Em4885 irrigation management practices to protect ground water

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The Chapter also defines “special protection areas” where ground water requires special
consideration or increased protection due to a number of possible reasons. An area may be
designated as a special protection area if it is a sole-source aquifer.
An important concept embodied throughout the Chapter is “. . . all known, available, and
reasonable methods of prevention, control and treatment . . . ,” known by the acronym AKART.
For example, in setting enforcement limits, the Chapter states, “All enforcement limits shall, at a
minimum, be based on all known, available, and reasonable methods of prevention, control and
treatment.” When discussing the approval of quality evaluation programs the Chapter states, “. . .
the evaluation program...shall include information on . . . the reliability of all known, available,
and reasonable methods of prevention, control and treatment . . . . ” And finally, when discussing
implementation and enforcement of the ground water quality standards, “This chapter shall be
enforced through all legal, equitable, and other methods available to the department including, but
not limited to . . . evaluation of compliance with all known, available, and reasonable methods of
prevention, control, and treatment of a waste prior to discharge . . . . ”
The Practices presented in the Manual, if implemented correctly and appropriately, are intended
to accomplish the purposes of AKART. However, it is important to note that implementation of one
or more of the Practices may not be sufficient to protect water quality to the degree necessary.
Assessment of ground water quality
Assessment of ground water quality is difficult as Washington does not have a comprehensive
ground water monitoring program. However, what information is available indicates that pollution of
ground water, either real or potential, is a serious concern. This concern is highlighted by the fact that
approximately 60% of the state’s population receives its drinking water from ground water sources.
For example, a pilot testing program in the late 1980s in Yakima, Franklin, and Whatcom
Counties tested 27 wells in each County for 46 pesticides and nitrate contamination. Of the 81
wells tested, 23 tested positive for at least one of the pesticides and seven exceeded drinking water
standards. Sixty-one of the wells tested positive for nitrates, at concentrations ranging from .10 to
24.4 mg/L, and 18 exceeded the 10 mg/L standard for drinking water.
Results from a study of ground water quality near Gleed (located about 5 miles northwest of
Yakima) were released by Ecology in December 1992. Twenty-seven wells were sampled and
analyzed for 74 compounds. Xylene was detected in five of the wells, arsenic in 13 of the wells,
copper in 23 wells, and lead in 11. Nitrate plus nitrite-nitrogen was found in all tested wells at a
mean concentration of 2.9 mg/L. However, none of the chemical concentrations exceeded drinking
water standards. Also, sources of the chemicals could not be identified.
The results of a study of ground water quality in the Quincy area were released by Ecology in
March 1993. Twenty-seven wells and two field drains were sampled in May 1991. One or more
pesticides was detected in 26 of the wells and both drains. Ethylene dibromide was found at 62%
of the sites and concentrations exceeded drinking water standards in nine wells and one drain.
Concentrations of nitrate plus nitrite-nitrogen exceeded drinking water standards in two wells.
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