Wis. Stat. § 33.48

The county or a municipality within the county may not reduce in any fiscal year its expenditures relating to environmental control of land surfaces below the expenditures it made in the fiscal year ending in 1990 if the county or the municipality makes the expenditures for the purposes of protecting or rehabilitating the quality of the surface waters and the groundwaters of the county. These expenditures include, but are not limited to, spending for erosion control, for construction site control, for environmental control of agricultural land and for conservation programs or projects but do not include extraordinary or nonrecurring expenses for these purposes.