Lake Thirty

Lake Thirty earns an A — water clarity, phosphorus, and chlorophyll-a all rate among the best monitored waters in Barron County. The three sub-grades — clarity, phosphorus, and chlorophyll-a — track close together, so no single parameter is dragging the average.

Mesotrophic conditions dominate at Lake Thirty: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. Lake Thirty reaches 27 ft at its deepest point — typical for Wisconsin mid-sized lakes, with seasonal stratification but limited cold-water refuge. At 75 acres, Lake Thirty sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Among the 38 graded lakes in Barron County, Lake Thirty sits at rank 14, above the county median.

An invasive species record — Chinese Mystery Snail — has been logged at Lake Thirty; Wisconsin DNR maintains the official infested-waters list. The fishery is bass-led, with 3 documented species across the lake's records. A documented public access point at Lake Thirty makes the lake usable for shore fishing, paddle craft, and trailered boats. Monitoring depth is thin here: the LakeGrade rubric is applied to a small number of sample years, and the grade will be revised as more data accumulates.