A recent article on a cooperative, community-driven approach to culvert mapping explores the goals of the Wisconsin Coastal-Management Data Infrastructure project (WICDI).
The answer is…. complicated.
The most common source of hydrography (rivers, streams, lakes) data in Wisconsin is the Wisconsin DNR’s “24k hydro” database. The DNR 24k hydro dataset is the most common starting place for most users in the state. Because the DNR data are limited to Wisconsin, users who need entire watersheds that cross the state border should investigate the National Hydrography Dataset (NHD) maintained by the U.S. Geological Survey.