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LakeQuality

Portsmouth Unit

Portsmouth Unit is a state park in Crow Wing County. 8 graded lakes are within 15 miles of the park, including Serpent Lake, Agate Lake, Nokay Lake.

Portsmouth Unit State Park spans an unrecorded acreage acres in Minnesota — a designated recreation destination with the full set of facilities the state park system provides. The park is paired with 8 graded lakes nearby — enough for a multi-lake visit. Average grade among them: B.

For visitors planning around water quality, the nearby-lakes list below is the practical tool: a park is only as good as the lake you intend to use it from, and the LakeGrade for that lake gives you the water-clarity, nutrient, and algal-pressure context you need.

Designation
State Park
County
Crow Wing County
Established

Nearby Graded Lakes (within 15 mi)

Lakes closest to Portsmouth Unit, weighted by size. Click a lake for its full water quality grade, fish species, and depth.

LakeCountyGradeSurface AreaDistance
Serpent LakeCrow WingA-1.9 mi
Agate LakeCrow WingB-2.8 mi
Nokay LakeCrow WingC697 acres7.6 mi
Pelican LakeCrow WingA8.3K acres11 mi
Unnamed LakeCrow WingB-3.5 mi
Island LakeCrow WingA-3.5 mi
Rabbit LakeCrow WingA-3.5 mi
Hay LakeCrow WingB-3.8 mi

Other Parks in the Area

Park location and metadata sourced from Wikidata. For trail maps, camping reservations, and current conditions, visit the official MN DNR. Lake grades are derived from EPA Water Quality Portal data using Metropolitan Council standards.

Source: EPA National Aquatic Resource Surveys, 2026.