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J <br />• • <br />5 <br />'x <br />a <br />I~G^r•POIVT SWRCES <br />Pn indirect yet potentially significant source of contaminants <br />arises fran urban and rural runoff and drainage of unknown <br />origin into tributaries. <br />Zn a recent study conducted by Pgriculture Canada for <br />Environment Canada, it has been reported that about 2.5 million <br />kg of agricultural pesticides are used annually in the <br />agricultural land draining into the Detroit-St. Clair River <br />connecting channels. Approxi~rately 70~ of these pesticides have <br />been identified as potentially enviromentally hazardous. 41;tile <br />dccimientationn of the use of these agricultural pesticides is <br />camplete, the fate of these chemicals in the environment remains <br />unclear. Recent analysis of surface water (Thames River), <br />ground water (drinking wells}, and municipal drinking water <br />supplies by provincial authorities have identified high levels <br />of several of the pesticides used extensively in agriculture. <br />FVrther definitive dociumentation of this emerging issue is <br />recuired. <br />Surveys in 1984 and in 1985 by <br />have provided estimates of load <br />s::spended solids entering the <br />watersheds. In addition to <br />parameters, nutrients, phenols, <br />routinely analyzed. <br />the Ministry of the Environment <br />erg contributions Pram water and <br />St. Clair River Fran adjacent <br />conventional water chemistry <br />mercury and heavy metals were <br />~ditional organic canprdnds . measured, included PCBs, <br />chlorinated aranatics, chlorophenols, herbicides and pesticides. <br />Tvoically, 1984 organic contaminant levels under low flow dry <br />weather conditions were below detection levels with sane <br />exceptions associated with aqueous fraction as opposed to <br />suspended solids. <br />Elevated levels were also noted for the pesticides atrazine, <br />Ethion, and htevinphos in TalEord and Baby CYeeks. Tie latter <br />two were detected in July and possibly originate Fran <br />agricultural land runoff. <br />