A July 5 Fridley Patch post about swimming at Moore Lake ("") drew 16 comments at the Fridley Patch Facebook page—many of them questioning the quality of the lake's water.
How is the lake's water quality?
Mark Daly takes water samples in Moore Lake for the City of Fridley Parks and Recreation Department every two weeks. He provided the test data in the table below.
"When the e-coli numbers get over 200 [organisms per 100 milliliters] we look at retesting the water," Daly said by email Monday, "and if they come back high again we close the beach until we get acceptable readings."
Typically, Daly said, Moore Lake's E. coli count gets worse as the summer season advances—as borne out in the 2011 data below.
What causes the E. coli?
It’s hard to say. Contributing factors could certainly be goose poop. After a good rain you get the runoff water from the land where the geese have been. We do a goose round up this time a year just at Moore Lake to keep the geese population down. As you can tell from last year’s testing results we typically get higher readings later in the season. This is the result of from aquatic plants growth slowing and nutrients from decomposing aquatic plants becoming available for algae. The available nutrients, combined with warmer water and a lot of sunlight, can result in period of heavy algal growth, which can make the lake green and scummy. This is another reason we close Moore Lake in mid-August each year.
But overall, recent years have seen satisfactory water-quality test results, he said. "The last few years we have had very good readings for Moore Lake. I was just out today testing the water and it looked great," Daly said Monday. "I actually go in the water myself to test. If I didn’t feel comfortable about the water quality I would do it from a boat."
Water Quality at Moore Lake (E. coli, organisms per 100 milliliters)Date of Test Moore Lake South Moore Lake North June 7, 2011 17.5 32.3 June 20, 2011 31.3 27.9 June 29, 2011 31.5 34.5 July 12, 2011 8.5 11.0 July 25, 2011 77.6 82.0 Aug. 8, 2011 98.5 63.3
June 11, 2012 24.9 19.7 June 25, 2012 1.0 14.0
For more about water quality standards, see the attached Three River Park District document from 2006, or this Minnesota statute.