Water Supply Watershed Protection Program

Summary

The State of North Carolina requires any local government having land-use jurisdiction within a water supply watershed (areas where stormwater run-off flows to a drinking water intake) to adopt and implement water supply watershed protection ordinances, maps, and management plans. The purpose of the State program is to protect the quality of the drinking water supply for residents across North Carolina.

History

Water supply watershed regulations were first adopted by Henderson County on May 23, 1994. Henderson County was responsible for all watershed permitting in the Town of Mills River through 2020. After 2020, Henderson County relinquished their authority to conduct watershed permitting in Mills River and the Town took over this function. The Town of Mills River adopted its water supply watershed protection ordinances on December 8, 2022.

Watershed Districts

The Town has the following water supply watershed districts in its jurisdiction: Upper Mills River WS-II-C (Critical Area); Upper Mills River WS-II-B (Balance of Watershed); Lower Mills River WS-III-B (Balance of Watershed); and Upper French Broad River WS-IV-P (Protected Area). The Upper Mills River Watershed districts are in place to protect the water supply for the City of Hendersonville drinking water intake. The Lower Mills River and Upper French Broad River Watershed districts are in place to protect the water supply for the City of Asheville drinking water intake at the confluence of the Mills River and French Broad River.

Each watershed district has specific limitations to control the amount of stormwater run-off from a property due to development. Residential development is controlled through required minimum lot sizes per single-family dwelling or limiting the percentage of a property's land area covered with impervious surfaces that create new stormwater run-off. Non-residential development is controlled by limiting the percentage of the property covered with impervious surfaces. The table below has the requirements for each watershed district:

Water Supply Watershed Protection District Regulations on Density and Impervious Surfaces
	Low-Density Option		High-Density Option	Natural Drainage & Filtering Bonus
District	Lot Size	Maximum Impervious	Maximum Impervious	Natural Drainage & Filtering Bonus
WS-II-C	80,000 SF	6 %	24 %	N/A
WS-II-B	40,000 SF	12 %	30 %	N/A
WS-III-B	20,000 SF	24 %	50 %	N/A
WS-IV-P (Drainage & Filtering Bonus)	20,000 SF	24 %	70 %	Yes, Only Low-Density Projects
WS-IV-P (Drainage & Filtering Bonus)	14,250 SF	36 %	N/A	Yes, Only Low-Density Projects