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Patrick Edelmann

Publications and source records attributed to Patrick Edelmann.

At least 19 recordsLinked to original sources
USGS2007

Characterization of stormflows and wastewater treatment-plant effluent discharges on water quality, suspended sediment, and stream morphology for Fountain and Monument Creek watersheds, Colorado, 1981-2006

In 1998, the U.S. Geological Survey, in cooperation with Colorado Springs City Engineering, began a study of the Fountain and Monument Creek watersheds to characterize water quality and suspended-sediment conditions in the watershed for different flow regimes, with an emphasis on characterizing water quality during storm runoff. Water-quality and suspended-sediment samples were collected in the Fountain and Monument Creek watersheds from 1981 through 2006 to evaluate the effects of stormflows and wastewater-treatment effluent on Fountain and Monument Creeks in the Colorado Springs, Colorado, area. Water-quality data were collected at 11 sites between 1981 and 2001, and 14 tributary sites were added in 2003 to increase spatial coverage and characterize water quality throughout the watersheds. Suspended-sediment samples collected daily at 7 sites from 1998 through 2001, 6 sites daily from 2003 through 2006, and 13 tributary sites intermittently from 2003 through 2006 were used to evaluate the effects of stormflow on suspended-sediment concentrations, discharges, and yields. Data were separated into three flow regimes: base flow, normal flow, and stormflow. Stormflow concentrations from 1998 through 2006 were compared to Colorado acute instream standards and, with the exception of a few isolated cases, did not exceed water-quality standards for inorganic constituents that were analyzed. However, stormflow concentrations of both fecal coliform and Escherichia coli (E. coli) frequently exceeded water-quality standards during 1998 through 2006 on main-stem and tributary sites by more than an order of magnitude. There were two sites on Cottonwood Creek, a tributary to Monument Creek, with elevated concentrations of dissolved nitrite plus nitrate: site 07103985 (TbCr), a tributary to Cottonwood Creek and site 07103990 (lower_CoCr), downstream from site 07103985 (TbCr), and near the confluence with Monument Creek. During base-flow and normal-flow conditions, the median concentrations of dissolved nitrite plus nitrate ranged from 5.1 to 6.1 mg/L and were 4 to 7 times larger than concentrations at the nearest upstream site on Monument Creek, site 07103970 (MoCr_Woodmen). The source of these larger dissolved nitrite plus nitrate concentrations has not been identified, but the fact that all measurements had elevated dissolved nitrite plus nitrate concentrations indicates a relatively constant source. Most stormflow concentrations of dissolved trace elements were smaller than concentrations from base-flow or normal-flow samples. However, median concentrations of total arsenic, copper, lead, manganese, nickel, and zinc generally were much larger during periods of stormflow than during base flow or normal flow. Concentrations of dissolved and total copper, total manganese, total nickel, dissolved and total selenium, and dissolved and total zinc ranged from 3 to 27 times larger at site 07103707 (FoCr_8th) than site 07103700 (FoCr_Manitou) during base flow, indicating a large source of trace elements between these two sites. Both of these sites are located on Fountain Creek, upstream from the confluence with Monument Creek. The likely source area is Gold Hill Mesa, a former tailings pile for a gold refinery located just upstream from the confluence with Monument Creek, and upstream from site 07103707 (FoCr_8th). Farther downstream in Fountain Creek, stormflow samples for total copper, manganese, lead, nickel, and zinc were larger at the downstream site near the city of Security, site 07105800 (FoCr_Security), than at the upstream site near Janitell Road, site 07105530 (FoCr_Janitell), compared with other main-stem sites and indicated a relatively large source of these metals between the two sites. Nitrogen, phosphorus, and trace-element loads substantially increased during stormflow. Suspended-sediment concentrations, discharges, and yields associated with stormflow were significantly larger than those associated with normal flow. The April through October cumulative suspended-sediment discharges and streamflows were largest in 1999 and smallest in 2002. Although large spatial variations in suspended-sediment yields occurred during normal flows, the suspended-sediment yields associated with stormflow generally were more than 10 times larger than the suspended-sediment yields that occurred during normal flow. The largest suspended-sediment yields occurred at sites on streams located in the Colorado Piedmont that drain to Fountain and Monument Creeks from the east. Minimum streamflows at all sites have the capacity to transport coarse sand and gravel, and maximum streamflows at some sites have the capacity to transport coarse gravel to cobble-size material. Channel downcutting is the predominant channel-forming process. Wastewater treatment-plant discharge increased streamflow and transport capacity, resulting in a shift in median bed-material size from fine to medium gravel.

