The many years of work by Baykeeper Joe Payne and the Friends of Casco Bay are appreciated. In the Dec. 7 Bill Nemitz column, “Keeper’s quiet power leaves Casco Bay better, but still at risk,” Payne states, “Lately I’ve taken to saying nitrogen is going to be the death of us.”

I support this statement about nitrogen pollution from the watersheds of Casco Bay. I would like to add to Payne’s warning this statement by coastal scientists from around Narragansett Bay, in a 2004 University of Rhode Island report: “Nothing is more fundamental to the functioning of an estuary than the quantity and timing of freshwater delivery.”

The Nemitz column speaks of dead zones in the Presumpscot estuary. Studies from other states and countries cite similar dead zones due to reduced freshwater flows, which eliminate nature’s means of reducing nitrogen concentrations.

From May through October 1992, the Maine Department of Environmental Protection reduced by half the historic average monthly flows of the Presumpscot River during years of normal or below-normal precipitation.

The unnatural inflows that are now imposed upon the estuary contribute to a changed timing of nutrient delivery, increased pollution concentrations and harmful changes in the location of the physical and chemical forces of the colliding saltwater and freshwater.

The freshwater inflow reductions to Casco Bay are not minor and should be a priority for scientific study on how it affects the marine ecosystems and multiplies the impacts of sewage plant releases into the estuary. Protecting these coastal assets is crucial, as healthy near-shore coastal regions provide economic and environmental goods and services of about $9,000 per acre to our economy each year.

Roger Wheeler