Geology topics

Research about Pueblo County, Colorado

Source-linked reports with geographic coverage including Pueblo County, Colorado.

4 recordsLinked to original sources

USGS2002

Evaluation of possible alternatives to lower the high water table of St. Charles Mesa, Pueblo County, Colorado

St. Charles Mesa, an upland terrace southeast of Pueblo, Colorado, has become increasingly urbanized as cultivated fields have been subdivided and converted to residential areas. In some areas, the water table in the terrace alluvial aquifer underlying St. Charles Mesa is very shallow. Bessemer Ditch, which delivers irrigation water to farms on the mesa and other areas of the lower Arkansas River Valley, traverses St. Charles Mesa along its southern side and is the principal source of recharge to the terrace alluvial aquifer. The ground-water flow system was assumed to be in a state of dynamic equilibrium (steady-state condition) for this study. A steady-state ground-water flow model of the terrace alluvial aquifer was constructed and calibrated. The model was run in transient state to evaluate possible alternatives of lowering the water table. The possible alternatives evaluated were (1) reducing areal recharge by reducing recharge to irrigated areas by 25 percent, (2) lining Bessemer Ditch from (a) Aspen Street to 21st Lane; (b) Aspen Street to 23rd Lane; (c) Aspen Street to 25th Lane; and (d) Aspen Street to Nicholson Road, (3) installing two drains at a depth of 10 feet below land surface upgradient from the high water table areas, and (4) installing 22 dewatering wells within the high water table areas, each pumping at 80 gallons per minute. All alternatives evaluated were at least partly effective in lowering the water table. As the simulated extent of Bessemer Ditch lining was increased, the extent and magnitude of simulated water-table declines also increased. The maximum simulated declines in the water table were 3 feet when simulated areal recharge to irrigated areas was reduced by 25 percent, 29 feet when lining of Bessemer Ditch was simulated from Aspen Street to Nicholson Road, 6.8 feet when two drains were simulated at 10-foot depth, and 14.4 feet when 22 dewatering wells, each pumping at 80 gallons per minute, were simulated. Lining Bessemer Ditch from Aspen Street to 25th Lane and from Aspen Street to Nicholson Road both resulted in water-table declines of at least 5 feet throughout most of the area. Except for reducing recharge to irrigated areas and installation of the two drains, all the alternatives evaluated probably would lower the water table enough to diminish the ground-water supply available for at least some existing wells.

Colorado↗

USGS1989

Hydrogeologic characteristics of the Valley-Fill aquifer in the Arkansas River valley, Pueblo County, Colorado

The hydrogeology of the valley-fill aquifer of the Arkansas River valley in Pueblo County, Colorado is presented in a series of three maps. The map shows: (1) the altitude and configuration of the bedrock surface beneath the valley-fill material; (2) the altitude and configuration of the water table in the spring of 1966; and (3) the saturation thickness of the valley-fill aquifer in the spring of 1966.

Colorado↗

USGS1980

Calibration and potential uses of a digital water-quality model for the Arkansas River in Pueblo County, Colorado

The U.S. Geological Survey conducted a 1-year study to calibrate and demonstrate the use of a steady-state water quality model for a 42-mile reach of the Arkansas River in Pueblo County, Colo. Based on the calibration, the model is capable of accurately predicting concentrations of carbonaceous biochemical oxygen demand, total organic nitrogen, total nitrite, and total orthophosphate; predicted concentrations of total ammonia, total nitrate, and dissolved oxygen will be somewhat less accurate. Additional data are needed to determine the model's capability to predict concentrations of coliform bacteria. Potential uses of the model were demonstrated by simulating the effects of different waste water discharges on streamflow quality, using water-quality and stream-discharge data provided by the Pueblo Area Council of Governments. Selected results for carbonaceous biochemical oxygen demand and total ammonia from three simulations illustrate the capability of the model. (USGS)

Colorado↗

USGS1980

Waste-assimilation capacity of the Arkansas River in Pueblo County, Colorado, as it relates to water-quality guidelines and stream classification

The waste-assimilation capacity of a 42-mile reach of the Arkansas River in Pueblo County, Colo., was evaluated using a one-dimensional steady-state water-quality model. The model was calibrated and verified using hydraulic and water-quality data collected in 1976 and 1979. The water-quality con-stituents modeled were 5-day carbonaceous biochemical oxygen demand, total organic nitrogen, total ammonia, total nitrite, total nitrate, and dissolved oxygen. Model calibration was acceptable for all constituents except total organic nitrogen, and verification was acceptable for all constituents except total organic nitrogen and total nitrite. A relationship between nonionized and total ammonia was defined to provide simulation capability for nonionized ammonia. The model was used to simulate the water-quality effects of 63 combinations of wastewater treatment. The water-quality effects were evaluated with respect to water-quality guidelines that may be applied based on possible stream-use classifications. Model simulations were based on a 7-day low flow with a 10-year recurrence interval that occurs between August 15 and October 15 and on a winter low-flow period that occurs as a result of upstream storage of water. The mixing zone downstream from the Pueblo Wastewater Treatment Plant outfall was evaluated to determine where the water-quality guidelines should apply for the model simulations. Complete lateral mixing of the effluent from the Pueblo Wastewater Treatment Plant occurred 2.7 river miles downstream from the outfall. Model simulations indicated a water-quality guideline of 0.06 milligram per liter nonionized ammonia nitrogen would be exceeded at the end of the mixing zone for Q7,10 conditions with secondary treatment at the Pueblo Wastewater Treatment Plant and a projected effluent discharge for the year 2000, and that a water-quality guideline of 0.5 milligram per liter total nitrite nitrogen would be exceeded for winter conditions and the same waste-water-treatment possibility. Wastewater-treatment possibilities with a pro-jected discharge for the year 2000 which would result in both water-quality guidelines being met include land application of treated effluent and advanced secondary treatment at the Pueblo Wastewater Treatment Plant with conversion of ammonia to nitrate to result in an effluent total ammonia nitrogen concentration of 5.4 to 10.6 milligrams per liter, depending on the quality of effluent from the downstream discharge from the CF&I Steel Corp. Model simulations also included an evaluation of flow augmentation necessary to meet a water-quality guideline of 0.06 milligram per liter non-ionized ammonia nitrogen. The evaluation was made for the n,7,10 period, secondary treatment at the Pueblo Wastewater Treatment Plant with a projected discharge for the year 2000, and effluent water quality at a downstream discharge which could contain twice the estimated ammonia concentration allowable for best available technology treatment for the iron and steel industry. The flow augmentation necessary to meet the water-quality guideline, based on the model simulations, is approximately 140 cubic feet per second.

Colorado↗