Document: NRC Regulatory Guide
Document ID: e5306f4f-dc8c-4f60-a71c-af7ad4080384
Document Type: regulatory_guide
Title: Aquatic Environmental Studies for Nuclear Power Stations + HISTORY - HISTORY 12/2014 – DG-4023 -Proposed New Guide
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML1318/ML13186A085.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.24
CFR Part: 
CFR Title: 

Content:
ecessary to determine the types of aquatic environmental impact analyses appropriate to an NRC decision or action. Analysts need to consult recent scientific literature and natural resource regulatory agencies for direction in planning impact analyses. This guide cannot anticipate all categories of aquatic environmental impact analyses potentially appropriate to NRC decisions or actions. However, the following are generally considered “good” practices: • use best available baseline data, whether collected specifically for the subject activity or available from published sources, agency files, communication with regional experts, or other credible sources • support findings clearly with data and logic • use information that is as quantitative as practicable • implement methodologies or models that are widely accepted by the scientific community, natural resource agencies, and regulatory agencies • avoid experimental or unproven methodologies, assumptions, or models • avoid unsupported speculation or opinion. DG-4023, Page 20 Habitat Modification Analyses Intake and discharge structure installation, pipeline installation, dredging, barge slip installation, impervious surface creation, and other site-preparation and building activities result in the modification, conversion, fragmentation, or loss of aquatic habitats. Operational activities, such as water withdrawal, thermal discharge, and discharge of chemical constituents, also can alter aquatic habitats through processes such as scouring and degradation of water quality. For aquatic habitats, modifications include, but are not limited to, altered current or upwelling patterns, changes in salinity gradients, scouring, temperature changes, eutrophication, discharge of contaminants (e.g., biocides), and altered sediment transport patterns. For habitat modification analysis one needs to quantify habitat modifications, conversions, fragmentation, and losses by mapping and analyzing the following: • the