Amsterdam

Carroll County's principal overlays affecting ADU feasibility are: (1) FEMA NFIP Special Flood Hazard Areas — Carroll County participates in the National Flood Insurance Program (NFIP); the dominant flood-source watersheds are Conotton Creek (38.7-mile tributary of the Tuscarawas River draining ~286 sq mi of Carroll, Harrison, and Tuscarawas counties), Sandy Creek, Indian Fork, and the shorelines of Atwood Lake (Tuscarawas/Carroll counties) and Leesville Lake (USACE-managed reservoirs in the Muskingum Watershed Conservancy District); (2) MWCD shoreline/setback rules — both Atwood Lake and Leesville Lake are MWCD reservoirs, and parcels with lakefront frontage are subject to MWCD encroachment-permit requirements that overlay county/township rules; (3) coal-mining overlays — Carroll County sits on the Pittsburgh and other Allegheny-formation coal seams and has both historic underground and surface mining; subsidence risk in mapped undermined areas is a known constraint flagged by ODNR Division of Mineral Resources Management; (4) oil-and-gas overlay considerations — Carroll County has been one of the most heavily drilled Utica Shale counties in Ohio, with horizontal-well pad permits administered by ODNR Division of Oil and Gas Resources Management (not the county), but setback and surface-use constraints affect parcel buildability; (5) no county historic-district overlay — Carroll County does not operate a county historic-preservation commission, though individually-listed properties on the National Register exist in Carrollton and elsewhere.

• FEMA NFIP Special Flood Hazard Areas in Carroll County (Conotton Creek, Sandy Creek, Indian Fork, Atwood Lake, Leesville Lake shorelines) — Lake levels at Atwood and Leesville have repeatedly approached full outflow in wet years (recent reporting documents Carroll County flooding events tied to both reservoirs); a new ADU on a low-lying parcel near these waterbodies is a material cost-and-feasibility risk.
• Muskingum Watershed Conservancy District (MWCD) shoreline / encroachment overlay — Atwood Lake and Leesville Lake — MWCD does not preempt township zoning but adds an additional consent layer that can block or delay an ADU on a shoreline parcel.
• Historic and active coal-mining overlay (Pittsburgh and other Allegheny-formation seams) — Mandatory mine-subsidence insurance is built into homeowner policies in Carroll County; an ADU added to a covered parcel inherits the mandatory rider but the structure-specific underwriting should be confirmed with the carrier.
• Utica Shale horizontal-well pad setback considerations — Confirm any oil-and-gas surface easement at title search; this overlay does not require a county permit but materially constrains siting on affected parcels.