Lake McCarrons in Minnesota is one of the most popular, and healthiest, lakes in the region. And its low phosphorus levels are a big reason it is so healthy. And a big reason its phosphorus levels are so is because of an alum treatment conducted by the Capitol Region Watershed District in the lake in 2004.
"[The treatment] seals the bottom sediments so phosphorus cannot be released," said Bob Fossum, of the District. Large-scale stormwater management has also contributed to the lake's current health; the nearby Villa Park Wetlands (which feed into the lake) had 20,000 cubic-yards of sediment removed.
For the full article detailing what steps the district has made to preserve Lake McCarrons' water quality can be found here or through the link available below.