WSP04101

• File Number: 8080
• Description: Section D General Interstate Litigation - Rainbow Bridge Monitoring Program
• State: CO
• Basin: Statewide
• Date: 5/21/1964
• Author: DOI-BOR
• Title: Rainbow Bridge Monitoring Program - Reports 4 through 10
• Water Supply Pro - Doc Type: Report/Study

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physical change in the rock structure but do show the high' reservoir
line impressed on the canyon walls at maximum reservoir elevation
3674.93 which occurred on July 25, 1975.
5. Moisture Rock Samples - No additional data.
6. Rock Hechanics - No additional data.
7. Geologic Sections - No additional data.
The geological sections will be re-examined in the field when the next
minimum reservoir elevation occurs at which time maximum exposure of
rock will be observable. Erosion control points installed in the rock
walls along the geologic section under Rainbow Bridge will be surveyed
'duri ng thi s next survey.
8. Seismic Monitorin~
The USGS has finally procured the necessary equipment for the seismic
station and ~Iill install it in December 1975.
9. Ecology - Environmental Effect
Any ecological effects that might occur would be more noticeable
at ,minimum reservoir than at maximum reservoir elevation. Minor
vegetation growth submerged by the water is dying and a noticeable
. white water level coating composed of carbonate deposition and
byophritic plant growth is observable as the reservoir recedes.

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The environment is being moderately modified by human visitation and
mild forms of vandal i sm. Swinrni ng and di vi ng from the cl i ffs .
dislocation of gravel (cobbles and boulders) from the slopes is

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