U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 032-99

September 1999

New Mexico

Middle Rio Grande Basin Study

The Middle Rio Grande Basin, the

area within the Rio Grande Valley

extending from Cochiti Dam downstream to San Acacia, is the focus of a

5-year study by the U.S. Geological

Survey (USGS) and other agencies to

improve understanding of the area’s

water resources. The Santa Fe Group

aquifer is the main source of municipal water. The New Mexico Office of

the State Engineer manages the water

resources in the basin and has declared the basin a “critical basin”—a

ground-water basin faced with rapid

economic and population growth for

which technical information about the

available water supply is inadequate.

The study began in 1995, and it is

scheduled to be completed in 2000.

Additional information can be found

at http://rockyweb.cr.usgs.gov/mrgb/.

Ground-Water Studies

Projects are underway to improve

understanding of how water enters

and moves through the aquifer.

Recharge where streams and arroyos

enter the basin is being estimated by

methods such as changes of groundwater temperature with aquifer depth,

chemical tracer studies, laboratory

examination of core samples, and

streamflow measurements at multiple

reaches. Environmental tracers are

being used to trace and date water

moving through the aquifer (fig. 1).

Ground-water temperature profiles of

water in wells installed near the Rio

Grande are being used to determine

the volume of water passing between

the river and the aquifer. Electromagnetic surveys of the inner valley of

the Rio Grande were done to help

map the extent of clay layers beneath

the riverbed that retard recharge to

the aquifer from the river.

Hydrogeologic Framework

The USGS, in cooperation with the

New Mexico Bureau of Mines and

Mineral Resources (NMBMMR) and

faculty and students at the University

of New Mexico and the New Mexico

Institute of Mining and Technology,

is studying the basin’s hydrogeologic

framework. Geologic mapping of

more than 35 1:24,000-scale quadrangles is being done in cooperation

with the NMBMMR. Stratigraphic

studies of Santa Fe Group sedimentary units (fig. 2) include description

of depositional environments and age

and grain-size analysis. Depositional

environments and grain size influence

the permeability of rocks that make

up the aquifer. Faults are studied in

detail to determine the amount and

timing of horizontal displacement and

their effect on depositional patterns in

the Santa Fe Group.

Geophysical techniques are providing

important information about the

structure of the basin and the sedimentary units that compose the

aquifer. Among those techniques are

airborne high-resolution magnetic

(fig. 3) and electromagnetic surveys

and ground-based gravity and electromagnetic surveys. These surveys

have successfully identified faults

that offset the Santa Fe Group and

rock properties that control potential

aquifer yield.

Urbanization

In 1990, 89 percent (502,100) of the

basin’s residents lived in the Albuquerque urban area. During the past

century, the city’s population increase

has accounted for about 30 percent of

New Mexico’s growth (fig. 4). The

USGS is mapping historical land use

and land cover to model the basin’s

future urban growth.

Figure 1. Collecting water samples for

environmental tracers from the Rio

Grande north of Albuquerque.

Figure 2. Exposed sedimentary units

of the Santa Fe Group.
science for a changing world

The Middle Rio Grande Council of

Governments is developing a regional

land-use plan (FOCUS 2050) and,

with the technical assistance of the

USGS, a land-use analysis model that

will produce a long-range strategy for

managing urban growth. The ultimate

goal of this urban-growth modeling is

to provide the basis for a comprehensive, quantitative analysis of alternative land-use patterns.

Rio Puerco Assessment

The Rio Puerco Basin, which covers

6,177 square miles of northwestern

New Mexico (fig. 5), supplies more

than 70 percent of the sediment

carried by the Rio Grande upstream

from Elephant Butte Reservoir. The

USGS, in conjunction with the Rio

Puerco Watershed Management

Committee, Bureau of Land Management, Bureau of Reclamation,

Colorado State University, and the

Universities of New Mexico and

Vermont, is assessing the sources,

transport, and deposition of sediment

in the Rio Puerco. The objective of

the project is to determine the roles of

bedrock, soils, vegetation, climate,

and land use in sediment deposition/

erosion cycles.

Late 19th century arroyo carving and

subsequent sediment deposition are

being documented through repeat

photography, streamflow and sediment gaging, sediment trap studies,

and geochemical and isotopic investigations. The past 30,000 years of

arroyo physiography is being studied

with mapping and radiocarbon

analysis of fluvial sediments.

The future response of the basin to

climate cycles and land-use changes

is being studied using remote sensing,

“ground-truth” monitoring, and

computer modeling to provide

information for minimizing unwanted

consequences of land-use decisions.

More information can be found at

http://climchange.cr.usgs.gov/rio_

puerco/.

Hydrologic Monitoring

Hydrologic data are essential for

monitoring and managing New

Mexico’s limited water resources.

