THE PONDS PROJECT - Sustainable Conservation

4. What minimum bypass flows and possible maximum rates of withdrawal are needed
for the project to facilitate migratory movements of anadromous salmonids
downstream from the diversion site?
National Marine Fisheries Service (NOAA Fisheries) recommended that these issues be addressed
because of the possible inadequacy of the default bypass flow recommendation (the stream’s longterm
median daily flow in February) in cases where more than 10% of the total volume of winter flow
is already appropriated. Our concerns are that streams in which a significant portion of winter flow is
already diverted or otherwise allocated can be theoretically reduced to the minimum level for
significant durations (flatlined) and that the default February median flow may not provide sufficient
flow for anadromous salmonid spawning and migration in small watersheds. The February median
flow is also generally insufficient as a channel maintenance flow. Our response and concerns are
consistent with Department of Fish & Game/NOAA Fisheries (2002), which recommends site specific
studies to address the above three issues when CFII values exceed 10% or when there is an
appreciable impairment of the hydrograph on projects with CFII between 5 and 10%.
In your March 8 phone call with Dr. Hearn, you requested additional guidance on the kinds of studies
and analysis that would be appropriate to address the above three issues in minor water right projects
where CFII exceeds 10%. Attachment A provides some suggested approaches for addressing these
issues. However, the described approaches are not a comprehensive listing of the only ways to
examine bypass flow needs to protect these important ecological processes. Applicants, their
consultants, or others may find other suitable methods for addressing these issues. We recommend
that study plans be developed in consultation with CDFG and NOAA Fisheries prior to
commencement of fieldwork in order to promote acceptance of the study methods and results. For
example, study area boundaries, lifestages of evaluation species, habitat suitability criteria, transect
locations, and field measurement procedures should be reviewed by these resource agencies prior to
field work. As appropriate, study sites or transects should be collaboratively identified in the field.
We appreciate this opportunity to help further your objective of conducting credible environmental
assessments for minor water development projects. If you have questions about this letter and
recommended study approaches, please contact Dr. William Hearn at (707) 575-6062.
Sincerely,
Original Signed by
Steven Edmondson
Habitat Manager
Northern California
Attachment
cc: R. Floerke, CDFG (Yountville)
P. Rutten, NOAA Fisheries
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