9390

• UCREFRP Catalog Number: 9390
• Author: Webb, R. H., T. S. Melis and R. A. Valdez.
• Title: Observations of Environmental Change in Grand Canyon, Arizona.
• USFW Year: 2002.
• USFW - Doc Type: 02-4080,
• Copyright Material: NO

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Figure 4. Deer Creek Falls (mile 136.1-R) (continued).

C (left). July 1, 1972. Because of flood control operations of Glen Canyon Dam, riparian vegetation has increased
along the river. This lush growth of native and non-native species is typical of conditions in 1972 in Grand Canyon
(Matches A, Raymond M. Turner, Stake 692).

D (right). November 3,2001. A flood in the summer of 2001 stripped much of the riparian vegetation out of the
mouth of Deer Creek. In the 1980s and 1990s, floods of this magnitude have occurred every 2-4 years. Again, the
rocks have been removed from the debris fan and cobbles cover its surface. Debris fans are aggrading throughout
Grand Canyon, and the fan at the mouth of Deer Creek is no exception (Matches B, Tom Brownold, Stake 2985).

One of the most perceptive observations carne
from Reilly. He mentioned changes caused by the 1955
debris flow at Lava Falls, such as fewer holes and
smoothing of the rapid as the spaces behind the large
boulders were filled with smaller ones. Sediment
eroded from the fan filled in much of the eddy
downstream to the Warm Springs, making the lining
operation easier.

Sand Bars

Our work with repeat photography, particularly
with the Stanton photography of 1889-1890, suggests
that sand-bar erosion was severe and decreases with
distance downstream from Glen Canyon Darn (Schmidt
and Graf, 1990; Schmidt and others, 1995; Webb,
1996). We wanted the Old Timers' opinion on that
conclusion. Most of the Old Timers lamented the
current status of sand bars in Grand Canyon,
particularly in Marble Canyon (miles 0 to 61); they
often pointed to sand bars and noted how small they

SPECIFIC CHANGES OBSERVED IN GRAND CANYON 15