WSP09723

• File Number: 8271.300
• Description: Colorado River Basin Salinity Control Program - General Information and Publications-Reports
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1993
• Title: Greater Sagers Wash Watershed Management Plan
• Water Supply Pro - Doc Type: Report/Study

WATERSHED CONDITION ANALYSIS

o
o A selective management concept has been conceptually outlined by BLM's Soil, Water and Air
..;::.. program to categorize watershed units (hydrologic basins and sub-basins) as to the priority each
W deserves for investments in watershed treatments and improvements. This watershed condition
analysis concept (patterned after the selective management approach of BLM's range
management program) involves a thought process, data examination, and professional judgement
in order to defme the existing situation and to identify potentially achievable or deteriorated
situations.

The four selective management categories of watershed condition analysis are explained in BLM
Handbook-1740-1 (Renewable Resource Improvement and Treatments). Using this system, the
highest priority for action would be given to: I.) those watersheds where a high degree of
vulnerability presents a threat to a watershed currently in good condition, and 2.) watersheds
where the potential for response to treatment would effectively and efficiently lead to a
satisfactory watershed condition.

,

The watershed condition analysis for a BLM watershed undergoing comprehensive salinity
control planning in this instance is believed to be a frrst. The watershed condition class
(SATISFACTORY or UNSATISFACTORY) is detennined by the relationship between the
existing situation and a predetennined threshold level (ELM Manual Draft 7210). The threshold
level is that value for any particular watershed characteristic beyond which undesirable
consequences occur. In the case of a watershed in the Colorado River basin producing
significant salt yields, the threshold value chosen might well be a specific ton/acre/year salt
yield, e.g. 0,25. For The Greater Sagers Wash Watershed, the Team had to conduct the
watershed condition analysis before we had the salt yield data organized by geomorphic unit.
Therefore the decision as to satisfactory or not was much more a subjective call than it might
have been had salt yield been used as a numeric criterion,

Recognizing that the BLM salinity control efforts have been developed in response to a variety
of needs, and that the watershed condition analysis concept of H-1740-1 is not written
specifically for salinity situations, the Team preparing this comprehensive plan believed that our
work might benefit from, and be more complete in view of, some attempt at classifying The
Greater Sagers Wash Watershed as to watershed condition. The ranking results are shown in
Table 6.0.

l

The mountain side/mountain benches unit was classified SATISFACTORY, IDGH
VULNERABiliTY. TItis implies satisfactory condition, with high vulnerability to degradation
of the satisfactory condition. Under the prevailing land uses and management, deterioration of
condition to unacceptable watershed condition is quite possible, especially when stressed by
major stonn events. TItis unit has the least saline soils.

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