Final Environmental Impact Statement Volume II Appendix K, Part 2

• Description: related to the Platte River Endangered Species Partnership ‎(aka Platte River Recovery Implementation Program or PRRIP)‎
• State: NE
• Basin: North Platte
• Date: 7/1/1998
• Author: Federal Energy Regulatory Commission ‎(FERC)‎ Office of Hydropower Licensing
• Title: Final Environmental Impact Statement ‎(EIS)‎ - Volume II, Appendix K, Part 2 - Kingsley Dam ‎(FERC Project No. 1417)‎ and North Platte/Keystone Dam ‎(FERC Project No. 1835)‎ Projects, Nebraska, FERC/FEIS-0063
• Water Supply Pro - Doc Type: EIS

COMMENTS OF U.S. ENVIRONMENTAL PROTECTION AGENCY
EPA -10 flows at Grand Island for the Modified Nebraska Plan. All other
(cunt.) values would be unchanged by this CWA requirement.)
Instream Flows at Grand Island to meet CWA requirements:
Pref. Alt. CWA
Mod. Neb Plan Required
Mean Daily Target Flow
Reservoir May 11 to Sep 15 May it to Sep 15
Storage
>1.550 MAP 800 cfs 900 cfs *
>1.400 MAP 800 cfs 900 cfs *
>1.300 MAP 800 cfs 900 cfs *
>1.100 MAF1 400 cfs 900 cfs *
>.900 MAP 0 900 cfs *
<.900 MAP 0 400 cfs **
U* - Needed to meet CWA requirements based on the
diminishing flow analysis (Zander, July 1994)
** - Needed to meet CWA. EPA recommends that sufficient
flow be maintained at all times to allow connection of
isolated pools within the main channel. During periods of
low reservoir storage below 0.900 MAP, which could occur 10
percent of the time, lethal temperatures will result with
zero target flows as proposed. Intense stress to aquatic
systems results from isolation in pools where competitive
conditions result in risk to species survival. Maintaining
a minimum flow to connect these pools is essential at all
times.
1.100 MAP of storage has a 75 percent exceedence level
for September and can be expected to occur once every
four years.
2 0.900 MAP of storage has a 90 percent exceedence level
for September and can be expected to occur once in
every ten years.
EPA considers 900 cfs to be the minimum flow needed to fully
protect the designated aquatic life use for the Platte River. In
those relatively infrequent situations where the storage pool
level falls below 0.9 MAP, EPA recognizes a special condition of
water shortage exists which requires an equitable sharing of
those shortages among the competing water uses. Under these
special conditions of shortage, the minimum river flow may be
allowed to fall to 400 cfs. This is, however, a flow at which
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RESPONSES TO U.S. ENVIRONMENTAL PROTECTION AGENCY