Union Lake

The LakeGrade rubric puts Union Lake at a C: clarity at 5.5 ft, 21 µg/L of phosphorus, and a TSI of 50 signal an intermediate trophic state. Secchi readings are the weakest of the three parameters, suggesting suspended sediment or algal biomass dominates the optical signal.

At a TSI of 50, Union Lake reads as eutrophic — nutrient-rich enough that summer algal growth and reduced clarity are expected, not unusual. The lake bottoms out at 35 ft — a moderate depth that supports a warm-water fishery without the year-round cold refuge a deeper basin provides. Union Lake is small — 93 acres alongside 1.5 miles of shoreline — which makes it sensitive to even modest changes in watershed runoff or recreational pressure. Among the 64 graded lakes in Wright County, Union Lake sits at rank 24, above the county median.

Union Lake has no invasive species recorded in Minnesota state databases as of 2021, though prevention practices still apply at all access points. Walleye are documented at Union Lake, one of 15 fish species on record for the lake. Public access is available — the lake is on the Minnesota PCA public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.