Colorado↗
USGS2005

Variability of differences between two approaches for determining ground-water discharge and pumpage, including effects of time trends, Lower Arkansas River Basin, southeastern Colorado, 1998-2002

In the mid-1990s, the Colorado Division of Water Resources (CDWR) adopted rules governing measurement of tributary ground-water pumpage for the Arkansas River Basin. The rules allowed ground-water pumpage to be determined using one of two approaches?power conversion coefficient (PCC) or totalizing flowmeters (TFM). In addition, the rules allowed a PCC to be applied to the electrical power usage up to 4 years in the future to estimate ground-water pumpage. As a result of concerns about potential errors in applying the PCC approach forward in time, a study was done by the U.S. Geological Survey, in cooperation with CDWR and Colorado Water Conservation Board, to evaluate the variability in differences in pumpage between the two approaches, including the effects of time trends. This report compared measured ground-water pumpage using TFMs to computed ground-water pumpage using PCCs by developing statistical models of relations between explanatory variables, such as site, time, and pumping water level, and dependent variables, which are based on discharge, PCC, and pumpage. When differences in pumpage (diffP) were computed using PCC measurements and power consumption for the same year (1998-2002), the median diffP, depending on the year, ranged from +0.1 to -2.9 percent; the median diffP for the entire period was -1.5 percent. However, when diffP was computed using PCC measurements applied to the next year's power consumption, the median diffP was -0.3 percent; and when PCC measurements were applied 2, 3, or 4 years into the future, median diffPs were +1.8 percent for a 2-year forward lag and +5.3 percent for a 4-year forward lag, indicating that pumpage computed with the PCC approach, as generally applied under the ground-water pumpage measurement rules by CDWR, tended to overestimate pumpage as compared to pumpage using TFMs when PCC measurement was applied to future years of measured power consumption. Analyses were done to better understand the causes of the time trend; an estimate of the overall trend with time (uncorrected for pumping water-level changes) yielded a trend of about 2.2 percent per lag year for diffP. A separate analysis that incorporated a surface-water diversion term in the statistical model rendered the time-trend term insignificant, indicating that the time trend in the models served as a surrogate for other variables, some of which reflect underlying hydrologic conditions. A more precise explanation of the potential causes of the time trend was not obtained with the available data. However, the model results with the surface-water diversion term indicate that much of the trend of 2.2 percent per lag year in diffP resulted from applying a PCC to estimate pumpage under hydrologic conditions different from those under which the PCC was measured. Although there is no evidence to conclude that the upward time trend determined in the data for this 5-year period would hold in the future, historical static ground-water levels in the study area generally have exhibited small variations over multidecadal time scales. Therefore, the approximately 2 percent per lag year trend determined in these data is expected to be a reasonable guideline for estimating potential errors in the PCC approach resulting from temporally varying hydrologic conditions between time of PCC measurement and pumpage estimation. Comparisons also were made between total, or aggregated, pumpage for a network of wells as computed by the PCC approach and the TFM approach. For 100 wells and a lag of 4 years between PCC measurement and pumpage estimation, there was a 95-percent probability that the difference between total network pumpage measured by the PCC approach and that measured using a TFM would be between 5.2 and 14.4 percent. These estimates were based on a bias of 2.2 percent per lag year estimated for the period 1998-2002 during which hydrologic conditions were known to have changed. Using the same assumptions, the estimated d

Scientific Investigations Report↗
USGS2002

Evaluation of water quality, suspended sediment, and stream morphology with an emphasis on effects of stormflow on Fountain and Monument Creek basins, Colorado Springs and vicinity, Colorado, 1981 through 2001

This report documents water quality and suspended sediment with an emphasis on evaluating the effects of stormflow on Fountain Creek Basin in the vicinity of Colorado Springs, Colorado. Water-quality data collected at 11 sites between 1981 and 2001 were used to evaluate the effects of stormflow on water quality. Suspended-sediment data collected at seven sites from 1998 through 2001 were used to evaluate effects of stormflow on suspended-sediment concentrations, discharges, and yields. Data were separated into three flow regimes: base flow, normal flow, and stormflow. A comparison of stormwater-quality concentrations measured between 1981 and 2001 to Colorado acute instream standards indicated that, except for isolated occurrences, stormwater quality met acute instream standards. At several sites, 5-day biochemical oxygen demand, fecal coliform, and selected nutrient concentrations tended to be highest during stormflow and lowest during base flow. Dissimilar to the other nutrients, dissolved nitrite plus nitrate concentrations generally were highest during base flow and lowest during stormflow. Most dissolved trace-element concentrations associated with stormflow decreased or showed little change compared to base flow. However, median concentrations of total copper, iron, lead, nickel, manganese, and zinc for stormflow samples generally were much larger than nonstorm samples. The substantially larger concentrations of total copper, iron, lead, nickel, manganese, and zinc measured at site 5800 during stormflow as compared to other sites indicates a relatively large source of these metals in the reach between sites 5530 and 5800. Semi-volatile organic compounds in samples collected during stormflow were detected relatively infrequently at the four sites monitored; however, analysis of pesticide data collected during stormflow showed a relatively frequent detection of pesticides at low levels. Nitrogen, phosphorus, and particulate trace-element loads substantially increased during stormflow. Suspended-sediment concentrations, discharges, and yields associated with stormflow were significantly greater than during normal flow. Depending on the site and year, suspended-sediment concentrations associated with storm-flow generally were 3 to10 times greater than concentrations measured during normal flow, and suspended-sediment discharges were usually more than 10 times greater during stormflow. The April through October cumulative suspended-sediment discharges and streamflows were largest in 1999 at all sites. Although large spatial variations in suspended-sediment yields occurred during normal flows, the suspended-sediment yields associated with stormflow generally were more than 10 times greater than the suspended-sediment yields that occurred during normal flow. The smallest suspended-sediment yields generally were less than 1 ton per day per square mile during stormflow. The largest suspended-sediment yields occurred at sites located in the Cottonwood Creek Basin and were greater than 10 tons per day per square mile.

