Special Issue "Nutrient Water Quality Changes in Headwaters of the Laurentian Great Lakes" in the journal Water
The central and western basin of Lake Erie, and other nearshore areas of the lower Laurentian Great Lakes, are experiencing a resurgence in eutrophication and associated symptoms of impaired water quality similarly observed in the 1960s. Some of the ecosystem health implications of these eutrophic episodes include the occurrence of nuisance and potentially harmful algal blooms, anoxia and fish death.
Following the implementation of the 1972 Great Lakes Water Quality Agreement, the Great Lakes, particularly Lake Erie, exhibited signs of restored ecosystem health and function, primarily due to phosphorus control from municipal sewage. Nearly 50 years later, in the present day, eutrophic conditions and associated symptoms have returned and persist, despite decades of municipal phosphorus loading reduction efforts.
A comprehensive understanding of this seeming paradox is not yet fully established. It is possible that in the intervening period, important changes to the timing and forms of nutrients delivered to lakes have occurred, particularly from small headwaters that are dominated by non-point sources of nutrients, including urban and agricultural lands. There exists a critical research need to explore how land use and management have changed over time to better understand the potential linkages to eutrophication, and ultimately, how management actions in these watersheds may improve nutrient loading reductions in the Great Lakes. Headwaters present the best opportunity to observe particular interactions of land use, land management, and environmental factors, and to infer their effects on nutrient loadings to downstream systems.
This Special Issue will focus on nutrient loading information from headwater agricultural sub-watersheds. We will highlight work that characterizes changes in nutrient loading over multiple temporal scales and the conditions that impact nutrient loading, such as land use, site characteristics and hydrology. The papers will present novel insights on regional nutrient modelling, nutrient impact forecasting and policy implications of the best management practices and future change. We are especially interested in featuring papers from both sides of the Canada-US border.