chapter i\/ 
Refinements to Procedures for 
Assessing Chesapeake Bay 
Water Clarity and SAV Criteria 
BACKGROUND 
With the publication of the Ambient Water Quality Criteria for Dissolved Oxygen, 
Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries 
(Regional Criteria Guidance) (U.S. EPA 2003a) and the Technical Support Docu¬ 
ment for Identification of Chesapeake Bay Designated Uses and Attainability 
(Technical Support Document) (U.S. EPA 2003b), the jurisdictions were provided 
with extensive guidance for how to determine attainment of the shallow-water bay 
grass designated use. Additional guidance addressing 1) water clarity criteria appli¬ 
cation periods, 2) SAV restoration acreage to shallow-water habitat acreage ratios, 3) 
SAV restoration goal acreages and 4) determining attainment of shallow-water bay 
grass use was further provided by Ambient Water Quality Criteria for Dissolved 
Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal 
Tributaries - 2004 Addendum (U.S. EPA 2004). Additional details of water clarity 
criteria and SAV restoration acreage attainment assessments were published in the 
Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and 
Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries - 2007 Addendum 
(U.S. EPA 2007). 
Since publication of the U.S. EPA 2007 Addendum, the following specific revisions 
have been agreed upon by the Chesapeake Bay Program partners: 
• Revision of the water clarity acres assessment methodology; 
• Clarification on the method for calculation of water clarity acres; 
• Clarification on the statistical model involved in converting turbidity to K d ; and 
• Development of the interpolation approach. 
Water clarity criteria and SAV restoration acreages are used to define attainment of 
the shallow-water bay grass designated use in Chesapeake Bay, its tidal tributaries 
chapter iv 
Refinements to Procedures for Assessing Chesapeake Bay Water Clarity and SAV Criteria 