Colorado↗
USGS2002

Evaluation of water quality, suspended sediment, and stream morphology with an emphasis on effects of stormwater on Fountain and Monument Creek basins, Colorado Springs and vicinity, Colorado, 1981-2001

This report documents water quality and suspended sediment with an emphasis on evaluating the effects of stormflow on Fountain Creek Basin in the vicinity of Colorado Springs, Colorado. Water-quality data collected at 11 sites between 1981 and 2001 were used to evaluate the effects of stormflow on water quality. Suspended-sediment data collected at seven sites from 1998 through 2001 were used to evaluate effects of stormflow on suspended-sediment concentrations, discharges, and yields. Data were separated into three flow regimes: base flow, normal flow, and stormflow. A comparison of stormwater-quality concentrations measured between 1981 and 2001 to Colorado acute instream standards indicated that, except for isolated occurrences, stormwater quality met acute instream standards. At several sites, 5-day biochemical oxygen demand, fecal coliform, and selected nutrient concentrations tended to be highest during stormflow and lowest during base flow. Dissimilar to the other nutrients, dissolved nitrite plus nitrate concentrations generally were highest during base flow and lowest during stormflow. Most dissolved trace-element concentrations associated with stormflow decreased or showed little change compared to base flow. However, median concentrations of total copper, iron, lead, nickel, manganese, and zinc for stormflow samples generally were much larger than nonstorm samples. The substantially larger concentrations of total copper, iron, lead, nickel, manganese, and zinc measured at site 5800 during stormflow as compared to other sites indicates a relatively large source of these metals in the reach between sites 5530 and 5800. Semi-volatile organic compounds in samples collected during stormflow were detected relatively infrequently at the four sites monitored; however, analysis of pesticide data collected during stormflow showed a relatively frequent detection of pesticides at low levels. Nitrogen, phosphorus, and particulate trace-element loads substantially increased during stormflow. Suspended-sediment concentrations, discharges, and yields associated with stormflow were significantly greater than during normal flow. Depending on the site and year, suspended-sediment concentrations associated with storm-flow generally were 3 to10 times greater than concentrations measured during normal flow, and suspended-sediment discharges were usually more than 10 times greater during stormflow. The April through October cumulative suspended-sediment discharges and streamflows were largest in 1999 at all sites. Although large spatial variations in suspended-sediment yields occurred during normal flows, the suspended-sediment yields associated with stormflow generally were more than 10 times greater than the suspended-sediment yields that occurred during normal flow. The smallest suspended-sediment yields generally were less than 1 ton per day per square mile during stormflow. The largest suspended-sediment yields occurred at sites located in the Cottonwood Creek Basin and were greater than 10 tons per day per square mile.

Water-Resources Investigations Report↗
USGS2002

Sources of metal loads to the Alamosa River and estimation of seasonal and annual metal loads for the Alamosa River Basin, Colorado, 1995-97

Metal contamination in the upper Alamosa River Basin has occurred for decades from the Summitville Mine site, from other smaller mines, and from natural, metal-enriched acidic drainage in the basin. In 1995, the need to quantify contamination from various source areas in the basin and to quantify the spatial, seasonal, and annual metal loads in the basin was identified. Data collection occurred from 1995 through 1997 at numerous sites to address data gaps. Metal loads were calculated and the percentages of metal load contributions from tributaries to three risk exposure areas were determined. Additionally, a modified time-interval method was used to estimate seasonal and annual metal loads in the Alamosa River and Wightman Fork. Sources of dissolved and total-recoverable aluminum, copper, iron, and zinc loads were determined for Exposure Areas 3a, 3b, and 3c. Alum Creek is the predominant contributor of aluminum, copper, iron, and zinc loads to Exposure Area 3a. In general, Wightman Fork was the predominant source of metals to Exposure Area 3b, particularly during the snowmelt and summer-flow periods. During the base-flow period, however, aluminum and iron loads from Exposure Area 3a were the dominant source of these metals to Exposure Area 3b. Jasper and Burnt Creeks generally contributed less than 10 percent of the metal loads to Exposure Area 3b. On a few occasions, however, Jasper and Burnt Creeks contributed a substantial percentage of the loads to the Alamosa River. The metal loads calculated for Exposure Area 3c result from upstream sources; the primary upstream sources are Wightman Fork, Alum Creek, and Iron Creek. Tributaries in Exposure Area 3c did not contribute substantially to the metal load in the Alamosa River. In many instances, the percentage of dissolved and/or total-recoverable metal load contribution from a tributary or the combined percentage of metal load contribution was greater than 100 percent of the metal load at the nearest downstream site on the Alamosa River. These data indicate that metal partitioning and metal deposition from the water column to the streambed may be occurring in Exposure Areas 3a, 3b, and 3c. Metals that are deposited to the streambed probably are resuspended and transported downstream during high streamflow periods such as during snowmelt runoff and rainfall runoff. Seasonal and annual dissolved and total recoverable aluminum, copper, iron, and zinc loads for 1995-97 were estimated for Exposure Areas 1, 2, 3a, 3b, and 3c. During 1995-97, many tons of metals were transported annually through each exposure area. Generally, the largest estimated annual total recoverable metal mass for most metals was in 1995. The smallest estimated annual total-recoverable metal mass was in 1996, which also had the smallest annual streamflow. In 1995 and 1997, more than 60 percent of the annual total-recoverable metal loads generally was transported through each exposure area during the snowmelt period. A comparison of the estimated storm load at each site to the corresponding annual load indicated that storms contribute less than 2 percent of the annual load at any site and about 5 to 20 percent of the load during the summer-flow period.

