(1) Area 1A description. Lands generally in the Mattawa area in the southwestern part of the county starting at the west end of the crest of Saddle Mountain at the Columbia River, south boundary line of Section 11, T15N, R23E; thence east along the crest of the Saddle Mountains approximately eighteen miles to the northwest boundary of the atomic energy reservation; thence southwesterly along the atomic energy reservation boundary to Highway 24; thence following Highway 24 to the Vernita Bridge at the Columbia River; thence northwesterly along the Columbia River to the point of beginning.

(2) Area 1A restrictions.

(a) The use or application of low volatile formulations of use restricted herbicides is prohibited on and after April 5th through October 31st: Provided, That low volatile ester formulations of 2,4-DB may be applied to alfalfa and red clover seed crops on and after November 1st through April 30th of the following year.

(b) Ground applications of use restricted herbicides on asparagus shall conform to the manufacturer's specified combination of nozzle type/size and pressure in pounds per square inch (psi) at the nozzle that produces a spray droplet size that falls within the coarse (or larger) range as defined by the ASABE standards.

(c) On and after April 5th through October 31st, aircraft applications of use restricted herbicides are prohibited except by written permit issued by the Washington state department of agriculture.