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Research about Colorado

Source-linked reports with geographic coverage including Colorado.

At least 1,603 records · Page 89Linked to original sources
USGS1978

Reconnaissance map showing relative amounts of soil and bedrock in the mountainous part of the Pinewood Lake-Carter Lake Reservoir quadrangles, Boulder and Larimer counties, Colorado

This map shows the relative amounts of soil and hard bedrock within the upper 6 feet (1.8 m) of the land surface. (See schematic section.) It provides information useful for broad-scale land-use decisions. The map is based on reconnaissance field studies and aerial-photograph interpretation. The depth of soil and weathered rock was measured directly in roadcuts and other excavations and was estimated from seismic profiles in areas of few or no excavations or outcrops. Secondary characteristics of map units, such as percentage of outcrop in a given area, steepness of slope, type and amount of vegetation cover, and general appearance of the landscape, were used in drawing the boundaries between map units. Localities were assigned to the different map units by field inspection; lines separating the different map units were then drawn by aerial-photograph interpretation and were transferred photogrammetrically to the base map.

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USGS1978

Effects of grazing on runoff and sediment yield from desert rangeland at Badger Wash in western Colorado, 1953-73

Four different systems of livestock management were compared hydrologically during a 20-year study (November 1953-November 1973) in western Colorado. These systems were grazing by cattle and sheep from November 15 to May 15 each year, complete elimination of grazing, grazing by sheep from November 15 to February 15 each year, and grazing by sheep from November 15 to February 15 every other year. Grazing by both cattle and sheep from November 15 to May 15 each year was the standard grazing practice in the area at the beginning of the study. Complete grazing exclusion resulted in a reduction in runoff of about 25 percent during the period 1953-65 and an additional 25 percent during 1966-73. During the same periods sediment yield was reduced by 35 and 28 percent, respectively, for a total of 63 percent. A change in grazing use from cattle and sheep, November 15-May 15 each year, to sheep only at approximately the same utilization rate, November 15-February 15 each year, was accompanied by a reduction in runoff and sediment yield of about 29 percent. The same change in use, except that grazing was allowed every other year during the sheep grazing period, resulted in a reduction in runoff and sediment yield of about 20 percent. Recurrence intervals of annual runoff occurring on three soil types at Badger Wash are provided. These data may be applied to similar soils in areas of like climate and physiography shown on accompanying maps.

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USGS1978

Hydrologic reconnaissance of the Yampa River during low flow, Dinosaur National Monument, northwestern Colorado

A hydrologic reconnaissance of a 74-kilometer reach of the Yampa River in Dinosaur National Monument was made during low flow in mid-August 1976. Stream discharge, which was measured along this reach every 16 to 24 kilometers, ranged from 9.4 to 10.6 cubic meters per second. Variations in streamflow were explained, in part, by underflow, loss to ground water, and evaporation. Specific conductance was measured about every 2 kilometers and indicated a downstream increase on the order of 11 to 12 percent for the reach. Except for mercury, bottom-sediment trace-element concentrations in the study reach were less than maximum concentrations determined during August-September 1976 for bottom sediments at unperturbed sites upstream in the Yampa River basin. At one of five sampling sites, the mercury concentration in bottom sediments exceeded the maximum measured upstream level.

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USGS1978

Anomalous occurrence of uranium in alpine peats, Summit County, Colorado, and results of a simple sample fractionation procedure

Samples from Summit County, Colo., were fractionated for analyses of organic content and uranium. The uranium is related to organic content but not to type of organic matter. In one area uranium values are around 100 ppm in bulk samples and as much as 200 ppm in certain separated fractions of the samples; this is much higher than the 1-10 ppm normal uranium values for peat.

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USGS1978

Evaluation of hydrogeologic aspects of proposed salinity control in Paradox Valley, Colorado

The salt load in the Dolores River increases by about 200,000 tons per year where it crosses Paradox Valley, Colorado, because of the discharge of a sodium chloride brine from an underlying aquifer. A ground-water management program to nearly eliminate this major source of salt, which eventually enters the Colorado River, can be designed on the basis of an accurate description of the hydrogeologic framework of Paradox Valley.

