Endocrine-disrupting contaminants such as environmental estrogens have been found and studied in large lakes and streams and shown to exist at concentrations that have adverse effects on wildlife. However, very little is known about the sources and effects of environmental estrogens in small, shallow lakes. Preliminary data suggests that these compounds are present in shallow lakes and have an effect on the survival and reproduction of wildlife. Researchers at the University of St.
Minnesota supports over 14 million acres of cropland in grain production. Almost 600,000 tons of synthetic nitrogen fertilizers are needed annually to maintain productivity on this land, which requires the equivalent of 3,000,000 barrels of oil and costs farmers over $400 million dollars per year. This amount of fossil fuel use results in a significant amount of greenhouse gas emissions, while the absence of fossil energy resources in the state means that these synthetic nitrogen fertilizers must be imported into Minnesota from other states and overseas.