Downward Movement of Water Below Barnyard Grass Filter Strips
                           Case Studies


                           Introduction

     The pollution potential from barnyard and exercise area
runoff has been of concern to farmers and conservationist
throughout Wisconsin. In Wisconsin, legislation has been passed
to prevent water quality problems from mismanaged animal wastes.
Under NR 243 of the Wisconsin Administrative Code, livestock
operations that exceed 1,000 animal units or those less than
1,000 animal units where a pollution hazard has been identified
are required to submit a runoff management plan and obtain
approval from the Wisconsin Department of Natural Resources for
their operations. Under Administrative Code AG 165, counties are
required to develop animal waste management plans and zoning
ordinances which require control systems and storage facilities
meeting Soil Conservation Service Standards. Even where
pollution potential from barnyards and exercise areas is thought
to be low, many farmers have installed runoff control facilities
as a part of their total management system.

     Barnyard runoff control may be achieved through several
alternatives. Often the alternative selected involves a
combination of engineering and management practices which control
or treat runoff prior to discharge. Grass strips which filter
barnyard effluent and encourage infiltration of the runoff water
are generally recognized as an economic alternative for the
control of potential pollutants in runoff from many barnyard
facilities. As used in this study a grass filter strip is
defined as an area of permanent vegetation developed to receive
barnyard runoff and to reduce the pollution potential of the
runoff water through the filtration of solids in the surface
runoff and through the infiltration of water and nutrients into
the soil where they can be used by plants, transformed within the
soil system, or adsorbed onto the soil particles.

      It is important to recognize that the grass filter is only
one component of an effective runoff control system. Other key
components include:

      "Clean" water diversions:  "Clean" water diversions include
      roof gutters and diversions which route relatively clean
      runoff water away from the barnyard and filter area.
      Diversions limit the runoff water's ability to transport
      pollutants by limiting the amount of water flowing across
      the barnyard area and reduce the volume of water that must
      be treated within the filter area.

      Solids settling basin: Most runoff Control systems in
      Wisconsin include some provision for settling solids in the
      runoff water before discharging the water onto the grass
      filter.  The basin may be an integral part of the barnyard or