System theory formulation of site-specific water quality standards and protocols

Habitat variability makes site-specific considerations a necessity in the specification of water quality standards. The U.S. Environmental Protection Agency (EPA) has recognized this in its development of procedures for site-specific modification of national standards. These procedures involves translation of laboratory toxicology data into field situations where such data are often poor predictors of biotoxicity. The whole problem is poorly specified.This paper formulates a system theory approach to better specification of the problems associated with setting water quality standards. A state space model of the general environmental protection problem is presented: Find a set of diagnostic variables whose maintenance within specifiable limits (standards) is both necessary and sufficient to protect all variables of a subject ecosystem. The program for this comprises a site-specific protocol.Stages in such a protocol include (1) choice of diagnostic variables, (2) establishment of necessity and sufficiency for these variables, and (3) determination of standards through (4) toxicity testing. Problems associated with the latter include (a) spatiotemporal variability, system (b) linearity-nonlinearity, and (c) stationarity-nonstationarity, and (d) monitoring for: baseline information, impact detection, determining compliance, establishing causality and making predictions. Each of these problems is structured in terms of the state space model. Then, current procedures of the EPA site-specific methodology are reviewed, and a set of recommendations proposed for their improvement using the system theory formulation to guide further developments.