Lake Delton

The LakeGrade rubric puts Lake Delton at a C: clarity at 8.2 ft, phosphorus readings still being added, and a TSI of 47 signal an intermediate trophic state. 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 Delton: enough nutrients for a healthy fishery, not so much that algal blooms become a chronic problem. A maximum depth of 16 ft puts Lake Delton in the middle of Wisconsin's depth distribution. Lake Delton covers 249 acres alongside partial shoreline records — a mid-sized water that supports a working fishery without being so large that conditions diverge between basins. Within the 11 graded lakes of Sauk County, Lake Delton sits at rank 9, near the bottom of the county list.

Lake Delton is on the Wisconsin infested-waters list for zebra mussels — boaters should follow clean-drain-dry protocols when moving gear to or from the lake. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. Public access is available — the lake is on the Wisconsin DNR public-access list. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.