Colorado↗
USGS1999

Comparison of two approaches for determining ground-water discharge and pumpage in the lower Arkansas River Basin, Colorado, 1997-98

In March 1994, the Colorado Division of Water Resources (CDWR) adopted “Rules Governing the Measurement of Tributary Ground Water Diversions Located in the Arkansas River Basin” (Office of the State Engineer, 1994); these initial rules were amended in February 1996 (Office of the State Engineer, 1996). The amended rules require users of wells that divert tributary ground water to annually report the water pumped monthly by each well. The rules allow a well owner to report the pumpage measured by a totalizing flowmeter (TFM) or pumpage determined from electrical power data and a power conversion coefficient (PCC) (Hurr and Litke, 1989). Opinions by representatives of the State of Kansas, presented before the Special Master hearing a court case [State of Kansas v. State of Colorado, No. 105 Original (1996)] concerning post-Compact well pumping, stated that the PCC approach does not provide the same level of accuracy and reliability as a TFM when used to determine pumpage. In 1997, the U.S. Geological Survey (USGS), in cooperation with the CDWR, began a 2-year study to compare ground-water pumpage estimates made using the TFM and the PCC approaches. The study area was along the Arkansas River between Pueblo, Colorado, and the Colorado-Kansas State line (fig. 1). The two approaches for estimating ground-water discharge and pumpage were compared for more than 100 wells completed in the alluvial aquifer of the Arkansas River Basin. The TFM approach uses an inline flowmeter to directly measure instantaneous discharge and the total volume of water pumped at a well. The PCC approach uses electrical power consumption records and a power conversion coefficient to estimate the pumpage at ground-water wells. This executive summary describes the results of the comparison of the two approaches. Specifically, (1) the differences in instantaneous discharge measured with three portable flowmeters and measured with an inline TFM are evaluated, and the statistical differences in paired instantaneous discharge between the two approaches are determined; (2) short- and long-term variations in the PCC’s are presented; (3) differences in pumpage between the two approaches are evaluated, and the statistical differences in pumpage between the two approaches are determined; (4) potential sources of discrepancy between pumpage estimates are discussed; and (5) differences in total network pumpage using the two approaches are presented. During the irrigation seasons of 1997 and 1998, instantaneous discharge and electrical power demand were measured at randomly selected wells to determine PCC’s. At more than 100 wells, the PCC’s determined during the 1998 season were applied to total electrical power consumption data that was recorded between the initial and final readings at each network well site in 1998 to estimate total ground-water pumpage. At each site, an inline TFM was installed in a full-flowing, acceptable test section of pipe on the discharge side of the pump where the measurement of discharge was made. Measurements of instantaneous ground-water discharge also were made using three different types of portable flowmeters. The average velocity multiplied by the cross-sectional area of the discharge pipe was used to compute the discharge in gallons per minute. Whenever possible, discharge measurements were made at each network site using all three types of portable flowmeters.

Colorado↗
USGS1997

Physical and chemical characteristics of Terrace Reservoir, Conejos County, Colorado, May 1994 through May 1995

Terrace Reservoir receives drainage of low-pH, metal-enriched water from mineralized areas, including the Summitville Mine, within the Alamosa River Basin. Drainage from the Summitville Mine has contributed a substantial part of the metal load to Terrace Reservoir. From May 1994 through May 1995, a study was done by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to evaluate the physical and chemical characteristics of Terrace Reservoir. Terrace Reservoir was thermally stratified from about mid-May through August 1994. Thermal stratification was absent from September\x111994through March 1995. During periods of stratification, underflow of the Alamosa River was predominant, and residence times of the underflow were shortened by 40 to 75\x11percent of the theoretical residence times for a well-mixed reservoir. Transport and deposition of suspended solids in Terrace Reservoir varied spatially and temporally. Most of the suspended solids were deposited in Terrace Reservoir. The concentration of dissolved oxygen in the reservoir varied little spatially or temporally and generally was within a few tenths of the dissolved-oxygen concentration of the inflow. The pH of water in the reservoir generally ranged from about 4.0 to about 7.0, depending on date, depth, and location. The largest pH values were measured during May. A markeddecrease of about 1.5\x11pH units occurred at site T5 in the reservoir about mid-June. The pH of the reservoir remained at or below 5.5 from mid-June through November. Dissolved-metal concentrations varied spatially and temporally in response to several factors, which included inflow characteristics, reservoir stratification and mixing, inflow-routing and flow-through patterns, residence times, sedimentation, dissolved oxygen, and pH.Inflow chemistry is the dominant controlling factor of metal chemistry within Terrace Reservoir.During periods of stratification, large vertical variations in metal concentrations occurred. The highest metal concentrations in the reservoir generally were measured in the hypolimnion between June and August. During June, epilimnetic water of the reservoir had pH values greater than 6.0, and metal concentrations were lower than hypolimnetic concentrations. In the hypolimnion, pH values were less than 5.5. The difference between the chemistry of the epilimnion and the hypolimnion was due to differences in flow routing and residence times of water in those respective layers. The dissolved-metal concentrations were larger during July and August than during June.During September, small vertical variations in metalconcentrations occurred, and the dissolved-metal concentrations were nearly equivalent to the average August metal concentrations, indicatingthat the metal concentrations measured during September resulted largely from reservoir mixing.During March, the largest metal concentrationsoccurred in the epilimnion, where pH was about 5.5; in the hypolimnion, where the pH was about 6.0, dissolved-metal concentrations were substantially lower and reflected inflow concentrations.

