clean and clear

ST. Albans Bay Studies

Phosphorus has accumulated in the sediments of St. Albans Bay from decades of excessive loading from point and nonpoint sources in the watershed. This sediment store of phosphorus is now recycling back into the water and is continuing to feed algae blooms in the bay in a process called “internal loading.”

The phosphorus cycle in St. Albans Bay, showing internal phosphorus loading from the bay’s sediments.

A sediment core study in St. Albans Bay was funded by Clean and Clear and conducted by the University of Vermont Department of Geology during 2004. This study found that a substantial reservoir of phosphorus remains in the sediments of St. Albans Bay and that this stored phosphorus has the potential to recycle back into the water of the bay for a long period of time into the future.

Given these findings, the Agency of Natural Resources initiated a feasibility study for the control of internal phosphorus loading in St. Albans Bay using Clean and Clear funds appropriated in FY 2007. The feasibility study will be conducted in two phases. The purpose of the first phase is to compare treatment options for the control of internal phosphorus loading in St. Albans Bay as to their feasibility, likelihood of success, environmental impacts, and cost. A second phase of the study will provide a detailed treatment design for the chosen alternative and supply most of the information needed to support the environmental permitting process, if a decision is made in the future to proceed with a treatment. The Agency of Natural Resources is being assisted on the study by a Project Advisory Committee composed of Lake Champlain Basin scientists, resource managers, and area citizens. A final report on the Phase 1 findings and recommendations (PDF 570KB) was submitted by the lake management consultants at ENSR Corp. in June 2007.

ENSR recommended a program that includes dosing of incoming water from Stevens and Jewett Brooks (at Black Bridge) with aluminum compounds as an interim measure while watershed phosphorus sources are being addressed. Treatment of sediments of the inner bay using aluminum compounds was also recommended after external loads are reduced either by watershed management or by establishment of tributary dosing stations. A Phase 2 analysis would be needed to better define the project and more fully evaluate the environmental impacts.