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At least 919 records · Page 51Linked to original sources
USGS2000

Monitoring The Water Quality of the Nation's Large Rivers Colorado River NASQAN Program

Since 1995, the National Stream Quality Accounting Network (NASQAN) of the U. S. Geological Survey (USGS) has focused on monitoring the water quality of the Nation's largest rivers including the Colorado, Columbia, Mississippi, and Rio Grande. The NASQAN program in the Colorado River Basin consists of eight stations that span seven basin States including Colorado, Wyoming, Utah, New Mexico, Arizona, Nevada, and California. Data collected from these stations are used to quantify the transport of chemical constituents and evaluate trends in water quality of the river. Currently, the NASQAN program in the Colorado River Basin is providing necessary data and information required by resource managers of the river who are responsible for meeting longstanding legal agreements that regulate the flow and quality of the river water.

Fact Sheet↗
USGS2016

Changes between early development (1930–60) and recent (2005–15) groundwater-level altitudes and dissolved-solids and nitrate concentrations In and near Gaines, Terry, and Yoakum Counties, Texas

Llano Estacado Underground Water Conservation District, Sandy Land Underground Water Conservation District, and South Plains Underground Water Conservation District manage groundwater resources in a part of west Texas near the Texas-New Mexico State line. Declining groundwater levels have raised concerns about the amount of available groundwater in the study area and the potential for water-quality changes resulting from dewatering and increased vertical groundwater movement between adjacent water-bearing units. In 2014, the U.S. Geological Survey, in cooperation with Llano Estacado Underground Water Conservation District, Sandy Land Underground Water District, and South Plains Underground Water Conservation District, began a multiphase project to develop a regional conceptual model of the hydrogeologic framework and geochemistry of the Ogallala, Edwards-Trinity, and Dockum aquifers. The Ogallala aquifer is the shallowest aquifer in the study area and is the primary source of water for agriculture and municipal supply in the area. This report describes the results of the first phase of the study, during which groundwater-level-altitude and selected water-quality data from wells in and near Gaines, Terry, and Yoakum Counties were compiled and evaluated for the Ogallala, Edwards-Trinity, and Dockum aquifers. Readily available digital groundwater data for the study area (geologic, well-construction, groundwater-level-altitude, and selected water-quality data) were compiled to assess temporal and spatial changes in groundwater resources from early development (1930–60) to recent (2005–15) periods. Pertinent data were compiled from available sources for the study area and for a 5-mile buffer area around the study area to prevent gridding errors near the boundary. Geologic and well-construction data were used to determine or verify the aquifer in which each well was completed. Depending on the available data, the aquifer assignment (aquifer in which a given well was completed) was determined on the basis of the following criteria, in order of priority: (1) the screened or open interval(s) of the well, (2) the total depth of the well, or (3) the completed aquifer reported for a given well by the data source. Potentiometric-surface maps were created to depict changes in groundwater-level altitudes for the Ogallala and Edwards-Trinity aquifers. In addition to comparing groundwater-level altitudes and water quality from the early development and recent periods, hydrographs of groundwater-level altitudes were created, and changes in water quality for various periods between 1930 and 2015 were evaluated. Variance maps for each groundwater-level-altitude grid were used to evaluate the spatial data coverage and to identify areas with higher uncertainty because of spatially limited data availability for some of the aquifers. For this report, existing dissolved-solids and nitrate concentration data were compiled and assessed for evidence of spatial patterns and changes over time. These data were compiled for samples collected from wells completed in the Ogallala, Edwards-Trinity, or Dockum aquifer during the early development period (1930–60) or the recent period (2005–15); temporal and spatial variations were assessed from depictions of the measured concentration values. Dissolved-solids and nitrate concentrations measured in samples from three wells completed in the Ogallala aquifer (well identifiers 11524, 11824, and 11825) for which long-term monitoring was done for various periods between 1950 and 2015 were also compiled and analyzed. Groundwater-level altitudes of the Ogallala aquifer are generally higher in the northwestern part of the study area and lower in the southeastern part of the study area, varying by as much as 800 feet. Groundwater flow paths for the early development period generally trend from northwest to southeast across the study area. Compared to those for the early development period, local features in the potentiometric surface for the recent period are more pronounced, likely as a result of additional data coverage, increased groundwater withdrawals, and local flow paths that are more variable. For the Edwards-Trinity aquifer potentiometric-surface map of the recent period, a general northwest to southeast flow gradient was also evident, with some subtle differences compared to the early development period. The Edwards-Trinity aquifer water-level-altitude change map between the early development and recent periods indicated similar spatial trends as in the Ogallala aquifer and indicated that groundwater-level altitudes declined over a large amount of the area for which sufficient data were available for reliably mapping changes. During the recent period, median dissolved-solids concentrations of less than 1,000 milligrams per liter (mg/L) were predominantly measured in the western part of the study area, and median concentrations of more than 1,000 mg/L were predominantly measured in the eastern part of the study area. A general pattern of increasing nitrate concentrations from west to the northeast was evident in the study area. Nitrate concentrations measured in samples collected from 16 wells completed in the Ogallala aquifer for the recent period were equal to or greater than 10 mg/L, the primary drinking water standard for finished drinking water.

