delivers his report to the homeowners this summer. He added that addressing and solving the issue won’t be easy.
Steinman said the first problem that needs to be addressed is the high phosphorus content. If the salt levels are reduced first, then it gives the phosphorus an opportunity to rise to the surface and may kick off large algae blooms.
“This gets into a really dicey question,” said Steinman. “What are you willing to pay for, where do you balance your competing demands between road safety and environmental protection?”