Documentation of a computer program to simulate horizontal-flow barriers using the U.S. Geological Survey's modular three-dimensional finite-difference ground-water flow model

This report presents a computer program for simulating horizontal-flow barriers in the Modular Three-Dimensional Finite-Difference Ground-Water Flow Model (MODFLOW) developed by the U.S. Geological Survey. Users of the report are encouraged to notify the originating office of any errors found in the report or in the computer program. Updates may be made occasionally to both the report and computer program.