Staff and developer explain floodplain, floodway and compensatory-storage implications for Wellspring ponds and trails

Planning staff and the developer briefed the commission about floodplain, floodway, and compensatory storage constraints that affect Wellspring’s ponds and potential trail locations. Haley Durham said the applicable code requires a 100-foot floodway setback and that the city only receives compensatory-storage credit for excavation above groundwater — excavation below groundwater does not count toward compensatory storage calculations.

Haley explained that a trail in the floodway is not precluded but would demand extensive engineering and documentation to demonstrate no adverse hydraulic impacts. “Anything that's shown here within the red and blue striped area is considered floodway. That is the most prohibitive zone in terms of development,” she said, adding that pathways in floodway require hydraulic modeling and FEMA coordination. The developer noted they have provided flood-control emergency access and reviewed that access with the flood control district, and that the central pond was intentionally deeper (20–25 feet) for water-control and temperature reasons.

Commissioners asked whether building a north-side regional trail would be feasible given the floodway and ownership of adjacent lands; staff noted it would require coordination with Idaho Department of Lands and possibly ACHD standards if it connected to public roads. The commission recorded its preference that future planning consider a north-side regional pathway where practical but recognized added costs and engineering complexity if construction were located in the floodway.