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USGS1978

Effects of converting sagebrush cover to grass on the hydrology of small watersheds at Boco Mountain, Colorado

Changes in runoff and sediment yield caused by changing sagebrush cover to grass cover were studied at four small watersheds in western Colorado during a 9-year period. Measurements of runoff and sediment yield from four watersheds were made for 3 years, at which time two watersheds were plowed and seeded to beardless bluebunch wheatgrass. The same measurements were then continued for an additional 6 years. Measurements indicated that conversion to grass caused a reduction in runoff from summer rainstorms of about 75 percent. Runoff from spring snowmelt increased about 12 percent and annual runoff from treated watersheds decreased about 20 percent when compared to control watersheds. Sediment yield from the seeded watersheds was reduced by about 80 percent. Most of this reduction is related to the decrease in runoff from summer rainstorms. The size of barren interspaces between plants was reduced on the converted watersheds to about 30 percent of those on the untreated watersheds. Linear regression analysis indicates that a reduction of 38 percent in the amount of bare soil resulting from planting grass would result in a decrease of 73 percent in sediment concentration.

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USGS1978

Hydrologic data for urban storm runoff from three localities in the Denver metropolitan area, Colorado

Urban storm-runoff data, collected from 1975 to 1977, on three catchment areas in the Denver, Colo., metropolitan area are presented. The catchment are predominantly a single-family residential catchment area in Littleton, a multifamily residential and commercial catchment area in Lakewood, and a high-density residential and commercial catchment area in Denver. Precipitation, rainfall-runoff, snowmelt-runoff, water-quality (common constituents, nutrients, biochemical oxygen demand, coliform bacteria, and solids, trace elements, and pesticides), and catchment-area data are necessary to use the U.S. Environmental Protection Agency 's Storm Water Management Model II. The urban storm-runoff data may be used by planning, water-management, and environmental-protection agencies to assess the impact of urban storm runoff on the hydrologic system. (Woodard-USGS)

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USGS1978

Water-level records for the northern High Plains of Colorado, 1974-78

Water-level measurements were made in more than 600 wells in January 1978 in the northern High Plains of Colorado. Changes in water levels from January 1977 to January 1978 ranged from a rise of about 22 feet in Phillips County to a decline of about 14 feet in Yuma County. Measurements for January 1978 and the four preceding winters are given in a table.

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USGS1978

Hydrologic and geomorphic data from the Piceance Basin, Colorado, 1972-77

This report is a compilation of erosion measurements made at 121 channel sites and 45 hillslope sites during the period 1972-77 in the Piceance basin of northwestern Colorado. The data were collected as part of channel-morphology, sediment-transport, and erosion-rate studies being conducted in conjunction with development of the oil-shale resource of the area. The channel measurements were made to determine rates of aggradation, degradation, and lateral movement. Hillslope measurements were obtained to determine rates of soil erosion in the area. No analyses, results, or conclusions are included in this report.

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USGS1978

Coal resources of the Fish Creek EMRIA site, Routt County, Colorado

The Fish Creek EMRIA site, an area of about 3.7 square miles (9.6 km2), is located in the southeastern part of the Yampa coal field on the steep to gently dipping beds of the Upper Cretaceous Williams Fork Formation. The Fish Creek coal bed within 200 feet (60 m) of the surface was evaluated by five core holes. Coal resources--measured, indicated, and inferred--within the site are 2,512,000 short tons, 7,970,000 short tons, and 507,000 short tons respectively. The coal has an apparent rank of bituminous C. The average Btu value of three core samples from the site on the as-received basis is 10,790, average ash content is 11.1 percent, and average sulfur content is 1.9 percent. A comparison of the analyses of samples from the Fish Creek coal bed with other Rocky Mountain province coal sample analyses shows that nitrogen, total sulfur, and pyritic and organic sulfur contents are noticeably higher in the Fish Creek coal bed samples. A comparison of other element analyses shows that the Fish Creek coal bed is noticeably higher in As, Cr, F, Fe, Hg, and Sr, and noticeably lower in Th.

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USGS1978

Reconnaissance evaluation of water resources for hydraulic coal mining, Crested Butte coal field, Gunnison County, Colorado

Available surface-water and ground-water data were compiled for the parts of the Gunnison River basin in and adjacent to the Crested Butte coal field. The data were evaluated to assess the quantity and quality of water resources in the area for use in hydraulic coal mining. Based on discharge records, surface-water supplies of most streams should be adequate to meet the demands for hydraulic mining of 1 million tons of coal per year with a recycled water system. However, on some of the smaller streams in the area, some storage of water may be required for use during low-flow periods to meet minimum-flow requirements for downstream reaches. Ground water from alluvium along major streams and rivers and, in certain parts of the study area, from the Dakota and Entrada Sandstones, is also a potential source of water for hydraulic coal mining. The surface and ground water in the study area should be of adequate quality for use in hydraulic coal mining, with the possible exception of Coal Creek which has excessive concentrations of iron, manganese, and zinc. Data are insufficient to assess the potential impact of hydraulic coal mining on downstream water quality.

