| Abstract: | This report contains a summary of data compiled from sources
throughout the Rio Grande Valley study unit of the National Water-
Quality Assessment program. Information presented includes the
sources and types of water-quality data available, the utility of
water-quality data for statistical analysis, and a description of
recent water-quality conditions and trends and their relation to
natural and human factors. Water-quality data are limited to
concentrations of selected nutrient species in surface water and
ground water, concentrations of suspended sediment and suspended
solids in surface water, and pesticides in surface water, ground
water, and biota.
The Rio Grande Valley study unit includes about 45,900 square
miles in Colorado, New Mexico, and Texas upstream from the
streamflow-monitoring station Rio Grande at El Paso, Texas. The
area also includes the San Luis Closed Basin and the surface-water
closed basins east of the Continental Divide and north of the
United States-Mexico international border. The Rio Grande drains
about 29,300 square miles in these States; the remainder of the
study unit area is in closed basins.
Concentrations of all nutrients found in surface-water
samples collected from the Rio Grande, with the exception of
phosphorus, generally remained nearly constant from the
northernmost station in the study unit to Rio Grande near Isleta,
where concentrations were larger by an order of magnitude. Total
nitrogen and total phosphorus loads increased downstream between
Lobatos, Colorado, and Albuquerque, New Mexico. Nutrient
concentrations remained elevated with slight variations until
downstream from Elephant Butte Reservoir, where nutrient
concentrations were lower. Nutrient concentrations then increased
downstream from the reservoir, as evidenced by elevated
concentrations at Rio Grande at El Paso, Texas.
Suspended-sediment concentrations were similar at stations
upstream from Otowi Bridge near San Ildefonso, New Mexico. The
concentration and estimated load were nearly two orders of
magnitude larger at this station relative to upstream stations.
Cochiti Lake allows suspended sediment to settle, thus the
resulting concentration is substantially lower downstream from
the reservoir. Downstream from Cochiti Lake, concentrations again
increased due to inflow from tributaries, other ephemeral streams
and arroyos, and agricultural and urban areas. Two ephemeral
tributaries (Rio Puerco and Rio Salado, which are south of
Albuquerque) contribute substantial amounts of suspended sediment
to the Rio Grande. Suspended-sediment concentrations in the Rio
Grande just downstream from Elephant Butte Dam decreased by
nearly three orders of magnitude due to settling in the reservoir.
Concentrations then increased due to agricultural and urban
impacts downstream from the reservoir.
Nutrients in ground water in the study unit do not appear to
be a widespread problem. However, localized areas that have
elevated nitrate concentrations have been documented. The largest
median nitrate concentration was found in water from wells
located in the Basin and Range-mountains-urban data stratum (3.0
milligrams per liter) and the smallest median nitrate
concentration was found in water from wells located in the
Southern Rocky Mountains-mountains-forest data stratum (0.08
milligram per liter). Few (3 percent) nitrate concentrations in
water from wells in all data strata were greater than 10
milligrams per liter, and most (82 percent) were less than 2
milligrams per liter. Comparison of nitrate concentrations in
water from wells located in specific land-use settings across all
hydrogeologic settings, with the exception of the Colorado
Plateau, indicated that the largest median nitrate concentration
was associated with rangeland land use and that larger nitrate
concentrations were found in water fr |
| Genre: | USGS Numbered Series |
| ProdID: | 25913 |
| Citation Author: | Anderholm, S. K.; Radell, M. J.; Richey, S. F. |
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| Citation Edition: | - |
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| Citation Language: | ENGLISH |
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| Citation Online Only Flag: | |
| Citation Phsyical Description: | xiv, 203 p. :ill., maps ;28 cm. |
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| Citation Public Comments: | |
| Citation Publisher: | U.S. Geological Survey, [Water Resources Division, New Mexico District] ;
USGS Earth Science Information Center, Open-File Reports Section [distributor], |
| Citation Series: | Water-Resources Investigations Report |
| Citation Series Code: | WRI |
| Citation Series Number: | 94-4061 |
| Citation Search Results Text: | Water-quality assessment of the Rio Grande Valley study unit, Colorado, New Mexico, and Texas; analysis of selected nutrient, suspended-sediment, and pesticide data; 1995; WRI; 94-4061; Anderholm, S. K.; Radell, M. J.; Richey, S. F. |
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| Citation Year: | 1995 |
| Type: | citation/reference |
| Text: | Water-quality assessment of the Rio Grande Valley study unit, Colorado, New Mexico, and Texas; analysis of selected nutrient, suspended-sediment, and pesticide data; 1995; WRI; 94-4061; Anderholm, S. K.; Radell, M. J.; Richey, S. F. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/wri/1994/4061/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/wri/1994/4061/report.pdf |
| Date Other: | Wed, 1 Nov 1995 00:00 -0600 |
| Publisher: | U.S. Geological Survey, [Water Resources Division, New Mexico District] ;
USGS Earth Science Information Center, Open-File Reports Section [distributor], |
