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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actually rehabilitated with sediment and vegetation.

BADLAND DEBRIS BASIN: The BLM has constructed debris basins in
the badland unit of Sagers Wash Subwatershed. These basins are
currently trapping salt-laden sediment. The purpose of these
basins is to trap salt and sediment before it enters the Colorado
River. These debris basins are an attempt to control salt on
rangeland from a geologic background source. As noted in the
Unit 4 - Badlands geomorphic section of this report, sediment and
salt that yield from Sagers Wash Subwatershed are deposited in
Sagers Flat floodplain. Sagers Flat acts as a detention basin
for the badlands sediment issuing from the upper area of Sagers
Wash Subwatershed. These specific debris basins are actually
controlling approximately 50% of the sediment that is trapped
behind them. The other 50% would be trapped naturally in Sagers
Flat. Furthermore, the sediment yielded from Sagers Flat is
subject to an estimated 80% delivery ratio. Therefore, these
debris basins are functioning to control 40% of the salt and
sediment trapped in them; the other 60% would be controlled by
Sagers Flat and the floodplain of the lower watershed.

It should be noted that Pinto Wash Subwatershed also flows
through Sagers Flat. Therefore, any debris basins planned for
this area would have the same estimated 40% efficiency as those
in sagers Wash Subwatershed.

The planning and construction of debris basins in the Mancos
Shale soils is subject to the following engineering geologic
hazards:
- the construction material is of a highly erosive nature
(ML-CL), (ML) , and dispersive (CH);

- the construction, foundation, abutment, reservoir bottom
and surrounding materials are subject to rapid solutioning of the
salts in them and the consequent differential collapse of these
materials (which could cause the failure of the structures);

these structures have a limited life as regards storage
volume and will rapidly fill up with salt-laden sediment,
therefore the operation and maintenance of these structures is of
high frequency and significant cost;

- failure to clean out filled sediment pools could result in
storm flows over-topping the embankment;

- failure of the embankment can occur due to over-topping by
flows from an intense storm event, erosion of the embankment by
piping through differential settlement cracks or over-topping due
to small frequent storm flows imparting a full or nearly full
sediment pool;

- failure of the embankment for any reason can result in the

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