MADISON, Wis. (AP) — Democratic Gov. Tony Evers’ administration is trying again to limit the levels of a group of chemicals known as PFAS in Wisconsin’s groundwater.

The Wisconsin State Journal reported that Evers authorized the Department of Natural Resources last week to begin work on administrative rules establishing limits. DNR officials have not said what limits they’re considering.

The rule-making process typically takes at least two years. Final rules are subject to approval by the governor, the Natural Resources Board and the Legislature.

The DNR began working in 2019 to limit PFAS in groundwater, surface water and drinking water and ultimately presented the Natural Resources Board with a package of rules establishing groundwater standards of 2 parts per trillion; a surface water standard ranging from 8 ppt, 20 ppt or 95 ppt depending on the type of PFAS and whether the water body is used as a public drinking source; and a drinking water standard of 20 ppt.

The board adopted the surface water and drinking water standards but killed the groundwater standard amid concerns that the cost of drilling new wells and installing treatment systems could cost wastewater plants and paper mills millions of dollars.

Republicans who control the Legislature allowed the drinking and surface water standards to go into effect in June.