WSP09675

• File Number: 8041
• Description: 208 Clean Water Grant
• State: CO
• Date: 8/16/1982
• Author: CWCB
• Title: Quarterly Reports on the 208 Clean Water Grant for the Water Quality Control Division of the Coloradio Dept of Health
• Water Supply Pro - Doc Type: Publication

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nature of formations underlying soils above pagosa Springs and
the soluble nature of the Mancos Shale and Tertiary sediments
underlying soils below Pagosa. Mineral springs contributed an
additional 7,300 tons of salt during the study period.

Because of complex interrelations between diversions and
return flows within the Animas River, the Florida River, and the
Los pinos River drainages, a salt budget was prepared for the
entire area. An unspecified amount of irrigated acreage between
Durango and the state line for these three drainages contributed
12,000 tons of salt to the system during the study period.

The irrigation of 15,000 acres in Colorado along the La
Plata River added 20,000 tons of salt to the system. The
presence of Mancos Shale in the area accounted for the 1.4 tons
per acre per year rate of yield.

Relatively high total dissolved solids concentrations were
observed in the Mancos River drainage. The Mancos River above
Navajo Wash contributed a salt load of approximately 36,500 tons
during the study period. Irr igation return flow from the
Cortez-Towaoc area accounted for virtually all of the 29,000 tons
of salt added by Navajo Wash. Return flows from irrigation in
the Cortez area, supplied by water diverted from the Dolores
River, accounted for most of the flow in McElmo Creek. McElmo
Creek yielded 195,000 tons of salt during the study period.

Since the EPA has not determined total salt yieldS for all
of the San Juan tributaries in Colorado, it is not possible to
determine percentages of the total yield attributed to natural
and man caused sources as has been done for other Colorado River
Basin drainages in Colorado.

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