Use of Biological Indicators in TMDL Assessment and Implementation

Abstract

Biological indicators are used, in part, to assess the level of water quality with respect to this general standard. Under EPA's Total Maximum Daily Load (TMDL) program, impaired waters based on a biological assessment require an additional step compared with non-biological TMDLs. In non-biological TMDLs, the "pollutant" is typically the parameter being monitored, with a direct link to the impairment. In biological TMDLs, cause and effect must first be established between one or more pollutants and the impacted biological community. This article presents examples of approaches taken in different states to monitor and assess the biological health of our streams based on varying combinations of algal, macroinvertebrate, and fish communities. While fish are the ultimate integrator of lower ecological organisms, their occurrence and abundance has been greatly manipulated by humankind. Periphytic algae are perhaps the fastest responding biological population and can be used for some pollutant-specific diagnoses, but most states lack the expertise required for detailed taxonomic classification. Macroinvertebrates, the most commonly monitored biological community, are abundant in most streams, but most metrics are not diagnostic of specific stressors. Within the TMDL framework, issues are discussed related to setting TMDL targets, linking biological impairments with pollutants, and defining biological target endpoints. Although surrogate measures are often used for setting TMDL target loads, biological recovery is measured against biological endpoints. The use of biological indicators for assessment and development of biological TMDLs can be improved through modeling procedures that better define cause-and-effect relationships, through a better understanding of the limits of restoration, and through a more unified national policy that focuses on restoration.

A novel quantification method for stream-inhabiting, non-diatom benthic algae, and its application in bioassessment

“…The shortcomings of existing quantification methods for benthic non-diatom algae have probably contributed to the frequency with which they are excluded from periphyton bioassessment (STAR; Yagow et al, 2006). As a result, important aspects of the primary producer community may be missed and our knowledge about ecosystem structure and functioning may be affected (Bortolus, 2008).…”

Effects of geomorphology, habitat, and spatial location on fish assemblages in a watershed in Ohio, USA

“…In most states, water chemistry monitoring is conducted to support established water quality criteria and identify priority pollutants; however, chemical monitoring alone cannot ensure that all pollutants and interactions among them are meeting water quality goals (Yagow et al 2006). Ohio is one of the few states to have aquatic use requirements for lotic systems and to incorporate biological monitoring, or bioassessment, into its water quality standards.…”

Landscape Models for Simulating Water Quality at Point, Field, and Watershed Scales

“…A recent ASABE effort described by Muñoz-Carpena et al (2006) resulted in a series of publications addressing TMDLs. TMDLs often require watershedlevel modeling; hence, several TMDL-related publications include relevant watershed modeling discussions (e.g., Benham et al, 2006;Borah et al, 2006;Vellidis et al, 2006;Yagow et al, 2006).…”