Delineation of source water protection areas is the process of defining the area of land in which activities are likely to impact the quality of the drinking water source. Sources of water are divided into three zones. The delineation method is dependent on several factors, depending upon the source type, as described below.
What follows are the minimum criteria used to define these protection zones; individual protection areas may vary somewhat, based on individual circumstances or a desire by the local water planners to protect a larger area than the minimum.
• • If the watershed extends for less than 25 miles upstream of the intake, the water supply protection area (Zone III) extends the entire watershed yet is segmented (where size permits) into a Critical Zone (Zone I) and a Zone of
Responsibility (Zone II), according to the following scheme.
• • If the watershed extends more than 25 miles upstream from the point of intake, the water supply protection area includes three protections zones.
Zone I – The Critical Zones begins ¼ mile below the intake and extends 5 miles upstream of the intake along any stream that is 3 rd
order or above (on 1:24,000 scale maps), and including ¼ mile on each side of those streams (or to the nearest watershed boundary if it is within ¼ mile).
[Note: This is in keeping with Kentucky’s “five-mile” wastewater discharge policy which prohibits permitted (KPDES) discharges within five miles upstream of a water supply intake.]
Zone II – The Zone of Responsibility extends the protection area to 10 miles above the intake along the source stream and any tributaries that are 3 rd
order of above (on 1:24,000 scale maps). It includes the Critical Zone and increases the total width to ½ mile on each side of these streams (or to the nearest watershed boundary if it is within ½ mile).
Zone III – The Zone of Potential Impact extends to 25 miles above the intake along the source stream and any tributaries that are 3 rd
order or above (on 1:24,000 scale maps). It includes the area of any 14-digit hydrologic unit that is adjacent to these streams.
• • For most intakes that draw from reservoirs, the water supply protection area will include the entire watershed, segmented (as size permits) into subsections according to the following scheme.
• • For intakes in extremely large reservoirs (e.g. Grayson Lake), the water supply protection area includes three protection zones. These are intended to

parallel the protection areas used in the Wellhead Protection Program. If the intake is in a river embayment or the upper reaches of the reservoir, segmentation rules for river intakes may apply.
Zone I - The Critical Zone begins ¼ mile below the intake site and extends 1 mile upstream of the intake, measured in the thalweg (channel), and on the land along each side, ¼ mile from normal pool level of the reservoir (or to the nearest watershed boundary if it is within ¼ mile), and up 3 rd
order streams. If this segment of the reservoir is more than ½ mile wide and the thalweg is on the intake side of the reservoir throughout this segment, the Critical Zone may include only the intake shore of the reservoir.
Zone II - The Zone of Responsibility extends the protection area to 5 miles above the intake and to ½ mile on both sides of the reservoir (or to the nearest watershed boundary if it is within ½ mile). The protection area also extends into any tributaries that are 3 rd
order of above (on 1:24,000 scale maps), for a distance of 5 miles above the intake.
Zone III - The Zone of Potential Impact extends the protection area to 10 miles above the intake and includes the area of any 14-digit hydrologic unit that is adjacent to any stream that is 3 rd
order or above.
All public water systems using groundwater as their source, must delineate, inventory, and manage a wellhead protection area. The following describe the delineated wellhead protection area (WHPA) boundaries.
WHPA–1: The criteria for WHPA-1 is based upon a 180 day time of travel (TOT) or 400 foot fixed radius, whichever is greater. This area is delineated to protect against microbial contamination. This criterion is based upon U.S. EPA research regarding the survivability of viruses in groundwater. This research shows that certain pathogenic viruses can survive up to six months in a groundwater environment.
WHPA-2: The criterion for WHPA-2 is based upon a 10 year TOT. This represents the theoretical distance in which groundwater move within ten years. This area is delineated to protect against chemical and radiological contaminants from entering the well field and to allow for remedial measures in case of an incident.
WHPA-3: The criterion for WHPA-3 is based upon the zone of contribution to the well field. This area is delineated to show the maximum area providing water to the wellfield so that future activities may be located outside the area.