Colorado↗
USGS1996

Physical and chemical characteristics of Terrace Reservoir, Conejos County, Colorado, May 1994 through May 1995; interim report

Terrace Reservoir receives drainage of low-pH, metal-enriched water from mineralized areas, including the Summitville Mine, within the Alamosa River Basin. Drainage from the Summitville Mine has contributed a substantial part of the metal load to Terrace Reservoir. From May 1994 through May 1995, a study was done by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to evaluate the physical and chemical characteristics of Terrace Reservoir. Terrace Reservoir was thermally stratified from about mid-May through August 1994. Thermal stratification was absent from September\x111994through March 1995. During periods of stratification, underflow of the Alamosa River was predominant, and residence times of the underflow were shortened by 40 to 75\x11percent of the theoretical residence times for a well-mixed reservoir. Transport and deposition of suspended solids in Terrace Reservoir varied spatially and temporally. Most of the suspended solids were deposited in Terrace Reservoir. The concentration of dissolved oxygen in the reservoir varied little spatially or temporally and generally was within a few tenths of the dissolved-oxygen concentration of the inflow. The pH of water in the reservoir generally ranged from about 4.0 to about 7.0, depending on date, depth, and location. The largest pH values were measured during May. A markeddecrease of about 1.5\x11pH units occurred at site T5 in the reservoir about mid-June. The pH of the reservoir remained at or below 5.5 from mid-June through November. Dissolved-metal concentrations varied spatially and temporally in response to several factors, which included inflow characteristics, reservoir stratification and mixing, inflow-routing and flow-through patterns, residence times, sedimentation, dissolved oxygen, and pH. Inflow chemistry is the dominant controlling factor of metal chemistry within Terrace Reservoir. During periods of stratification, large vertical variations in metal concentrations occurred. The highest metal concentrations in the reservoir generally were measured in the hypolimnion between June and August. During June, epilimnetic water of the reservoir had pH values greater than 6.0, and metal concentrations were lower than hypolimnetic concentrations. In the hypolimnion, pH values were less than 5.5. The difference between the chemistry of the epilimnion and the hypolimnion was due to differences in flow routing and residence times of water in those respective layers. The dissolved-metal concentrations were larger during July and August than during June. During September, small vertical variations in metal concentrations occurred, and the dissolved-metal concentrations were nearly equivalent to the average August metal concentrations, indicatingthat the metal concentrations measured during September resulted largely from reservoir mixing.During March, the largest metal concentrationsoccurred in the epilimnion, where pH was about 5.5; in the hypolimnion, where the pH was about 6.0, dissolved-metal concentrations were substantially lower and reflected inflow concentrations.

Colorado↗
USGS1996

Assessment of metal transport into and out of Terrace Reservoir, Conejos County, Colorado, April 1994 through March 1995

Terrace Reservoir is the primary source of water for crops and livestock in the southwestern part of the San Luis Valley in southern Colorado. Mining activities have occurred in the basin for more than 100 years, and substantial mining of gold has occurred intermittently at the Summitville Mine. Historically, the Summitville Mine site has produced highly acidic, metal-enriched water that drained from the mine site into Wightman Fork and flowed to the Alamosa River and Terrace Reservoir. In 1994, a study was begun as part of risk-assessment and remediation efforts and to evaluate metal transport into and out of Terrace Reservoir. During the study period, the pH immediately upstream from Terrace Reservoir ranged from 4.3 to 7.8. The highest pH occurred during the pre-peak snowmelt period; the lowest pH occurred during storm runoff during summer. Downstream from Terrace Reservoir, the pH ranged from 4.6 to 7.6. The highest pH occurred during the pre-peak snowmelt period, and the lowest pH occurred during summer in mid-July. A comparison of the streamflow hydrographs upstream and downstream from Terrace Reservoir indicated that there was only a small difference between the annual volume of water that entered the reservoir and the annual volume of water that was released from the reservoir. Large spatial and temporal variations in concentrations of the metals of concern occurred during the study. The median and maximum concentrations of dissolved and total aluminum, iron, copper, cadmium, manganese, and zinc were larger upstream from the reservoir than downstream from the reservoir. The largest concentrations of dissolved aluminum, iron, copper, cadmium, manganese, and zinc generally occurred between mid-June and November. Throughout the study, aluminum was transported into the reservoir predominantly in the particulate or suspended form. Downstream from the reservoir, the suspended-aluminum fraction was predominant only during the pre-peak snowmelt and peak snowmelt periods. The temporal variations in the percentage of dissolved and suspended fraction of iron and copper downstream from Terrace Reservoir were similar to the temporal variations that occurred upstream from the reservoir. During the study period, cadmium, manganese, and zinc generally were transported into and out of the reservoir predominantly in the dissolved form. Metal loads varied considerably as a result of changes in streamflow or changes in metal concentrations, or both. The largest daily loads of aluminum, iron, and manganese were transported into and out of Terrace Reservoir during the peak snowmelt period. The reservoir was a sink for an estimated 294 tons of aluminum and 596 tons of iron. However, about 68.5 tons of total aluminum and about 194 tons of total iron were transported out of the reservoir during the study period. During the study period, about 22 tons of total copper remained in the reservoir, and 39 tons was transported downstream from the reservoir. About 47 tons of total manganese and 18 tons of total-zinc loads were transported out of the reservoir; the reservoir was a sink for only a small fraction of total-manganese and -zinc.

