Nielson Lake

Nielson Lake grades an F: water clarity, phosphorus, and chlorophyll-a all rate poorly, placing it among the most stressed lakes monitored in Minnesota. Sub-grades cluster within a single letter of each other, which usually means the lake is in stable trophic balance rather than fighting one specific stressor.

Hypereutrophic conditions mean the lake is operating at the upper end of the productivity scale, with all the bloom risk that implies. The lake's maximum depth is not yet documented in state morphometric records — context for its physical structure remains limited. The lake's surface area is not consistently recorded across state datasets — physical context remains partial. Within the 83 graded lakes of Washington County, Nielson Lake sits at rank 81, near the bottom of the county list.

No invasive species are currently listed at Nielson Lake — the lake remains off the Minnesota infested-waters roster. The state fisheries records do not list documented species for Nielson Lake, which usually reflects a lack of formal fisheries survey work rather than an empty lake. No formal public access is documented at Nielson Lake — most use is by shoreline residents and their guests. The grade is supported by multiple sampling years from Minnesota PCA volunteers and partner agencies, giving the letter a reasonably stable foundation.