9521

• UCREFRP Catalog Number: 9521
• Author: Liebermann, T. D., D. K. Mueller, J. E. Kircher and A. F. Choquette.
• Title: Characteristics and Trends of Streamflow and Dissolved Solids in the Upper Colorado River Basin, Arizona, Colorado, New Mexico, Utah, and Wyoming.
• USFW Year: 1989.
• USFW - Doc Type: Denver.
• Copyright Material: NO

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EXPLANATION °D
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Carbonate plus bicarbonate a^,
Sulfate
¦ Chloride
Calcium
® Magnesium
Sodium plus potassium
(1948 - 50) Period of record
used for analysis 8
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58 61 62 63 64 67 68 69 70
Figure 21. Mean chemical composition of dissolved solids at selected sites in San Juan region. Cations on left, anions
on right.
per year (table 10). This trend represents a 12-percent change
in the median annual concentration during the 20-year period.
Animas River at Farmington, N. Mex. (site 62)
The Animas River is the largest tributary of the San
Juan River. At site 62 (table 3, pl. 1), near the mouth of
the river, mean annual runoff averages about 8.1 in. (table
9). Streamflow is somewhat regulated by Lemon Reservoir
and Electra Lake, and about 30,000 acres is irrigated up-
stream from the site. The streamflow hydrograph shows a
typical snowmelt-runoff peak in June and steady base flow
during the winter months (fig. 22C). Mean annual flow-
weighted dissolved-solids concentration is greater than at site
61, averaging about 263 mg/L. Calcium and bicarbonate are
the predominant ions during the high-flow season. Calcium
and sulfate predominate during the low-flow season.
No statistically significant annual monotonic trends in
streamflow or dissolved solids were detected during 1955-83.
However, monthly concentrations of dissolved sodium and
chloride decreased significantly, mainly during the low-flow
season.
San Juan River at Farmington, N. Mex. (site 63)
Site 63 (table 3, pl. 1) is just downstream from the
mouth of the Animas River. Irrigated area upstream from
the site totals about 86,000 acres. Streamflow is controlled
partly by Navajo Reservoir, and the period of record
(1962-82) is essentially the same as the postintervention
period for site 61. Streamflow is a combination of the
regulated streamflow of the San Juan River and the seasonal
streamflow of the Animas River. Streamflow peaks during
June, and it is maintained at about 1,200 ft3/s during the
San Juan Subregion 51