Methods for Deriving Pesticide Aquatic Life Criteria - Reviews of Environmental Contamination and Toxicology - page 20

1 Introduction

The mission of California's nine Regional Water Quality Control Boards (RWQCB)
is “to develop and enforce water quality objectives and implement plans which will
best protect the beneficial uses of the State's waters, recognizing local differences in
climate, topography, geology and hydrology” (California SWRCB 2005). To accomplish
that mission, each RWQCB is responsible for development of a “basin plan” for its
hydrologic area. The “Water Quality Control Plan (Basin Plan) for the Sacramento
River and San Joaquin River Basins” (CVRWQCB 2004) contains the following
excerpts regarding toxic substances in general, and pesticides in particular:
…waters shall be maintained free of toxic substances in concentrations that produce detri-
mental physiological responses in human, plant, animal, or aquatic life.
No individual pesticide or combinations of pesticides shall be present in concentrations
that adversely affect beneficial uses.
Discharges shall not result in pesticide concentrations in bottom sediments or aquatic life
that adversely affect beneficial uses.
Pesticide concentrations shall not exceed the lowest levels technically and economically
achievable.

Development of specific numeric criteria for more pesticides would provide
clear goals for permitting and Total Maximum Daily Load (TMDL) programs. This
chapter is part of a larger project to develop a new aquatic life criteria methodology
for pesticides. The intent of this methodology is to establish, from available toxicity
data, a concentration unlikely to produce detrimental physiological effects in
aquatic species. The Central Valley RWQCB requested a literature review to define
the following: (1) criteria derivation methodologies currently in use, or proposed
for use, throughout the world; (2) original studies supporting the methodologies;
(3) proposed modifications of existing methodologies; and (4) relevant and recent
research in ecotoxicology and risk assessment. Four documents were found that
provide a good overview of the latest scientific thinking in the field of water quality
criteria derivation. First, is a topic, Reevaluation of the State of the Science for
Water-Quality Criteria Development (Reilly et al. 2003), which is a report of con-
clusions reached by participants in a Society of Environmental Toxicology and
Chemistry (SETAC) Pellston workshop. Second, is the “Draft Report on Summary
of Proposed Revisions to the Aquatic Life Criteria Guidelines” (USEPA 2002a).
Third, is a report from the United Kingdom (UK) Environment Agency called
“Derivation and Expression of Water Quality Standards, Opportunities and
Constraints in Adopting Risk-Based Approaches in EQS Setting” (EQS: environ-
mental quality standard; Whitehouse et al. 2004). The final document is a report
from the Fraunhofer-Institute of Molecular Biology and Applied Ecology, prepared
on behalf of the European Commission (EC), called “Towards the Derivation of
Quality Standards for Priority Substances in the Context of the Water Framework
Directive” (Lepper 2002). The information in these four reports, as well as conver-
sations with state and federal regulators (Karkoski 2005, personal communication;
Denton 2005, personal communication), were used to construct Table 1, which is a
list of components to consider when evaluating and developing aquatic life water
quality criteria derivation methodology.