County staff warned that the Idaho Department of Water Resources (IDWR) has interpreted Senate Bill 1083 to restrict irrigation from domestic wells in subdivisions approved after July 1. The interpretation, staff said in the June meeting, would require developers to provide mitigation — typically surface water rights and pressurized systems — before allowing any irrigation tied to subdivision domestic wells.

That interpretation, staff told the Jefferson County commissioners and department heads, differs from what some local officials and developers had expected for one-acre and half-acre lots. Under IDWR’s reading, domestic wells in newly platted subdivisions could not be used to irrigate lawns unless a mitigation plan using surface water is in place. Officials said older plats approved before July 1 would be governed by prior rules and remain unaffected.

County staff described multiple follow-up steps. They reported phone calls with IDWR and water attorneys and said they are lining up participation in mitigation groups and considering purchases of surface water to protect county water users from curtailment. Staff also told commissioners that the issue has driven a surge in calls to local well drillers and developers seeking to file plats before the July 1 date.

Why it matters: staff said the interpretation could affect property values and the viability of some subdivision plans that relied on domestic wells for household and landscape uses. The policy also may require developers to install community water systems tied to surface water rights, which would add cost and complexity to new residential projects.

County staff said they will continue discussions with IDWR, will participate in mitigation proceedings, and will update the board as the agency clarifies the rule or issues formal guidance.