Texas↗
USGS2019

Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2017

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is hydrologically defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift between San Acacia to the south and Cochiti Lake to the north. A 20-percent population increase in the basin from 1990 to 2000 and a 22-percent population increase from 2000 to 2010 resulted in an increased demand for water in areas within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when the Albuquerque Bernalillo County Water Utility Authority (ABCWUA) began treatment and distribution of surface water from the Rio Grande through the San Juan-Chama Drinking Water Project. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. The network currently (2017) consists of 122 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the ABCWUA and the New Mexico Office of the State Engineer, currently (2017) measures and reports water levels from the 122 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 122 sites through water years 2016 and 2017 (October 1, 2015, through September 30, 2017). Water levels that were collected from wells in previous water years were published in previous USGS reports.

New Mexico↗
USGS2019

Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2018

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is hydrologically defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift between San Acacia to the south and Cochiti Lake to the north. A 20-percent population increase in the basin from 1990 to 2000 and a 22-percent population increase from 2000 to 2010 resulted in an increased demand for water in areas within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when the Albuquerque Bernalillo County Water Utility Authority (ABCWUA) began treatment and distribution of surface water from the Rio Grande through the San Juan-Chama Drinking Water Project. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. As of 2018, the network consisted of 120 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the ABCWUA, the New Mexico Office of the State Engineer, and Bernalillo County, measures water levels from the 120 wells and piezometers in the network; this report, prepared in cooperation with the ABCWUA, presents water-level data collected by USGS personnel at those 120 sites through water year 2018 (October 1, 2017, through September 30, 2018). Water levels that were collected from wells in previous water years were published in previous USGS reports.

New Mexico↗
USGS2020

Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2019

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is hydrologically defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift between San Acacia to the south and Cochiti Lake to the north. A 20-percent population increase in the basin from 1990 to 2000 and a 22-percent population increase from 2000 to 2010 resulted in an increased demand for water in areas within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when the Albuquerque Bernalillo County Water Utility Authority (ABCWUA) began treatment and distribution of surface water from the Rio Grande through the San Juan-Chama Drinking Water Project. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. As of 2019, the network consisted of 120 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers screened at different depths.) The USGS, in cooperation with the ABCWUA, the New Mexico Office of the State Engineer, and Bernalillo County, measures water levels from the 120 wells and piezometers in the network; this report, prepared in cooperation with the ABCWUA, presents water-level data collected by USGS personnel at those 120 sites through water year 2019 (October 1, 2018, through September 30, 2019). Water levels that were collected from those discontinued wells in previous water years were published in previous USGS reports.

