Land use influence on water quality in the Saint Regis River

摘要

The influence of watershed land-use on water quality in the St. Regis River, a north-flowing river in northern New York State, was measured in October 2003 and April 2004 from the rivers headwaters in the Adirondack Park to its outflow at the St. Lawrence River, to determine a reliable indicator of land use that is most associated with fecal contamination within the watershed. Water samples were collected by grab samples from the shore of the river. Total coliform bacteria were enumerated using the Petri-Film™ technique. Bacterial contamination of the river increased downstream: total coliform concentrations ranged from 0 to 2,775 colony forming units per 100 mL. Localized regions of high bacteria concentrations existed, suggesting that nearby sources of fecal matter have a pronounced impact on water quality over short distances. In both October and April, high total coliform counts were positively associated with landscapes that had high coverage in pasture/hay or row crops, as determined using geographical information systems analyses. Dissolved nitrate and total phosphorus concentrations were highly correlated with total coliform concentrations dur-ing both high (April) and low (October) flow conditions. Water quality (total phosphorus, dissolved nitrate, turbidity, chlorophyll-a) and landscape-scale land use data suggest that total coliform inputs into the river are related to animal agricultural activity directly or due to ineffective treatment of human waste from residences in agricultural areas.