Treml County Park covers 18.2 acres in Section 32 of Leavenworth Township in Brown County. The park is on the East shore of Altermatt Lake and includes over 4,000 feet of shoreline.
In November 1987, the land was donated to Brown County by the Church of the Japanese Martyrs of Leavenworth for use as a day use park for picnicking and hiking.
The park was developed on the former Treml farmsite.
This is a day-use park offering a picnic shelter, shore fishing, open play areas and hiking trails in a quiet, rural setting. It was dedicated on Sunday June 6, 1993.