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[Abstract copied from conference proceeding, not paper itself] Following El Nino of 1982-83, a significant increase in burrowing shrimp abundance occurred affecting production for Washington State oyster growers.Environmental Protection Agency authorized aerial treatment of carbaryl over seed beds as well as bare ground on 800 acres in the state.Justification for treatment is based on general affects from burrowing shrimp to the oysters by: 1) a reduced growth rate and/or poorer condition of the oysters from feeding in competition with shrimp; 2) operational difficulties, 3) loss of seed and adults from smothering of fine sediments and sinking of shell in the softened substrate.The Environmental Impact Statement estimated a revenue loss of $5 million and 300 jobs could result without means to control burrowing shrimp.In response to concerns about the aerial application of carbaryl into the marine environment in Wallapa Bay, WA, alternatives were explored.Washington State Department of Fisheries provided the test area which had been a producing oyster bed until burrowing shrimp recruitment and establishment no longer permitted quality habitat for oyster production.Sub-surface injection was selected, targeting the burrowing shrimp.Carbaryl was injected into 36 plots, 5' x 15'.Injection rates of 3, 6, and 9 LB per acre with row spacing of 12 double prime , 18 double prime and 24 double prime established a basis for effectiveness.Twenty-four hours following injection resulted in a 50% reduction of burrowing shrimp for all plots.Subsequent low tide series showed a 99% control for selected rates and row spacing.Significantly more control was achieved using the 12 double prime row spacing as opposed to the 18 double prime and 24 double prime spacing for all rates.Within the measured groups using the 12 double prime row spacing, control was achieved using 66% less chemical than aerial application.This test series suggests that subsurface injection is an effective method with a significant reduction of chemical in the environment.(DBO)