Evaluation of Different Approaches for Controlling Phosphorus Pollution in the Maumee River Watershed

Abstract

There is a growing consensus among scientists and natural resource managers that conservation efforts addressing nonpoint source pollution are most effective when coordinated at a watershed scale. In light of this understanding, the question is how to mobilize effective conservation strategies at the watershed scale in order to ensure desired water quality. With public resources limited, much of this question can be understood as a tension between seeking to put in place those actions that will assure the largest improvements in water quality while striving for the lowest costs to land owners, citizens, and agencies. The Maumee River watershed, whose 8,316 square mile area is over 70% in agricultural land cover, presents an interesting and timely setting for tackling this challenge.1 The Maumee’s tri-state river watershed, spanning OH, IN, and MI, drains into the Western Lake Erie Basin and carries with it an excess load of dissolved reactive phosphorus (DRP), a nutrient that contributes significantly to the occurrence of harmful algal blooms (HABs). While HABs have been an increasing concern over the last decade, they came to the forefront of national news when in August 2014 the City of Toledo was forced to shut off its drinking water supply sourced from Western Lake Erie to approximately 500,000 metropolitan area residents due to microcystin contamination, a toxin produced by a HAB in Western Lake Erie.2 This report identifies a wide spectrum of conservation practices and policy approaches for reducing DRP at the watershed scale, including both voluntary and regulatory approaches. These are combined with model analysis of the physical watershed’s landscape and an independently designed cost effectiveness analysis in order to create marginal cost of abatement curves that define a suite of possible watershed scale management scenarios structured to achieve optimum improvements to water quality.