WSP04023

• File Number: 8272.600.60
• Description: Colorado River Basin Salinity Control Program - Basin Member State Info - Utah
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 7/1/1990
• Title: Upper Colorado River Basin Rangeland Salinity Control Project
• Water Supply Pro - Doc Type: Report/Study

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entire mass of sediment and salt being issued into the main
channels and then into the Colorado River; this sediment slug
could result in many years worth of sediment and salt being
yielded in a single event, which could cause significant
environmental damage to endangered fish species, the Colorado
River fishery and potentially destabilize the downstream riparian
habitat.

The construction of debris basins within the Mancos Shale
geologic rock unit represents a potentially significant
environmental risk and would at best be a maintenance intensive
measure. Debris basin construction in the Mancos Shale rock unit
is not recommended because of the construction costs to build a
safe structure in a high-risk geologic hazard construction
environment, because of the high operation and maintenance costs
and because of the significant environmental hazards involved in
an embankment failure.

SEDIMENT AND SALT YIELD SUMMARY: Sediment and salt yield data
for each individual geomorphic unit are given in Appendix V,
pages 9 and 10. Sediment and salt yield data and calculations
for the proposed targeted land treatment acreage are given in
Appendix V, page 11. Comparison of natural (geologic) and human
accelerated sediment and salt yield data are given in Appendix v,
pages 12. Proposed treatment impact and target effect
calculations are given in Appendix V, page 13.

The land treatment target effect for the watershed is 7%. That
means treatment of 7% of the acreage of the watershed could
result in controlling 100% of the human-accelerated sediment and
salt yield problems. The proposed treatment could result in the
control of an estimated 15,147 acre-feet or 45,440 tons of
sediment and 3653 tons of salt.

Proposed land treatment measures in geomorphic units 1 and 2
could control 79% of the human-accelerated SEDIMENT yield
problems.

Proposed land treatment measures on geomorphic unit 2 could
control 84% of the human-accelerated SALT yield problems.

CONCLUSIONS; During this evaluation the following data and
studies were made:

_ sedimentation and salt yield of the watershed was modelled;

_ the source area of natural resource problems was targeted;

_ rangeland conditions were evaluated in a watershed setting;

_ reconnaissance hydrologic modeling of the watershed was
completed;

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