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

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COMMENTS OF U.S. ENVIRONMENTAL PROTECTION AGENCY
of these assumptions, these ground water models overestimate
reduction in ground water mounds and reduction in stream return
flows if agriculture seepage is reduced.
We believe these modeling efforts do not properly evaluate
the effect of ground water flow beneath the Platte River. The
modeling assumption of combining the Platte River valley fill
aquifer with the underlying and much more aerially extensive
Ogallala aquifer is not appropriate. The assumption that the
Platte River is a boundary and no flow exists is only valid for
the thin valley fill aquifer in the Platte River valley. It
would be more appropriate to model the two aquifers as separate,
but hydraulically connected, using appropriate vertical
gradients. We have discussed this matter with the USGS staff
investigating Platte River water quality for the National Ambient
Water Quality Assessment (NAWQA) program in Lawrence, Kansas.
The USGS staff also believes there are two distinct ground water
systems near the Platte River -- the valley fill aquifer and the
Ogallala. The USGS NAWQA effort will include ground water flow
analysis using tritium tracers to assess these conditions
beginning in September 1994.
By combining the valley fill aquifer with the Ogallala
aquifer there is a failure to consider the effect of ground water
underflow in the deeper portions of the Ogallala. The saturated
thickness of the Ogallala aquifer is up to 200 feet in this area.
Under such circumstances, a significant amount of ground water in
the lower part of the aquifer will move with the regional flow
system towards the southeast. Most of the districts, irrigation
water is seeping into the Ogallala, not the valley fill aquifer.
Thus the modeling efforts are inaccurate because a significant
portion of the ground water in the Ogallala will move within the
regional flow system and discharge to the southeast away from the
Platte River.
In addition, requiring water conservation as a license
condition would be consistent with the intent of the recently
signed three state /DOI agreement. On June 10, 1994, the states
of Nebraska, Wyoming, and Colorado and DOI signed a Memorandum of
Agreement (MOA) for the Platte River Basin Recovery
Implementation Plan (RIP). While it is not yet clear how this
MOA might be applied, recent determinations by FWS for special
permit renewals in the South Platte River basin by the Forest
Service in Colorado give an indication of what is needed to
implement the Platte River RIP (as stated in the seven draft
biological opinions dealing with reissuance of special permits
for reservoirs on the Roosevelt National Forest, Fish and
Wildlife Service to the Forest Service, October 19, 1993).
A requirement likely to be placed upon Nebraska as a result
of the three state /DOI MOA would be to provide new water to help
restore basin depletions in addition to the redistribution of
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RESPONSES TO U.S. ENVIRONMENTAL PROTECTION AGENCY