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i i EXECUTIVE SUMMARY In 1983, two methoxychlor treatments of the Athabasca River for larval black fly control were monitored by the Pesticide Chemicals Branch of Alberta Environment, Environmental Protection Services, Pollution Control Division. Non-target benthic invertebrate populations were studied during the open water season to assess short term and long term effects caused by the methoxychlor treatments. Drift sampling (short term) showed a substantial increase (up to 1000 times) in the number of invertebrates collected in correlation with methoxychlor residue concentrations. On the other hand, bottom samples (long term) did not show immediate or long term changes because of the methoxychlor treatments. Water samples were collected in the Fort McMurray area because of the large domestic and industrial water demand from the Athabasca River.Methoxychlor residue levels of up to 2.0 parts per billion were detected in Athabasca River water. Trace levels of methoxychlor were detected in the City of Fort McMurray raw water reservoir, but residues were not detected in the treated drinking water supply.Sediment samples were collected from the Lake Athabasca Delta to determine whether methoxychlor was accumulating in this depositional area.No residues of methoxychlor or other pesticides were detected in the samples. jr https://archive.Org/details/monitOringofblac00byrt_0 Adult black fly data were compiled to assess the efficacy of the treatment program, and to compare the distribution of black flies within the endemic black fly problem area. The effect of river larviciding on adult black fly populations was evident when, in August, an untreated larval population emerged to create a severe attack on cattle in the northern section of the problem area. Throughout the summer, black flies were collected in low numbers in the southern part of the problem area around Grassland, and in relatively higher numbers in the northern section around Wandering River. 44

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The Coastal Plain of the United States has not been recognized traditionally as a region experiencing significant soil erosion because of its low relief and permeable soils. Measurements of soil profile truncation in cemeteries were used to estimate rates of surface lowering and soil erosion in Sampson County, on the Coastal Plain of North Carolina. Measurements of the depth to the top of the argillic horizon (DTA) in relatively undisturbed profiles in small, perched cemeteries (ranging in age from 99—180 yr) were compared with adjacent cultivated fields. The mean truncation of soils from ten study sites was 25.8 cm, with the mean surface lowering of 2.0 cm. Correcting for compaction, this translates to a mean soil loss estimate of 24.4&8211;27.4 Mg/ha/yr.