The USGS network of water datacollection stations throughout New

Mexico records information on

streamflow and streamwater levels,

reservoir and lake storage, groundwater levels, spring discharge, and

water quality. These stations are

funded in cooperation with Federal,

State, tribal, and local agencies. The

data-collection program in New

Mexico consists of 196 continuous

streamflow-gaging stations, 32

streamflow partial-record stations, 43

water-quality stations, 46 precipitation stations, and 7,265 wells.

Source, Transport, and Fate of

Mercury in South-Central New

Mexico

As early as 1971, mercury concentrations in fish from some New Mexico

reservoirs exceeded human-health

guidelines. USGS scientists from the

New Mexico Cooperative Fish and

Wildlife Research Unit are working

to determine the source of the mercury contamination.

Figure 3. Airborne high-resolution magnetic data for the central Middle Rio

Grande Basin and features related to faults and volcanic rocks, terraces and

gullies, and manmade metallic items.

Mz

Qb

QTs

QTs

QTs

mapped, basin-bounding fault

Rio

Grande

25

Rio

Rancho

Albuquerque

pipeline

Intra-basinal

faults

Intra-basinal

faults

arroyo

arroyos

power poles

land fill

land fill

commercial

 buildings

water

tank

 river 

terraces

or faults

arroyo

Intra-basinal

faults

industrial

complex

HIGH-RESOLUTION AEROMAGNETIC MAP - RIO RANCHO SURVEY 

Scale

106° 52'30" 106° 45' 106° 37'30"

35° 22'30" 35° 15'

0

-500

-750

nanoteslas, illuminated from the east 250

Magnetic flux density

0 5 Kilometers

0 5 Miles

Explanation of Geologic Symbols

Qb - Quaternary basalt

QTs - Quaternary/Tertiary Santa Fe 

 Group (basin-fill sediments)

Mz - Mesozoic sedimentary rocks

Figure 4. Growth of the Albuquerque

urban area.

1935 Urban Area 1951 Urban Area

1973 Urban Area 1991 Urban Area

Urban Area Roads Railroads

0 5 10 Miles

0 5 10 Kilometers

Scale
New Mexico

Airborne mercury is captured by rain

drops and deposited on the landscape

when it rains. Gaseous and particlebound mercury deposition from the

air during dry periods might also

contribute to mercury contamination.

Once in the aquatic food chain,

concentrations of mercury may

increase 300 fold passing from

microscopic plants and animals to

fish. Thus, even small amounts of

atmospheric deposition of mercury

may significantly increase mercury

concentrations in fish, with possible

implications for ecological and

human health.

Wildfires also may contribute to

mercury loading and availability in

reservoirs. Following a fire at the

headwaters of Caballo Reservoir,

mercury concentrations in reservoir

sediments collected near the burned

site were greater than those at other

reservoir sites. Concentrations of

methylmercury, one of the most toxic

forms of mercury, were as much as

six times higher; this increase may

have been related to increased

sediment-inhabiting bacteria populations enhanced by carbon-rich, burnt

vegetation carried to the reservoir by

runoff from summer rains. The

results of this study could be used to

integrate fire-management and

reservoir-management planning.

Water Resources on Pueblo Lands

The USGS has cooperative projects

with the Pueblo of Jemez and the

Pueblo of San Ildefonso to describe

water resources on pueblo lands. The

primary objective of the Pueblo of

Jemez project is to continue the

water-quality sampling program to

determine the extent of environmental effects from internal and external

sources on the hydrologic system of

the upper Jemez River watershed.

The Pueblo of San Ildefonso project

focuses on a water-quality assessment of pueblo lands. This assessment includes collecting, analyzing,

and interpreting surface-water,

bottom-sediment, and ground-waterquality data for pueblo lands and

adjacent U.S. Department of Energy

lands.

Coalbed Methane in the San Juan

Basin

In the 1970’s, coalbed methane was

discovered in commercial quantities

in Fruitland Formation coalbeds in

the San Juan Basin in northwestern

New Mexico. Coalbed gas production

reached an annual production rate of

940 billion cubic feet in 1997.

Approximately 3,000 wells now

produce coalbed methane in the

basin.

The USGS has been conducting a

detailed study of coal resources of the

Fruitland Formation as part of its

National Coal Assessment Program.

Preliminary results show that the

Fruitland contains about 230 billion

tons of coal in the basin. Because the

San Juan Basin is the world’s largest

producer of coalbed methane, current

studies of the occurrence and yield of

this resource in the basin may provide

models for predicting coalbed methane distribution in other basins.