New Mexico↗
USGS2021

Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2020

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is hydrologically defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift between San Acacia to the south and Cochiti Lake to the north. A 20-percent population increase in the basin from 1990 to 2000 and a 22-percent population increase from 2000 to 2010 resulted in an increased demand for water in areas within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when the Albuquerque Bernalillo County Water Utility Authority (ABCWUA) began treatment and distribution of surface water from the Rio Grande through the San Juan-Chama Drinking Water Project. An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. As of 2020, the network consisted of 120 wells and piezometers. A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers screened at different depths. The USGS, in cooperation with the ABCWUA, the New Mexico Office of the State Engineer, and Bernalillo County, measures water levels from the wells and piezometers in the network; this report, prepared in cooperation with the ABCWUA, presents water-level data collected by USGS personnel at the sites through water year 2020 (October 1, 2019, through September 30, 2020). Water levels that were collected from discontinued wells in previous water years were published in previous USGS reports.

New Mexico↗
USGS2001

Known and suggested quaternary faulting in the midcontinent United States

The midcontinent United States between the Appalachian and Rocky Mountains contains 40 known faults or other potentially tectonic features for which published geologic information shows or suggests Quaternary tectonic faulting. We report results of a systematic evaluation of published and other publicly available geologic evidence of Quaternary faulting. These results benefit seismic-hazard assessments by (1) providing some constraints on the recurrence intervals and magnitudes of large, prehistoric earthquakes, and (2) identifying features that warrant additional study. For some features, suggested Quaternary tectonic faulting has been disproved, whereas, for others, the suggested faulting remains questionable. Of the 40 features, nine have clear geologic evidence of Quaternary tectonic faulting associated with prehistoric earthquakes, and another six features have evidence of nontectonic origins. An additional 12 faults, uplifts, or historical seismic zones lack reported paleoseismological evidence of large. Quaternary earthquakes. The remaining 13 features require further paleoseismological study to determine if they have had Quaternary earthquakes that were larger than any known from local historical records; seven of these 13 features are in or near urbanized areas where their study could affect urban hazard estimates. These seven are: (1) the belt of normal faults that rings the Gulf of Mexico from Florida to Texas. (2) the Northeast Ohio seismic zone, (3) the Valmont and (4) Goodpasture faults of Colorado. (5) the Champlain lowlands normal faults of New York State and Vermont, and (6) the Lexington and (7) Kentucky River fault systems of eastern Kentucky. Published by Elsevier Science B.V.

Engineering Geology↗
USGS1978

Gravity survey of the Tularosa Valley and adjacent areas, New Mexico

The gravity survey of the Tularosa Valley and adjacent areas is a compilation of gravity data acquired from several sources and reduced to the 1971 International Gravity Standardization Network datum. In addition, three local surveys were made that helped to fill in gaps in the gravity coverage. The resulting complete Bouguer gravity anomaly map and first- and third-order polynomial maps exhibit anomalies of great lateral extent and amplitudes that exceed 45 mGals. Five generalized geologic cross sections were constructed and analyzed by the two-dimensional method to investigate the thickness of the valley fill in Tularosa Valley and Jornada Del Muerto. On the basis of an assumed density contrast of 0.4 Mg/m3 between the valley fill. and the bedrock (pre-Cenozoic and Cenozoic rocks, undivided), the calculated depths to the pre-Cenozoic surfaces range from 1,372 to 2,743 m (4,500-9,000 ft).

Open-File Report↗
USGS1991

Jurassic Lake T'oo'dichi': A large alkaline, saline lake, Morrison Formation, eastern Colorado Plateau

A large alkaline, saline lake, Lake T'oo'dichi', occupied the entire eastern part of the Colorado Plateau region during deposition of the Brushy Basin Member of the Upper Jurassic Morrison Formation. The lake extended from near the site of Albuquerque, New Mexico, to near the site of Grand Junction, Colorado, and occupied a region that encompassed the San Juan and ancestral Paradox basins, making it the largest ancient alkaline, saline lake known.