Colorado↗
USGS1994

Physical, chemical, and biological characteristics of Pueblo Reservoir, Colorado, 1985-89

Physical, chemical, and biological characteristics of Pueblo Reservoir are described on the basis of data collected from spring 1985 through fall 1989. Also included are discussions of water quality of the upper Arkansas River Basin and the reservoir as they relate to reservoir operations. Pueblo Reservoir is a multipurpose, main-stem reservoir on the Arkansas River about 6 miles west of Pueblo, Colorado. At the top of its conservation pool, the reservoir is more than 9 miles long and ranges in depth from a few feet at the inflow to about 155 feet at the dam. Pueblo Reservoir derives most of its contents from the Arkansas River, which comprises native and transmountain flow. With respect to water temperature, the reservoir typically was well mixed to weakly stratified during the early spring and gradually became strongly stratified by May. The strong thermal stratification and underflow of the Arkansas River generally persisted into August, at which time the reservoir surface began to cool and the reservoir subsequently underwent fall turnover. Following fall turnover, the reservoir was stratified to some degree in the shallow upstream part and well mixed in the deeper middle and downstream parts. Reservoir residence times were affected by the extent of stratification present. When the reservoir was well mixed, residence times were as long as several months. During the summer when the reservoir was strongly stratified, reservoir releases were large, and when underflow was the prevalent flow pattern of the Arkansas River, reservoir residence times were as short as 30 days. Most particulate matter settled from the water column between the inflow and a distance of about 5 miles downstream. On occasions of large streamflows and sediment loads from the Arkansas River, particulate matter was transported completely through the reservoir. Water transparency, as measured with a Secchi disk, increased in a downstream direction from the reservoir inflow. The increase probably was a result of sediment settling from the water column in the upstream part of the reservoir. Secchi-disk depths in December through April were larger than those in May through November. Secchi-disk depths were small between May through August as inflow sediment loads and reservoir biomass increased. In the fall, Secchi-disk depths remained small possibly as the result of resuspension of sediment and detritus within the water column. Dissolved-oxygen concentrations generally were near supersaturation near the reservoir surface. Dissolved-oxygen concentrations decreased with increasing depth. On several occasions during the summer, dissolved oxygen became completely depleted in the hypolimnion of the downstream part of the reservoir. The most extensive period of anoxia that was measured was in August 1988; the bottom 12 to 30 feet of the downstream end of the reservoir was anoxic. Fall turnover typically resulted in well-oxygenated conditions throughout the water column from September or October through the spring. Values of pH ranged from 7.5 to 9.0 and typically were largest near the surface and decreased with depth. Dissolved-solids concentrations in the reservoir primarily are affected by dissolved solids in the inflow from the Arkansas River. Concentrations are largest during periods of decreased streamflows, September through April, and decrease with increasing streamflows in May through August. The median dissolved-solids concentration increased from 224 milligrams per liter at the inflow to 262 milligrams per liter at the outflow. However, a statistical analysis of dissolved solids indicated the apparent increase in dissolved-solids concentrations between the inflow and outflow was not significant. Calcium, sulfate, and bicarbonate are the major dissolved ions in Pueblo Reservoir. Concentrations of the major nutrients, nitrogen and phosphorus, varied within the reservoir because of settling of particulate matter, uptake by phytoplankton near the reservoir surface, and releases from the reservoir bottom sediments. Phosphorus was indicated to be a potentially growth-limiting nutrient in the reservoir because of its relatively small concentrations. During 1986 and 1987, the reservoir retained about 35 percent (359 tons) of the total nitrogen load and about 83 percent (203 tons) of the total phosphorus load. Settling of particulate matter from the water column and uptake by phytoplankton are the major nutrient sinks in the reservoir. Barium, iron, manganese, and zinc were the major trace elements in Pueblo Reservoir. Traceelement concentrations in the reservoir varied because of seasonality of trace-element concentrations in the Arkansas River, settling of particulate matter, and flux of trace elements from the bottom sediments. The aquatic-life standard in Pueblo Reservoir for total-recoverable iron (1,000 micrograms per liter) and the public water-supply standard for dissolved manganese (50 micrograms per liter) were exceeded on several occasions during the summer. Elevated concentrations of totalrecoverable iron and dissolved manganese in the Arkansas River during summer runoff contributed to exceedances in the upper part of the reservoir. Flux of manganese from the reservoir bottom sediments during periods of low or depleted dissolved-oxygen concentrations contributed to exceedances in the deeper, downstream parts of the reservoir. Concentrations of lead, mercury, and zinc were elevated in the reservoir bottom sediments and may be the result of metal-mine drainage in the upper Arkansas River Basin. Median concentrations of total organic carbon ranged from 3.1 to 4.5 milligrams per liter in May through September and from 2.5 to 3.5 milligrams per liter in October through April. Totalorganic-carbon concentrations in the reservoir were largest in the summer when streamflows and total-organic-carbon concentrations are largest in the Arkansas River. Total-organic-carbon concentrations in the reservoir decrease downstream from the reservoir inflow because of settling of particulate organic carbon. Levels of gross-alpha and gross-beta radioactivity generally were relatively low. In 7 of 31 samples collected, dissolved gross-alpha radioactivity, as natural uranium, exceeded 5 picocuries per liter, the level at which additional radiochemical analyses are recommended for drinking-water supplies. Potential sources of uranium in Pueblo Reservoir include weathering of exposed uranium ore deposits in the upper Arkansas River Basin and a uranium milling operation near Canon City. Phytoplankton densities and biovolumes measured during the winter, spring, and fall generally were indicative of a small to moderate algal biomass. Phytoplankton production tended to be largest during the summer. During the summer, phytoplankton densities and biovolumes generally were indicative of a moderate to large algal biomass. However, excessive algal production and biomass periodically occurred during the spring, summer, and fall. Three species of phytoplankton that are specifically associated with taste-and-odor problems in drinking water were identified on several occasions in water samples collected from Pueblo Reservoir. Reservoir operations and hydrodynamics can substantially affect processes that affect reservoir water quality. Stratification, underflow, and hypolimnetic withdrawals affect concentrations of dissolved solids, availability of nutrients, and concentrations of metals in the reservoir. Stratification impedes the mixing of epilimnetic and hypolimnetic waters, and the prevalent underflow that occurs during the summer results in a decrease in the potential dilution of inflowing river water with reservoir water. The underflow also decreases the maximum available nutrient load to the euphotic zone, which can, in turn, offset the maximum algal growth potential. Increased dissolved-solids, nutrient, and metal concentrations that occur in the hypolimnion during the summer are partially offset by hypolimnetic withdrawals.

