Agricultural N PS Control of Phosphorus in the New York State, Lake Ontario: Volume I - Delivery of Phosphorus to Lake Ontario from Cultivated Mucklands in Oak Orchard Creek Watershed Basin

Abstract

Cultivated mucklands in western New York State were investigated as a nonpoint source of phosphorus to Lake Ontario. The 70,500-ha Oak Orchard Creek watershed, which drains to Lake Ontario, was selected for the study area. It is located in Genesee and Orleans Counties, New York, and contains 3250 ha of heavily fertilized muck cropland on which predominantly vegetable crops are grown. The creek was monitored at several sites from May 1984 through April 1985 to determine the role of the mucklands in annual phosphorus loading to the lake. At an upstream site which drained approximately 10,200 ha, including the majority of the muck cropland, the creek load was 18,000 kg of total phosphorus with 75 percent of it as dissolved reactive phosphorus. Two-thirds of the annual load was delivered in the 3-month, high-flow period of February through April. Runoff during the late winter-early spring period appears to be the most important hydrologic factor in governing annual phosphorus loading from the mucklands, greater than either total precipitation or total runoff for the year. The pesticide DDT and its metabolites, DDE and DDD, were detected in muck soils and in creek suspended and bed sediments at this site. Although the annual loading rate of these compounds was thought to be relatively small, based on limited sampling, accumulation in the freshwater wetlands downstream which contain both a federal and a state wildlife refuge, could pose a hazard to sensitive species and warrants possible further investigation. A number of impoundments on the creek downstream of the mucklands, including the managed freshwater wetlands and two hydroelectric facilities, did not appear to significantly affect transport of phosphorus through the system during high-flow, late-winter months. In the largest impoundment, Waterport Pond, which is located 10 km from the creek mouth, internal loading of phosphorus from bottom sediments occurred during periods of hyrolirnnetic anoxia. Uptake and removal of bioavailable phosphorus by algae in Waterport Pond, rather than dilution by incremental flaw 1 was thought to account for a spatial phosphorus concentration gradient evident in summer months. The overall effect of Waterport Pond on annual phosphorus loading to Lake Ontario appeared to be removal of about 25 percent of the dissolved reactive form. Total phosphorus loading to Lake Ontario from Waterport Pond was 37. tonnes for the study year with 54 percent in the dissolved reactive form. Half of the load was delivered during the high-flaw months of March through May. A phosphorus load mass balance for Waterport Pond indicates that the greatest portion derives from the upper watershed containing the cultivated mucklands. Other smaller sources are the Village of Medina wastewater treatment plant and seasonal diversions of supplemental flow from the Erie Barge Canal. Control of phosphorus losses from the mucklands would appear to offer the most significant and cost-effective opportunities for loading reductions from this watershed.