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the proposed water clarity criteria would beneficially affect preferred habitat, 
spawning areas and food sources that the listed shortnose sturgeon depends. 
The EPA determined that the recommended chlorophyll a criteria would not likely 
adversely affect the listed species evaluated. Furthermore, the EPA determined that 
the recommended chlorophyll a criteria would beneficially affect preferred habitat, 
spawning habitat and food sources on which the listed species depends. 
The EPA determined that the collective application of dissolved oxygen criteria for 
the migratory fish spawning and nursery and open-water fish and shellfish desig¬ 
nated uses were fully protective of shortnose sturgeon survival and growth for all life 
stages based on the following: 
• The migratory spawning and nursery 6 mg liter -1 7-day mean and 5 mg instanta¬ 
neous minimum criteria will fully protect spawning shortnose sturgeon. The 
February 1 through May 31 application period for the migratory spawning and 
nursery criteria fully encompasses the mid-March through mid-May spawning 
season documented previously from the scientific peer-reviewed literature. 
• The individual components of the open-water criteria protect shortnose sturgeon 
growth (5 mg liter -1 30-day mean), larval recruitment (4 mg liter -1 7-day mean) 
and survival (3.2 mg liter -1 instantaneous minimum). A 4.3 mg liter -1 instanta¬ 
neous minimum criterion applies to open waters with temperatures above 29°C 
considered stressful to shortnose sturgeon. 
• The open-water criteria applied to tidal fresh waters include a 5.5 mg liter -1 
30-day mean criterion providing extra protection of shortnose sturgeon juveniles 
inhabiting tidal freshwater habitats. 
The EPA determined that adoption of the proposed dissolved oxygen criteria into 
Maryland, Virginia, Delaware and the District of Columbia’s state water quality stan¬ 
dards and their eventual attainment would beneficially affect shortnose sturgeon 
spawning, nursery, juvenile and adult habitats and food sources by driving wide¬ 
spread nutrient loading reduction actions leading to increased existing ambient 
dissolved oxygen concentrations. EPA stated that this determination was consistent 
with and pursuant to Endangered Species Act provisions that the responsible federal 
agency—EPA in this case—use its authority to further the purpose of protecting 
threatened and endangered species (see 16 U.S.C. § 1536(a)). EPA also stated that 
its determination was also consistent with the NOAA National Marine Fisheries 
Recovery Plan for shortnose sturgeon which recommends working cooperatively 
with states to promote increased state activities to promote best management prac¬ 
tices to reduce non-point sources (NOAA National Marine Fisheries Service 1998). 
The EPA determined that adoption, implementation and eventual full attainment of 
the states’ adopted dissolved oxygen water quality standards would result in signifi¬ 
cant improvements in dissolved oxygen concentrations throughout the tidal waters to 
levels last observed consistently more than four to five decades ago in Chesapeake 
Bay and its tidal tributaries. 
chapter iii 
Key Findings Published in the EPA ESA Shortnose Sturgeon Biological Evaluation 
