In 1990, Ohio EPA initiated an organized, sequential approach to monitoring and assessment termed the five-year basin approach. One of the principal objectives of this approach is to better coordinate the collection of ambient stream and river monitoring data so that information and reports are available in time to support water quality management activities such as the reissuance of wastewater discharge (NPDES) permits, development of watershed Total Maximum Daily Load (TMDL) documents, and periodic revision of the Ohio Water Quality Standards (WQS). Initially, the state was divided into 25 hydrologic units that represented aggregations of subbasins within the 23 major river basins previously delineated by Ohio EPA for the Planning and Engineering Data Management System for Ohio (PEMSO) system. The 25 hydrologic units are roughly distributed equally among the five Ohio EPA districts. Each year, monitoring takes place within five of the areas, one in each of the five Ohio EPA districts, with an aggregate total of 400-500 sampling locations. Thus, five years is required to complete the cycle of monitoring within each of the 25 hydrologic areas.
Further refinement of the five-year basin design occurred in the early 2000s in response to Ohio EPA's decision to embark on a progressive watershed-based monitoring, assessment and reporting approach to facilitate the collection of data to support development of TMDLs impairing beneficial uses using the 12-Step TMDL Process (Ohio EPA, 1999). To this end, Ohio EPA adopted as basic watershed assessment units the U.S. Geological Survey 11-digit Hydrologic Unit (HUC-11); there are 331 delineated within Ohio. The HUC-11 assessment units were thought to be of practical size for development, management and implementation of effective TMDLs and, as such, served as the basic biosurvey design for this high-priority program activity through 2007. However, in practice, TMDLs were effectively being implemented with projects operating at the U.S. Geological Survey 12-digit Hydrologic Unit (HUC-12) scale. Thus, beginning with the 2008 survey year and as reported in the 2010 Integrated Water Quality Monitoring and Assessment Report, 1,538 HUC-12 watershed assessment units (WAUs) became the primary reporting unit for watershed survey monitoring and assessment and TMDL development and implementation.
The HUC-12 WAU scale is used to categorize and assess stream and river sites draining watersheds up to 500 square miles. For Ohio's largest rivers greater than 500 square miles, large river assessment units (LRAUs) were developed on which to report independently since they are unique in their importance and cannot be readily included and effectively assessed in small HUC-12 watersheds. At this size, rivers generally are impacted more by the character of and activity in the accumulated drainage area and less by what is happening adjacent to the channel (i.e., on the stream bank) or in the immediate adjacent landscape. Currently, 38 LRAUs have been established for the 23 largest rivers in Ohio.
Ohio EPA's approach to surface water monitoring and management via the five-year basin approach essentially serves as an environmental feedback process taking "cues" from environmental indicators to effect needed changes or adjustments within water quality management. This hierarchy is essentially in place within the technical support document (TSD) process and represents, from a technical assessment and indicators framework standpoint, a watershed approach. The environmental indicators used in this process are categorized as stressor, exposure and response indicators.
- Stressor indicators generally include activities that impact but may or may not degrade the environment. This includes point and nonpoint source loadings, land use changes and other broad-scale influences that generally result from anthropogenic activities.
- Exposure indicators include chemical-specific, whole effluent toxicity, tissue residues and biomarkers, each of which suggest or provide evidence of biological exposure to stressor agents.
- Response indicators include the direct measures of the status of use designations. For aquatic life uses, the community and population response parameters that are represented by the biological indices that comprise Ohio EPA’s biological criteria are the principal response indicators. For human body contact uses (e.g., primary contact recreation), fecal bacteria (e.g., E. coli, fecal coliforms) are the principal response indicators.
The key to having a successful watershed approach is in using the different types of indicators within the roles that are the most appropriate for each. The inappropriate use of stressor and exposure indicators as substitutes for response indicators is at the root of the national problem of widely divergent 305(b) statistics reported between the states. This issue is discussed in the 1994 Ohio Water Resource Inventory (Ohio EPA 1995).
An assessment of the impact of multiple sources on the receiving waters of a watershed includes an evaluation of the available chemical/physical (water column, effluent, sediment, flows), biological (fish and macroinvertebrate assemblages), and habitat data that have been collected by Ohio EPA pursuant to the five-year basin approach. Other data evaluated includes, but is not limited to, NPDES permittee self-monitoring data, effluent and mixing zone bioassays conducted by Ohio EPA, the permittee, or U.S. EPA, spills data compiled by Ohio EPA, and fish kill information from the Ohio Division of Wildlife.
The integration of this information into a report for each study area is accomplished via the TSD process. Besides reporting on status and trends for the applicable designated uses, the TSD also identifies and describes causal associations of use impairments with the predominant causes and sources of impairment. The completion of this process enables the structured use of the output from the TSD (i.e., the assessment of water bodies) to support virtually any Ohio EPA program where surface water quality is a concern.
The systematic monitoring and assessment of Ohio surface waters via the five-year basin approach since 1990, and overall since 1980, has produced a comprehensive database that can be used to address issues of statewide and program importance. Ohio EPA periodically produces technical bulletins to provide an in-depth analysis of specific issues ranging from the validation of specific water quality criteria to process descriptions for tools such as the biological criteria. These analyses would not be possible without the systematic baseline monitoring and assessment which are an aggregate result of the five-year basin approach.
U.S. EPA has developed a site on Biological Indicators of Watershed Health. The following paragraph is a July 1999 review from the Internet Scout Report.
This recently launched site on biological indicators, from the Environmental Protection Agency, is a gem, offering basic yet critical information on the what, where, why, and how of biological indicators. Presented in straightforward language, the site sets out to educate viewers about the importance of biological indicators -- those organisms that, because of their sensitivity to changes in the environment, "can provide accurate information about the health of a specific river, stream, lake, wetland, or estuary." The site is organized into seven main sections: Why use Indicators?, Key Concepts, Learn About State Programs, Biocriteria Resources, Fish as Indicators, Invertebrates as Indicators, and Periphyton as Indicators. In each section, a series of brief statements (with accompanying color photographs) leads the viewer through the logic, techniques, and methods used to assess watershed health. A collection of links rounds out the site.
From The Scout Report for Science & Engineering, Copyright Internet Scout Project 1994-1999. http://scout.cs.wisc.edu/
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