Robbinsdale Staff Work To Protect Crystal Lake Water Quality

Jenna Wolf spends as much time as she can talking and listening to Robbinsdale residents about Crystal Lake. The 79-acre body of water has no natural inlet or outlet, and is ringed by homes and city parkland.

Crystal Lake in Robbinsdale

“Unfortunately people can put their grass clippings and leaf litter, they go into those storm drains. A lot of people don’t realize those storm drains–they don’t go to get treated before they go to our lakes,” said Wolf, less than a year into her job as the city’s water resources manager. “They go directly into our lakes and streams. So, those extra nutrients can cause algae blooms, and those can be harmful to humans.”

The city’s flocculation plant has operated for about a dozen or so years on the lake’s southeastern shoreline, and Wolf says it’s doing a fine job of helping remove one particularly pesky element–phosphorous–from the lake by adding aluminum sulfate to the water it draws in.

“The aluminum sulfate binds with the phosphorous, and then we actually physically take that phosphorous out of the water, and then we put that clean water back into the lake,” said Wolf. “We’re removing, permanently trying to remove as much phosphorous as we can.”

Another way the city is working to shore up the lake’s overall water quality is by reducing the number of carp that have invaded in recent years. Through a partnership and a grant in conjunction with the Shingle Creek Watershed District, the city got crews to come in and systematically remove the carp each of the last four years. Wolf says it’s working to get rid of a lot of the fish and it’s helping with the phosphorous issue, as the fish live along the bottom and that stirs up settled sediment that gets back into the water stream.

“We weren’t finding really large carp, we were not finding really tiny carp, so that would tell us that they were having these different recruitment classes, or age classes, but we weren’t really finding that,” she said. “We know that the carp aren’t reproducing really well–which is a good sign.”

Wolf said the city hopes to perform another carp survey later this year if possible.

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