Geological Society of America Bulletin↗
USGS2022

Geomorphic survey of North Fork Eagle Creek, New Mexico, 2019

The 2012 Little Bear Fire resulted in substantial loss of vegetation in the Eagle Creek Basin, south-central New Mexico, which has been expected to cause a variety of hydrologic responses that could influence geomorphic change to North Fork Eagle Creek. To monitor geomorphic change, surveys of a downstream study reach of North Fork Eagle Creek were conducted in 2017, 2018, and 2019 by the U.S. Geological Survey in cooperation with the Village of Ruidoso, N. Mex. The study included surveys of select cross sections, woody debris accumulations, and pools found in the channel of the study reach. During 2017–19, high-flow events resulting from both monsoonal rainfall and snowmelt runoff occurred in the study reach, and the events appeared to have caused some minor localized geomorphic changes in the study reach, which were evaluated through comparison of the 2017, 2018, and 2019 survey results. Comparisons of the cross-section survey results indicated that minor geomorphic changes had occurred in 4 of the 14 cross sections surveyed from 2017 to 2019. These geomorphic changes included aggradation or degradation of surface materials by about 1–2 feet in some parts of the affected cross sections. During the 2019 survey, 164 distinct accumulations of woody debris and 228 pools were identified in the study reach. Of the woody debris accumulations identified during the 2019 survey, 67 were certain to have also been present during the 2018 survey, and 21 were certain to have also been present during all three surveys (2017–19), indicating that most of the woody debris accumulations surveyed in 2017 were likely transported during the high-flow events between the 2017 and 2018 surveys. Most woody debris accumulations identified in 2019 did not appear to have substantially influenced geomorphic change in the locations where they were found but may have driven local geomorphic changes. Because the study began 5 years after the 2012 Little Bear Fire and the geomorphic scope of the study has so far been limited, it cannot be said that the changes observed between the 2017 and 2019 surveys are representative of a pattern of geomorphic change following the Little Bear Fire. Once geomorphic changes identified during the 2017 through 2019 surveys can be compared with results from the remaining planned geomorphic surveys, it may be possible to develop an understanding of the patterns in geomorphic change following the 2012 Little Bear Fire.

New Mexico↗
USGS1981

Estimating usable resources from historical industry data

Historical production statistics are used to predict the quantity of remaining usable resources. The commodities considered are mercury, copper and its byproducts gold and silver, and petroleum; the production and discovery data are for the United States. The results of the study indicate that the cumulative return per unit of effort, herein measured as grade of metal ores and discovery rate of recoverable petroleum, is proportional to a negative power of total effort expended, herein measured as total ore mined and total exploratory wells or footage drilled. This power relationship can be extended to some limiting point (a lower ore grade or a maximum number of exploratory wells or footage), and the apparent quantity of available remaining resource at that limit can be calculated. For mercury ore of grades at and above 0.1 percent, the remaining usable resource in the United States is calculated to be 54 million kg (1,567,000 flasks). For copper ore of grades at and above 0.2 percent, the remaining usable copper resource is calculated to be 270 million metric tons (298 million short tons); remaining resources of its by-products gold and silver are calculated to be 3,656 metric tons (118 million troy ounces) and 64,676 metric tons (2,079 million troy ounces), respectively. The undiscovered recoverable crude oil resource in the conterminous United States, at 3 billion feet of additional exploratory drilling, is calculated to be nearly 37.6 billion barrels; the undiscovered recoverable petroleum resource in the Permian basin of western Texas and southeastern New Mexico, at 300 million feet of additional exploratory drilling or 50,000 additional exploratory wells, is calculated to be about 6.2 billion BOE (barrels of oil equivalent).

Economic Geology↗
USGS1962

Exploration for uranium-vanadium deposits by U.S. Geological Survey 1948-56 in western Disappointment Valley area, Slick Rock district, San Miguel County, Colorado

The western Disappointment Valley area is in San Miguel County, Colo., in the northeastern part of the Slick Rock district, (see location map). It covers an area of approximately 50 square miles in Tps. 43 and 44 N., Rs. 17, 18, and 19 W., New Mexico principal meridian. The mining camp of Slick Rock is in the western part of the area. On the northeast the area is bounded by Gypsum Valley; the other boundaries are arbitrarily drawn to delimit the area in which drilling was done.