Colorado↗
USGS1989

Reconnaissance of water quality of Pueblo Reservoir, Colorado: May through December 1985

Pueblo Reservoir is the farthest upstream, main-stream reservoir constructed on the Arkansas River and is located in Pueblo County approximately 6 miles upstream from the city of Pueblo, Colorado. During the 1985 sampling period, the reservoir was stratified, and underflow from the Arkansas River occurred that resulted in stratification with respect to specific conductance. Concentrations of dissolved solids decreased markedly below the thermocline during June. Later in the summer, dissolved-solids concentrations increased substantially below the thermocline. Substantial depletion of dissolved oxygen occurred near the bottom of the reservoir. The dissolved oxygen minimum of 0.1 mg/L occurred during August near the reservoir bottom at transect 7 (near the dam). The average total-inorganic-nitrogen concentration near the reservoir surface was about 0.2 mg/L; near the reservoir bottom, the average concentration was about 0.3 mg/L. Concentrations of total phosphorus ranged from less than 0.01 to 0.05 mg/L near the reservoir surface, and from less than 0.01 to 0.22 mg/L near the reservoir bottom. At transect 2 (about 7 miles upstream from the dam) near the bottom of the reservoir, concentrations of total iron exceeded aquatic-life standards, and dissolved-manganese concentrations exceeded standards for public water supply. Diatoms, green algae, blue-green algae, and cryptomonads comprised the majority of phytoplankton in Pueblo Reservoir in 1985. The maximum average of 41,000 cells/ml occurred in July. Blue-green algae dominated from June to September; diatoms were the dominant group of algae in October. The average concentrations of phytoplankton decreased from July to October.

Colorado↗
USGS1986

A reconnaissance water-quality appraisal of the Fountain Creek alluvial aquifer between Colorado Springs and Pueblo, Colorado, including trace elements and organic constituents

This report describes the hydrology and chemical quality of water in the stream-aquifer system along Fountain Creek and relates groundwater quality to land use, water use, and wastewater discharges. The alluvial aquifer, which is underlain by shale bedrock, is transmissive, extensively pumped, and primarily is recharged by Fountain Creek and irrigation-return flow. Groundwater flows south about 20 ft/day, average residence time is less than 10 yr. Land use primarily is urban in the northern one-third and agricultural in the southern two-thirds of the area. Major ions, boron, iron, lithium, selenium, strontium, and uranium increased in concentration downgradient. The largest concentrations of nitrogen and detergents were in the northern end of the area because of recharge of sewage effluent in Fountain Creek. Other trace elements usually were present in concentrations less than 20 mg/L. Volatile organic compounds were detected in water from 11 of 20 wells sampled. Samples from 4 of the 20 wells were analyzed for semivolatile organics using a closed-loop stripping technique, which detected additional compounds at nanogram/L concentrations. (USGS)

