192 Chapter 10: Appendix
Management of the irrigation system should provide the control needed to mini-
mize losses of
and yields of sediment and sediment attached and dissolved
substances, such as plant nutrients and herbicides, from the system. Poor man-
agement may allow the loss of dissolved substances from the irrigation system to
surface or ground water: Good management may reduce saline percolation from
geologic origins. Returns to the surface water system would increase down-
stream water temperature.
The purpose is to effectively use available irrigation water supply in managing
the moisture environment of crops to promote the desired crop
response, to minimize soil erosion and loss of plant nutrients, to control undesir-
able water loss, and to protect water quality.
To achieve this purpose the irrigator must have knowledge of (I) how to deter-
irrigation water should be applied, based on the rate of water used by
crops and on the stages of plant growth; (2) how to measure or estimate the
amount of water required for each irrigation, including the leaching needs; (3)
the normal time needed for the soil. to absorb the required amount of water and
how to detect changes in intake rate; (4) how to adjust water stream size, appli-
cation rate, or irrigation time to compensate for changes in such factors as in-
take rate or the amount of irrigation runofffrom an area; (5) how to recognize
erosion caused by irrigation; (6) how to estimate the amount of irrigation
from an area; and (7) how to evaluate the uniformity of water application.
Lined Waterway or Outlet (468): A waterway or outlet having an
resistant lining of concrete, stone, or other permanent material.
The lined section extends up the side slopes to a designed depth. The earth above
the permanent lining may be vegetated or otherwise protected.
This practice may reduce the erosion in concentrated flow areas resulting in the
reduction of sediment and substances delivered to the receiving waters.
When used as a stable outlet for another practice, lined
the likelihood of dissolved and suspended substances being transported to sur-
face waters due to highjlow velocities.
Livestock Exclusion (472): Excluding livestock from an area not intended for
exclusion may improve water quality by preventing livestock from be-
down the banks, and by preventing manure deposi-
ing in the water or
tion in the stream. The amount of sediment and manure may be reduced in the
This practice prevents compaction of the soil by livestock and
and undergrowth. This may maintain or increase
Increased permeability may reduce erosion and lower sedi-
ment and substance transportation to the
channels from the application of this practice may reduce
Mole Drain (482): An underground conduit constructed by pulling a
shaped cylinder through the soil.