Driving from Milwaukee to a lake worth swimming in

Pewaukee Lake in Waukesha County, Wisconsin. It grades B and the drive is 33 min, or 23.2 road miles. It is also the closest graded lake of any kind.

Not longer at all. The closest lake to Milwaukee is also the closest one grading A or B, so the cleaner water costs no extra driving.

29 of the 40 lakes here have a public access point on the record, and the closest is Pewaukee Lake, 33 min away, grading B. The rest of the table shows "Not recorded" where no access point was documented, which is not the same as no access — check with the managing agency before you trailer a boat.

By road, from downtown Milwaukee to the nearest public road at each lake, over the OpenStreetMap road network. They are free-flow times: no traffic, no time of day, no stops. Treat them as the floor, and add for rush hour and for the last stretch to the water.

No. The letter summarises years of phosphorus, nitrogen, algae and turbidity measurements — it describes the lake, not this afternoon. A beach closure, a bloom, or a heavy rain can change conditions on an A lake overnight. Check the lake's own page for its measurement record, and check the managing agency for current advisories before you get in.