Water-Resources Investigations Report↗
USGS1985

Sources of water and nitrogen to the Widefield Aquifer, southwestern El Paso County, Colorado

The Widefield aquifer near Colorado Springs, Colorado, is recharged primarily by Fountain Creek and, to a lesser extent, by infiltration and percolation of water from the land surface and from groundwater inflow. During the past 20 to 30 years, concentrations of nitrate (as nitrogen) in the Widefield aquifer have increased from 0.5 to 3.0 milligrams/L to nearly 10 milligrams/L, and occasionally exceed the drinking-water standard of 10 milligrams/L as nitrogen. During the summer of 1982, the concentrations of nitrite plus nitrate as nitrogen in water in the aquifer ranged from 3.2 to 15 milligrams/L with a mean concentration of 6.9 milligrams/L. In general, the nitrite-plus-nitrate concentrations are greatest near the north end of the aquifer, probably resulting from effluent from Colorado Springs Sewage Treatment Plant being discharged to Fountain Creek. During 1982, 93% of the total estimated 160 tons of nitrogen available to enter the Widefield aquifer was from the Colorado Springs Sewage Treatment Plant. However, a significant proportion of this nitrogen may have been lost through denitrification. (USGS)

Water-Resources Investigations Report↗
USGS1984

Effects of irrigating with wastewater on ground-water quality at Fort Carson Military Reservation golf course near Colorado Springs, Colorado

Fort Carson Military Reservation has used treatment wastewater for irrigation of the Fort Carson golf course since 1971. The effect of applied wastewater on groundwater quality at Fort Carson golf course was evaluated using water levels and water-quality data from 20 observation wells. The water-quality constituents analyzed included dissolved solids, major ions, nutrients, detergents, dissolved organic carbon, chemical and biological oxygen demand, and trace elements. Effects of the applied wastewater on ground-water quality for most constituents were obscured by large areal variations and by high concentrations of the constituents upgradient from the golf course. The sources of nitrogen observed in the ground water beneath the golf course were applied wastewater, applied fertilizer, leachate from the organic-rich shale, and from unknown upgradient sources. Nitrogen loading at the golf course from wastewater and applied fertilizer was estimated to be 18 ,900 pounds per year. After 10 years, less than 1 percent of the nitrogen applied was actually present in the ground water. Loss of nitrogen to the atmosphere as nitrous oxides, absorption, and to fixation by grass resulted in the much smaller concentrations observed in the ground water. (USGS)

Colorado↗
USGS1984

Quality of ground water in agricultural areas of the San Luis Valley, south-central Colorado

The quality of ground water in the principal agricultural areas of the San Luis Valley, south-central Colorado was evaluated using chemical analyses of water collected from 57 wells completed in the unconfined aquifer and from 25 wells completed in the confined aquifer. Ground water in both aquifers generally contains dissolved-solids concentrations of less than 500 milligrams per liter. In most areas, calcium is the principal cation in the ground water. Nitrite plus nitrate concentrations expressed as nitrogen, are generally less than 1 milligram per liter. However, the quality of ground water in certain areas may pose health and agricultural hazards. Water in the unconfined aquifer near Center contains high nitrite plus nitrate as nitrogen concentrations. The highest measured concentration in this area was 33 milligrams per liter. Water containing more than 1 milligram per liter of nitrite as nitrogen, or 10 milligrams per liter nitrate, as nitrogen, poses a potential health hazard for infants and should not be used for drinking. In addition, dissolved-solids concentration in the ground water in some areas is greater than 500 milligrams per liter and, if used for irrigation may reduce crop yields. (USGS)

Water-Resources Investigations Report↗
USGS1983

Hydrology of Area 61, Northern Great Plains and Rocky Mountain Coal Provinces, Colorado and New Mexico

Area 61 is located on the Colorado-New Mexico boundary in Huerfano and Las Animas Counties, Colorado, and Colfax County, New Mexico, and includes the Raton Mesa coal region. The 5 ,900-square-mile area is an asymmetrical structural trough bounded by the Rocky Mountains on the west and the Great Plains on the east. The area is drained by the Huerfano, Apishapa, Purgatoire, and Canadian Rivers (and their tributaries), all tributary to the Arkansas River. The principal coal-bearing formations are the Vermejo Formation of Late Cretaceous age and the Raton Formation of Late Cretaceous and Paleocene age. Much of the coal in the area is of coking quality, important to the metallurgical industry. Topographic relief in the area is greater than 8,700 feet, and this influences the climate which in turn affects the runoff pattern of area streams. Summer thunderstorms often result in flash floods. Virtually all geologic units in the region yield water. Depth to ground water ranges from land surface to 400 feet. Surface and ground water in the area contain mostly bicarbonate and sulfate ions; locally in the ground water, chloride ions predominate. Potential hydrologic problems associated with surface coal mining in the area are water-quality degradation, water-table decline, and increased erosion and sedimentation.

Open-File Report↗