Joint Comments on Draft EPA-USGS Technical Report Jun 17, 2016 Comment Letters Agencies: U.S. Environmental Protection Agency and U.S. Geological Survey Subject: Docket: EPA-HQ-OW-2015-033 (Drat EPA-USGS Technical Report: Protecting Aquatic Life from Effects of Hydrological Alteration Other signatories: Northern California Water Association, San Luis & Delta-Mendota Water Authority, State Water Contractors Letter excerpt: The Technical Report, which presents a framework to quantify flow targets that incorporates EPA guidelines and concepts from contemporary environmental flow literature, declares that “The framework does not prescribe any particular analytical approach … but rather focuses on the process and information needed to evaluate relations between flow and aquatic life and to select numeric flow targets.” To accomplish this stated goal, the Technical Report describes a series of hypotheses regarding the potential environmental and biological benefits of new flow requirements. However, it fails to acknowledge the scientific uncertainty related to the biological and/or physical outcomes of regulating or re-regulating flow, particularly in highly degraded environments. The Technical Report promotes the concept of “natural” flow conditions, which has appeal in relatively untouched environments. In highly altered environments, however, there is significant uncertainty regarding how the environment will respond to new flow patterns. The Technical Report describes scientific information related to “natural” conditions, but does not address the complexity associated with defining “natural.” Is “natural” a timeframe before significant anthropogenic modification or a more recent era? This question is highly relevant to California’s Sacramento-San Joaquin Bay-Delta watershed as the physical environment has continued to undergo modification since the early-to-mid 1800s. Download joint comment letter