Colorado↗
USGS1937

Role of physical chemistry in stratigraphic problems

Stratigraphy is concerned mainly with the genesis and interpretation of stratified rocks, which include some of wide extent and of great scientific as well as economic interest that are largely of chemical rather than of detrital origin. Chemical agencies have been recognized to some extent in genetic studies of these rocks, but little work has been done approaching in maturity the type of study now given to the genesis of igneous rocks and of ores, in which physical chemistry plays so important a part.A plea is presented to geologists with training in physical chemistry to interest themselves in stratigraphic problems that involve the use of this science. Examples cited are the phosphate beds and bedded cherts of the Phosphoria formation in Idaho and adjacent States and the potash-bearing Salado halite of the Permian basin in New Mexico and Texas. The interplay of ions in the solutions from which these formations were derived must have been controlled by such conditions as temperature, pressure, degree of concentration, and the like. Possibly laboratory study would enable us to reproduce these conditions and results and thus better interpret the geologic history of the times when these formations were built.

Economic Geology↗
USGS2019

Hydraulic and water-quality indicators of aquifer zones contributing groundwater flow to wells in the Santa Fe Group aquifer system near southeast Albuquerque, New Mexico, 2013–16

An ethylene dibromide (EDB) plume extends approximately 5,880 feet northeast from the Bulk Fuels Facility on Kirtland Air Force Base. The leading edge of the EDB plume is about 3,700 feet upgradient from several water-supply wells. The water-supply wells are screened in the upper Santa Fe Group aquifer system. Within the upper Santa Fe Group, two primary clay-rich layers, the A1 and A2 units, separate water-producing zones. The U.S. Geological Survey, in cooperation with the Albuquerque Bernalillo County Water Utility Authority and the U.S. Air Force, installed four sentinel well nests and two aquifer-test pumping wells between the EDB plume and the water-supply wells. The purpose of the sentinel wells is to provide early warning of EDB plume migration towards water-supply wells. The sentinel well nests include at least three wells that are screened above, in between, and below the A1 and A2 units. The two aquifer-test pumping wells, installed for performing hydraulic tests on the aquifer system, are screened across both clay layers, as are the nearby water-supply wells. Well-bore flow logging indicated that greater than 60 percent of groundwater flow to the wells was through the deepest interval below the lowermost clay layer (A1 unit). The interval between the A1 and A2 units is the second most productive interval. Water-quality data also indicated that water drawn from the aquifer-test pumping wells and previously studied nearby water-supply wells is most similar in composition to water from the sentinel wells screened in the middle and deep intervals.

New Mexico↗
USGS2012

The effects of wildfire on the peak streamflow magnitude and frequency, Frijoles and Capulin Canyons, Bandelier National Monument, New Mexico

In June of 1977, the La Mesa fire burned 15,270 acres in and around Frijoles Canyon, Bandelier National Monument and the adjacent Santa Fe National Forest, New Mexico. The Dome fire occurred in April of 1996 in Bandelier National Monument, burned 16,516 acres in Capulin Canyon and the surrounding Dome Wilderness area. Both canyons are characterized by extensive archeological artifacts, which could be threatened by increased runoff and accelerated rates of erosion after a wildfire. The U.S. Geological Survey (USGS) in cooperation with the National Park Service monitored the fires' effects on streamflow in both canyons. Copyright 2004 ASCE.

