Estrogenicity and nutrient concentration of surface waters surrounding a large confinement dairy operation using best management practices for land application of animal wastes.

The impact of a confinement dairy operation (>2000 head) using best management practices for land application of animal wastes, on estrogenic activity (E-Screen), estrogens, and nutrients of associated surface waters and tile drain runoff were evaluated. Farm tile drain and creek samples were collected from the drainage region: above and below a municipal wastewater treatment plant located upstream from the dairy; and downstream from animal housing, parlor, and fields receiving applied wastes. Fifty-four thousand tons of waste (from approximately 1000 milking head) were applied to approximately 809 ha from April to July. Maximum estradiol equivalents (E(2)Eqs) present in tile drain samples (<or=0.257 ng/L) were 2-fold maximum creek E(2)Eqs, but only 25% of the proposed no observable effect concentration for E(2) (1 ng/L). Relative manure slurry estrogen concentrations were estrone >17alpha-E(2) > 17beta-E(2). Creek nutrient concentrations were similar above and below the dairy, with higher concentrations found in tile drain samples: tile ammonia ranged from <0.05 to 0.70 mg/L, nitrate/ite from 1.2 to 14 mg/L, and total phosphorus from 0.04 to 0.34 mg/L. No differences in estrogenic activity or nitrate/ite, ammonia, and phosphorus concentrations were detected in surface waters downstream of a large confinement dairy facility and measured nutrients were within regional norms.