Point Source Loadings of Phosphorus to Lake Erie: 1986–1990

Abstract

Point source phosphorus control became a priority with all of the jurisdictions around Lake Erie since the signing of the Great Lakes Water Quality Agreement in 1972. Major municipal sewage treatment plants were limited to 1 mg/L total phosphorus and phosphorus loadings to Lake Erie have decreased significantly. Recent estimates of point source loadings from municipal and industrial sites in the Lake Erie basin show that these improvements have continued as smaller sources are providing treatment and larger sources are achieving better control. For larger plants, compliance on a monthly basis is approaching 100%. Because of this, further point source reductions cannot exceed about 50 tonnes per year unless a lower phosphorus limit is established. © 1993, International Association for Great Lakes Research. All rights reserved.