Chapter 10: Appendix 199
Mortality and other compost, when applied to agricultural land, will be applied in
accordance with the nutrient management measure. The cornposting facility may
be subject to State regulations and will have a written operation and management
plan if SCS practice 317 (cornposting facility) is used.
Water and Sediment Control Basin (638): An earthen embankment or a combi-
nation ridge and channel generally constructed across the slope and minor water-
courses to form a sediment trap and water detention basin.
The practice traps and removes sediment and sediment-attached substances from
runoff. Trap control efficiencies for sediment and total phosphorus, that are trans-
ported by runoff, may exceed 90 percent in silt loam soils. Dissolved substances,
such as nitrates. may be removed from discharge to downstream areas because of
the increased infiltration. Where geologic condition permit, the practice will lead
to increased loadings of dissolved substances toward ground water. Water tem-
peratures of surface runoff, released through underground outlets, may increase
slightly because of longer exposure to warming during its impoundment.
Water Table Control (641): Water table control through proper use of subsur-
face drains, water control structures, and water conveyance facilities for the
removal of drainage water and distribution of irrigation water.
The water table control practice reduces runoff, therefore downstream sediment
and sediment-attached substances yields will be reduced. When drainage is in-
creased, the dissolved substances in the soil water will be discharged to receiving
water and the quality of water reduced. Maintaining a high water table, espe-
cially during the nongrowing season, will allow denitrification to occur and re-
duce the nitrate content of surface and ground by as much as 75 percent. The use
of this practice for salinity control can increase the dissolved substance loading
of downstream waters while decreasing the salinity of the soil. Installation of this
practice may create temporary erosion and sediment yield hazards but the com-
pleted practice will lower erosion and sedimentation levels. The effect of the
water table control of this practice
wildlife communities may
vary with the purpose and management of the water in the system.
Waterspreading (640): Divertin, or collecting runoff from natural channels,
gullies, or streams with a system of dams, dikes, ditches, or other means, and
spreading it over relatively flat areas.
Well (642): A well constructed or improved to provide water for irrigation. live-
stock, wildlife, or recreation.
has poor quality because of
use in the
environment or its discharge to downstream water courses the
be degraded. The location of the
must consider the natu-
environment. Hazard exists
well development and its operation and
to prevent aquifer quality damage from the pollutants through the
or accident, or
the well casing and the bore hole.
Water-Measuring Device: An irrigation water meter, flume, weir, or other wa-
ter-measuring device installed in a pipeline or ditch.