Re-segmentation of Oregon’s Assessed Waters for Inclusion in the U.S. Environmental Protection Agency’s National Assessment Database

Abstract

Re-segmentation of Oregon’s Assessed Waters for Inclusion in the U.S. Environmental Protection Agency’s National Assessment Database ABSTRACT The Oregon Department of Environmental Quality (ODEQ) is the state agency responsible for protecting Oregon's surface waters and for developing the state’s water quality standards. As required by section 305(b) of the Clean Water Act, ODEQ has established designated uses and is responsible for monitoring and assessing the quality of waters of the state. Oregon’s assessment methodology is designed to look at individual parameters, or contaminants, and based on the assessment conclusion to determine how to assign the assessment unit identifier. Oregon’s water quality standards are written in such a manner that they can include overlapping parameters, seasonal standards, and temperature standards (ODEQ, 2008). The overlapping nature of the stream segment leads to an over estimation of the number of miles of impaired waters. Because of the over estimation, Oregon appears to have more miles of impaired waters in the national 305(b) report than in actuality. The purpose of my master’s project is to examine Oregon’s methodology for assigning stream segment identifier numbers (IDs) and then develop a method using GIS tools to re-segment the IDs to align with the national standards that avoid duplication. This will eliminate the over estimation problem and thus the data will more accurately reflect the number of miles of impaired waters in Oregon.