Conference Paper↗
USGS1952

Memorandum on ground-water investigation of four proposed stock wells in Puertocito Area, Socorro County and Canoncito Area, Bernalillo and Valencia Counties, New Mexico

At the request of the Navajo Service, Office ot Indian Affairs, a groundwater iinvestigation of four proposed stock wells in the Puertocito Area, Socorro county and the Canoncito Area., Bernalillo and Valencia counties,New Mexico, was made in November, 1951 (see fig. 1). Although these areas are not on the Navajo Indian Reservation, they were included in the program of study of ground-water resources or the Navajo and Hopi Indian Reservations now being conducted by the Ground Water Branch of the United States Geological Survey. The work was financed by and was in cooperation with the Navajo Service, Office of Indian Affairs.

New Mexico↗
USGS2025

Tracking the sources of metals to the San Juan River, Four Corners Region, USA: An introduction to the thematic issue

Surface water quantity and quality is important for arid and semi-arid regions where many people, including underserved and Indigenous communities, rely on a scarce resource for drinking water, irrigation, livestock and ceremonial uses. The southwestern United States, and specifically the Four Corners Region (Colorado, Arizona, New Mexico and Utah), is an example of this situation. Elevated concentrations of metals including aluminium, arsenic and lead were identified in previous studies and this study in the San Juan River from below the Navajo Dam, through the Navajo Nation to Mexican Hat, Utah. An interdisciplinary team applied approaches and principles of geology, geochemistry, geomorphology, hydrology and statistics to gain a better understanding of the tributaries supplying the source(s) of metals to the San Juan River. This introductory paper provides an overview of the ‘Metal geochemical fingerprinting to identify sub-watershed source contributions to surface water at a regional arid watershed scale, Four Corners Region, USA’ thematic collection . An overview of sampling sites, techniques and potential sources of metals is provided. Approaches used in this study could be applied to investigations in similar systems globally.

Four Corners region↗
USGS2014

Potential postwildfire debris-flow hazards: a prewildfire evaluation for the Sandia and Manzano Mountains and surrounding areas, central New Mexico

Wildfire can drastically increase the probability of debris flows, a potentially hazardous and destructive form of mass wasting, in landscapes that have otherwise been stable throughout recent history. Although there is no way to know the exact location, extent, and severity of wildfire, or the subsequent rainfall intensity and duration before it happens, probabilities of fire and debris-flow occurrence for different locations can be estimated with geospatial analysis and modeling efforts. The purpose of this report is to provide information on which watersheds might constitute the most serious, potential, debris-flow hazards in the event of a large-scale wildfire and subsequent rainfall in the Sandia and Manzano Mountains. Potential probabilities and estimated volumes of postwildfire debris flows in the unburned Sandia and Manzano Mountains and surrounding areas were estimated using empirical debris-flow models developed by the U.S. Geological Survey in combination with fire behavior and burn probability models developed by the U.S. Department of Agriculture Forest Service. The locations of the greatest debris-flow hazards correlate with the areas of steepest slopes and simulated crown-fire behavior. The four subbasins with the highest computed debris-flow probabilities (greater than 98 percent) were all in the Manzano Mountains, two flowing east and two flowing west. Volumes in sixteen subbasins were greater than 50,000 square meters and most of these were in the central Manzanos and the western facing slopes of the Sandias. Five subbasins on the west-facing slopes of the Sandia Mountains, four of which have downstream reaches that lead into the outskirts of the City of Albuquerque, are among subbasins in the 98th percentile of integrated relative debris-flow hazard rankings. The bulk of the remaining subbasins in the 98th percentile of integrated relative debris-flow hazard rankings are located along the highest and steepest slopes of the Manzano Mountains. One of the subbasins is several miles upstream from the community of Tajique and another is several miles upstream from the community of Manzano, both on the eastern slopes of the Manzano Mountains. This prewildfire assessment approach is valuable to resource managers because the analysis of the debris-flow threat is made before a wildfire occurs, which facilitates prewildfire management, planning, and mitigation. In northern New Mexico, widespread watershed restoration efforts are being carried out to safeguard vital watersheds against the threat of catastrophic wildfire. This study was initiated to help select ideal locations for the restoration efforts that could have the best return on investment.

New Mexico↗