North Pipe Lake

The LakeGrade rubric puts North Pipe Lake at a C: clarity at 5.8 ft, 29 µg/L of phosphorus, and a TSI of 52 signal an intermediate trophic state. Clarity is the limiting factor — phosphorus is reasonable but suspended particles or algal cells keep water transparency below Wisconsin norms.

A TSI in the eutrophic range signals a lake doing what nutrient-loaded waters do — supporting an active algal community at the cost of clear water. A maximum depth of 37 ft puts North Pipe Lake in the middle of Wisconsin's depth distribution. At 64 acres, North Pipe Lake sits below the Wisconsin median: a small water where shoreline activity has an outsized effect on water quality. Within Polk County's 74 graded lakes, North Pipe Lake ranks 44 — below the local median, though not at the bottom.

North Pipe Lake has at least one documented invasive species (Banded Mystery Snail), so boaters and anglers should observe clean-drain-dry steps when leaving the lake. The fishery includes walleye alongside the lake's other 5 documented species — a notable draw for Wisconsin anglers. The grade is based on limited monitoring — fewer than three independent measurement years contribute, so future updates may shift the letter.