Academic journal article Journal of Environmental Health

A Comparison of Wellhead Protection Area Delineation Methods for Public Drinking Water Systems in Whatcom County, Washington

Academic journal article Journal of Environmental Health

A Comparison of Wellhead Protection Area Delineation Methods for Public Drinking Water Systems in Whatcom County, Washington

Article excerpt

* The 1986 Amendments to the Federal Safe Drinking Water Act state that all federally defined Group A public water systems using groundwater sources are required to complete a wellhead protection plan.

* One strategy for protecting groundwater is to establish wellhead protection areas.

* A wellhead protection area is the land surface that lies directly over and recharges an aquifer that contributes water to a well.

* Under normal pumping conditions, this area is known as the zone of contribution.

* Recharge zones also are known as "capture areas."

* A capture area defines a surface beneath which infiltrated water will be "captured" by a well or well field.

* When a time-of-travel criterion is applied to capture areas, a time-related capture area is defined.

* The methods of delineating wellhead protection areas are as follows, from least to most costly and complex:

1. calculated-fixed-radius (CFR) method,

2. analytical models,

3. hydrogeologic mapping methods, and

4. numerical flow/transport models.

* The numerical method most accurately represents the flow system.

* The analytical method requires less time and expense than the numerical method.

* On the other hand, analytical models cannot be upgraded and improved as additional data are gathered.

* Both the numerical and the analytical models more closely reflect actual hydrologic conditions than does the CFR method. …

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