The Wellhead Protection Area (WHPA) code is now available for distribution by the International Ground Water Modeling Center in Indianapolis, Ind. The WHPA code is a modular, semi-analytical, groundwater flow model developed for the U.S. Environmental Protection Agency, Office of Ground Water Protection. It is designed to assist state and local technical staff with the task of WHPA delineation.

The model consists of four independent, semi-analytical modules that may be used to identify the areal extent of groundwater contribution to one or multiple pumping wells. One module is a general particle tracking program that may be used as a post-processor for two-dimensional, numerical models of groundwater flow. One module incorporates a Monte Carlo approach to investigate the effects of uncertain input parameters on capture zones. Multiple pumping and injection wells may be present and barrier or stream boundary conditions may be investigated.