Fire Ecology

Fire is a key process in most southwestern ecosystems, yet current

knowledge of the ecological effects of

past and present fires is inadequate to

support informed resource management. USGS scientists are studying

fire scars on trees (fig. 6), charcoal

deposits in ancient bog sediments,

and historical photographs of landscape changes in Bandelier National

Monument and the Santa Fe National

Forest to reconstruct regional fire

histories of the Jemez and Sangre de

Cristo Mountains. Historical patterns

help define the natural variability

among fires including their frequency,

extent, seasonality, and severity. This

information is needed to define the

role of fires and to assess and manage

forest health and restoration needs.

The effects of modern fires on forest

communities and processes also are

being examined; these study topics

range from Mexican spotted owls and

salamanders to arthropods and the

nitrogen cycle. Collaborators include

the University of Arizona Tree-Ring

Figure 6. Studying fire scars on trees.

Figure 5. Rio Puerco Basin.

AB: Albuquerque

AC: Arroyo Chavez

B: Bernardo

C: Cabezon Peak

CA: Arroyo Chico

LV: La Ventana

MP: Mesa Prieta

MT: Mount Taylor

RG: Rio Grande

RP: Rio Puerco

SL: San Luis

SR: Sierra Nacimiento

New Mexico

AC

CA

MT

B

RP

RG

AB

MP

C

SL

LV

SR
Printed on recycled paper

USGS office locations USGS State Representative

5338 Montgomery Blvd. NE

Suite 400

Albuquerque NM 87109-1311

(505) 830-7900

FAX (505) 830-7998

USGS Home Page

http://www.usgs.gov

Reports and products

1-888-ASK-USGS

A multibureau Shared-Water Resources Issues Team was created in

the U.S. Department of the Interior to

identify, compile, and communicate

shared-water resources issues in the

U.S.-Mexico border area. Additional

information can be found at http://

www.doi.gov/fcc/.

Geospatial Data Status

The USGS is developing DOQ

coverage of New Mexico. More than

2,600 DOQ’s will be generated using

black-and-white and color infrared

aerial photography acquired by the

National Aerial Photography ProThe USGS has 115

employees in New Mexico

Las Cruces

Albuquerque

Carlsbad

Los Alamos

gram. Approximately 75 percent of

New Mexico is covered by either

completed or “authorized for production” DOQ’s.

The Digital Elevation Model (DEM)

Program for New Mexico is complete for the 1:100,000-scale map

series. The state 1:24,000-scale map

coverage is complete with either 10-

meter- or 30-meter-resolution

DEM’s. DEM’s are sampled rectangular areas of regularly spaced

elevations used to show topographic

relief. They will be used for hydrologic modeling, flood analysis,

streamflow dynamics, and hazard

mitigation.

Laboratory, Northern Arizona University, University of New Mexico,

Los Alamos National Laboratory, and

Santa Fe National Forest.

United States-Mexico Border

Mapping and Shared-Water

Resources

New Mexico is one of four States

involved in U.S.-Mexico border

mapping and shared-water resources

activities (fig. 7). The USGS is

working with Federal, State, and

local agencies and other organizations in the United States and Mexico

to develop digital map data for a 100-

mile zone on each side of the border.

From color infrared aerial photography for the U.S. side of the border,

the USGS is producing digital

orthophoto quadrangles (DOQ’s).

DOQ’s are scanned, high-resolution

aerial photographs in which distortion

and displacements caused by the

camera orientation and terrain have

been removed. A DOQ may be

incorporated into a computerized

geographic information system and

used with other data layers for

analysis and geographic applications.

The USGS has digitized boundary

and Public Land Survey System

Digital Line Graphs (DLG’s) from

USGS 1:24,000-scale maps of the

U.S. border area. Transportation and

hydrologic feature DLG’s are scheduled for production under the U.S.

Department of the Interior High

Priority Base Data Program. The

USGS also has produced 1:24,000-

scale Digital Raster Graphics

(DRG’s) of 1:24,000-scale maps in

the border area. DRG’s are scanned

images of USGS topographic maps

that depict features such as lakes and

streams, highways and railroads,

boundaries, geographic names,

elevation, and topography.

Yuma

San Die San Diegogogogo

Laredo

No El Paso Nogales gales g

Del Rio

TEXAS

CALIFORNIA

ARIZONA NEW MEXICO

SONORA CHIHUAHUA

COAHUILA

100% Complete

Digital Elevation Model

Aerial Photography

Digital Raster Graphic

NUEVO

LEON TAMAULIPAS

Digital Orthophoto Quadrangle

30% Complete - 70% In progress

Digital Line Graph

PLSS 100% Complete

Boundary 100% Complete

Hydrography 18% Complete

Transportation 18% Complete

Hypsography 18% Complete

U.S. M a p p i n g S t a t u s

BAJA

CALIFORNIA

TAMAULIPAS

No ales

Figure 7. United States-Mexico transboundary mapping.