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USGS1978

Intrusive rocks northeast of Steamboat Springs, Park Range, Colorado

Major Precambrian and minor Tertiary intrusive rocks northeast of Steamboat Springs in the Park Range between 40°30' and 40°45' N. lat. are described and compared with related rocks elsewhere in Colorado and Wyoming. The Precambrian intrusives were emplaced in a sequence of high-grade interlayered felsic gneisses, amphibolites, and pelitic schists of sedimentary and volcanic origin. These rocks are cut by a major northeast-trending Precambrian shear zone where mainly left lateral movement of 1/ 2 to 1 mile is certain. Cumulative movement of many miles is possible. The Precambrian intrusives consist of a batholith, the Mount Ethel pluton, a smaller Buffalo Pass pluton, and small dikes or lenses of fine-grained porphyry, pegmatites, and ultramafics. The Mount Ethel pluton is an oval shaped body 7 miles wide by about 40 miles long (shown by geophysical data to extend beneath younger sediments in North Park). Outer batholithic contacts are sharp and dip steeply outward at about 85°. Five mappable internal variants consist, in order of decreasing age, of granodiorite, quartz monzonite porphyry of Rocky Peak, quartz monzonite of Roxy Ann Lake, granite and quartz monzonite, and. leucogranite. Internal contacts between these plutonic variants are sharp, and evidence of liquid-solid relationships abounds; despite this, all rocks except the granodiorite contribute to an Rb-Sr whole-rock isochron indicating emplacement about 1.4 b.y. (billion years) ago. The most important variants volumetrically are: the quartz monzonite porphyry of Rocky Peak, which forms an irregular 2-mile-thick carapace or mapped band around the west edge of the pluton and is lithologically similar to nearby Sherman Granite, and the quartz monzonite of Roxy Ann Lake, which forms most of the rest of the pluton and is lithologically similar to Silver Plume Granite. An apparent Sherman -Silver Plume dichotomy with similar rock types and similar relative ages is noted throughout Colorado plutons of that age. The Buffalo Pass pluton consists of the quartz monzonite and gra- nodiorite augen gneiss of Buffalo Mountain and equigranular quartz monzonite gneiss. Internal contacts are not exposed. These rocks contribute to an Rb-Sr whole-rock isochron indicating syntectonic emplacement 1.7-1.8 b.y. ago, essentially the same as the metamorphism of the felsic gneiss wallrocks in the area of this report, and of rocks of Boulder Creek age elsewhere in Colorado. The fine-grained porphyry dikes cut the Buffalo Pass pluton, the ultramafics, and some pegmatites. The dikes are within the age range of the Mount Ethel pluton and are older than the mylonite and shear zones. They occur in both an older northwest-trending and a somewhat younger northeast-trending set but do not appear to change compositionally from one set to the other. Regional considerations indicate that they were emplaced between about 1.1 and 1.5 b.y. ago, a time when intermediate to mafic dikes were commonly emplaced throughout Colorado, Wyoming, and southwestern Montana. The pegmatite and ultramafic bodies are not dated directly, but clustering of many pegmatites outside the contacts of the Mount Ethel pluton may indicate a genetic relation of the pegmatites to the Mount Ethel rocks. Fluorite is a common accessory mineral in the rocks of the Mount Ethel pluton; it has not been observed in this area in the petrographically similar rocks of the Buffalo Pass pluton. Fluorite was precipitated most abundantly from the Precambrian magma that formed the quartz monzonite of Roxy Ann Lake. In 70 percent of these rocks fluorite is observed in amounts as great as 2 percent and is successively less abundant in both older and younger plutonic phases. Textural evidence indicates that, although most fluorite is intergrown with and contemporaneous with other magmatic minerals, some fluorite is associated with alteration minerals in a manner demonstrating its mobility since its initial deposition.

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USGS1978

Water resources data for Colorado, water year 1977: Volume 3. Dolores River basin, Green River basin, San Juan River basin

Water-resources data for Colorado for the 1977 water year consists of records of stage, discharge, and water quality of streams; stage, contents, and water quality of lakes and reservoirs, and water levels and water quality of wells and springs. This report (Volumes 1, 2, and 3) contains discharge records for 424 gaging stations, stage and contents of 25 lakes and reservoirs, 5 partial-record flow stations, 79 crest-stage partial-record stations, and 193 miscellaneous sites; water quality for 134 gaging stations and 60 miscellaneous sites; and water levels for 55 observation wells. A few pertinent stations in bordering States are also included in this report. The records were collected and computed by the Water Resources Division of the U.S. Geological Survey under the direction of J. F. Blakey, district chief. These data represent. that portion of the National Water Data System collected by the U.S. Geological Survey and cooperating State and Federal agencies in Colorado.

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