2 
• Summary of findings, incidental take and recommended reasonable and prudent 
measures published in the Endangered Species Act required NOAA shortnose 
sturgeon biological opinion on the potential impacts and benefits from state adop¬ 
tion of the Regional Criteria Guidance into water quality standards (Chapter 4). 
• Guidance to the jurisdictions on when and where attainment of the instantaneous 
minimum, 1-day mean and 7-day mean dissolved oxygen criteria can be assessed 
using monthly mean water quality monitoring data (Chapter 5). 
• Guidance to the jurisdictions for deriving site-specific dissolved oxygen criteria 
and assessing criteria attainment of those tidal systems where naturally low 
dissolved oxygen concentrations are due to extensive adjacent tidal wetlands 
(Chapter 6). 
• Documentation of the methodology for delineating the upper and lower bound¬ 
aries of the pycnocline used in defining the vertical boundaries between 
open-water, deep-water and deep-channel designated uses (Chapter 7). 
• Updated guidance to the jurisdictions for potential combined application of the 
numerical water clarity criteria to shallow water habitats and submerged aquatic 
vegetation (SAV) restoration goal acreages for defining attainment of the shallow- 
water bay grass designated use (Chapter 8). 
• Guidance to the jurisdictions for determining where numerical chlorophyll a 
criteria should apply to local Chesapeake Bay and tidal tributary waters (Chapter 
9). 
Through publication by EPA as a formal addendum to the 2003 Chesapeake Bay 
Regional Criteria Guidance document, this document should be viewed by readers 
as supplemental chapters and appendices to the original published Regional Criteria 
Guidance document. The publication of future addendums by EPA is likely as 
continued scientific research and management application reveal new insights and 
knowledge to be incorporated into revisions of state water quality standards regula¬ 
tions in upcoming triennial reviews. 
chapter i 
Introduction 
