BOARD00503

• Board Meeting Date: 5/24/2004
• Description: WSP Section - Platte River Recovery Implementation Program Update. Draft Environmental Impact Statement and National Academy of Science Update.
• Board Meetings - Doc Type: Memo

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Endangered and Threatened Species of the Platte River

survival and recovery of piping plovers and least terns. Although both species use artificial
habitat (such as shoreline areas of Lake McConaughy and sandpits), the quality and availability
of sites are unpredictable from year to year. The committee further concluded that suitable
habitat for the whooping crane along the central Platte River is essential for its survival and
recovery because such alternatives as the Rainwater Basin and other, smaller rivers are used only
intermittently, are not dependable from one year to the next, and appear to be inferior to habitats
offered by the central Platte River.

9. Are the conclusions of the Department of the Interior about the interrelationship of sediment,
flow, vegetation, and chanlJel morphology in the central Platte River supported by the existing
science?

The committee concluded that DOl conclusions about the interrelationships among
sediment, flow, vegetation, and channel morphology in the central Platte River were supported
by scientific theory, engineering practice, and data available at the time of those decisions, By
the early 1990s, when DOl was react)ing its conclusions, the community of geomorphologists
concerned with dryland rivers had a general understanding of the role of fluctuating discharges in
arranging the land forms of the channel, and DOl included this understanding in its conclusions
about the river. In the early 1990s, engineering practice, combined with geomorphology and
hydrology, commonly used IFIM and PHABSIM to make predictions and recommendations for
flow patterns that shaped channels, and this resulted in adjustments in vegetation and habitat. In
fact, despite some criticisms, IFIM and PHABSIM are still widely used in the professional
community of river restorationists in 2004. In applying scientific theory and engineering
practice, the DOl agencies used the most current data and made additional measurements to
bolster the calculations and recommendations. Since the early I 990s, more data have become
available, and the USBR has conducted considerable cutting-edge research on a new model
(SEDVEG) that should update earlier calculations but is not yet in full operation (and was not
reviewed by this committee),
Sediment data are obtained by sampling sediment concentrations and multiplying the
concentrations by discharges and duration, For flow, gaging records on the Platte River are 50
years in duration or longer, and they are in greater density than on many American rivers; the
gages provide quality data on water discharge for the Platte River, Murphy and Randle (2003)
review the analyses and other sources of knowledge about the flows that provide a sound basis
for DOl decisions, In addition to the review by Murphy et aI. (2001) concerning vegetation,
several studies over the last 20 years have provided an explanation of vegetation dynamics that
the committee found to be correct and that is the basis of DO I decisions. Early work by USFWS
(198Ia) and Currier (1982) set the stage for an evolution of understanding of vegetation change
on the river that was later expanded by Johnson (1994). For channel morphology, there is a long
history of widely respected research to draw on, including early geomorphologic investigations
by Williams (1978) and Eschner et al. (1983), continuing with the reviews by Simons and
Associates (2000), and culminating in recent work by Murphy and Randle (2003).

10, What were the key information and data gaps identified in the review?

The committee reached its conclusions for the preceding nine questions with reasonable
confidence based on the scientific evidence available. However, the committee identified the

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