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At least 1,243 records · Page 69Linked to original sources
USGS2022

The thermal landscape of the Willamette River—Patterns and controls on stream temperature and implications for flow management and cold-water salmonids

Water temperature is a primary control on the health, diversity, abundance, and distribution of aquatic species, but thermal degradation resulting from anthropogenic influences on rivers is a challenge to threatened species worldwide. In the Willamette River Basin, northwestern Oregon, spring-run Chinook salmon ( Oncorhynchus tshawytscha ) and winter-run steelhead ( O. mykiss ) are formerly abundant cold-water-adapted species that are now protected under the Endangered Species Act. Among the challenges to the health of cold-water salmonids in the Willamette River Basin, disruptions in the seasonal patterns of stream temperature imposed by 13 large, multipurpose dams on tributaries to the Willamette River, as well as temperatures routinely in excess of regulatory limits in the Willamette River Basin, are contributing factors. To better understand controls on stream temperature, the sensitivity of stream temperature to flow augmentation as a management tool for suppressing high temperatures, and the implications for threatened salmonids, this study used a two-dimensional hydrodynamic and water-quality model (CE-QUAL-W2) to investigate spatial and temporal patterns of stream temperature in the Willamette River Basin. This study focused on the upper 160.4 river miles of the Willamette River from the confluence of the Middle Fork and Coast Fork Willamette Rivers (river mile 187.2) to Willamette Falls (river mile 26.8), three representative climate years (2011, a cool and wet year; 2015, an extremely hot and dry year; and 2016, a moderately hot and dry year), and a series of flow-augmentation scenarios. Model results show that the Willamette River upstream from Willamette Falls is divisible into four characteristic “thermal reaches” with similar thermal patterns, depending on tributary input, warming rate, and the timing of thermal response. In general, the Willamette River warms downstream during spring and summer, but patterns are complex, influenced by tributary inflows, and seasonally variable. Except in cool wet years (as illustrated by 2011), modeling suggests that adversely warm conditions for spring-run Chinook salmon are extensive from June or July through August. The thermal influence of flow augmentation from dam storage on four tributaries with U.S. Army Corps of Engineers dams varies spatially along the Willamette River, seasonally, and in magnitude, depending on a range of factors like distance from the Willamette River, the temperature of dam outflow, and the thermal template of tributary reaches controlling stream temperature adjustment to environmental heat fluxes. Modeling suggests that targeted flow management (via augmentation from dam storage) can reduce the extent and duration of thermally stressful conditions for Chinook salmon for short periods, but modeling suggests that flow augmentation is limited in its ability to fundamentally alter the “thermal landscape” (the entire range of temperature variation in a river system over space and time) of the Willamette River. While this research provides general insights into the thermal landscape of the Willamette River and its sensitivity to flow management, additional investigation into the thermal landscape of tributaries downstream from U.S. Army Corps of Engineers dams, as well as the thermal management of reservoirs, storage availability, and dam outflows, would be necessary to target specific management actions for supporting specified rearing or migration conditions for spring-run Chinook salmon and other cold-water-adapted species in the Willamette River Basin.

Oregon↗
USGS2000

Suspended-sediment characteristics in the Housatonic River Basin, western Massachusetts and parts of eastern New York and northwestern Connecticut, 1994-96

Suspended-sediment concentrations, discharges, loads, and yields were determined for eight subbasins in the Housatonic River Basin in western Massachusetts, eastern New York, and northwestern Connecticut from April 1994 through March 1996. Suspended-sediment samples were collected at three continuous-record sediment stations and at four partial-record sediment stations. Suspended-sediment concentrations in samples collected during the period of study ranged from less than 0.5 to 3,400 milligrams per liter, and concurrent streamflows ranged from 0.03 to 126 cubic feet per second per square mile at the seven stations. Median suspended-sediment concentrations in samples collected at each station ranged from 7 to 61 milligrams per liter. Median streamflows during suspended-sediment sampling ranged from 1.86 to 5.88 cubic feet per second per square mile. Instantaneous suspended-sediment yields ranged from less than 0.005 to 185 tons per day per square mile, and medians ranged from 0.03 to 1.12 tons per day per square mile at the seven stations. Total suspended-sediment loads (mass) from April 1994 through March 1996 at the continuous-record sediment stations were 11,603 tons at Housatonic River near Great Barrington, 7,929 tons at Green River, and 54,347 tons at Housatonic River near Ashley Falls. Suspended-sediment load during January 1996 at the Green River station accounted for about 54 percent of the total suspended-sediment load for the Green River during the 2-year study. Suspended-sediment load on January 19 and 20, 1996, at the Green River station accounted for about 50 percent of the January 1996 suspended-sediment load, or about 27 percent of the total suspended-sediment load during the 2-year study. This large suspended-sediment transport was the result of rainfall and snowmelt on January 19 and 20, 1996--the equivalent of a 5- to 6-inch rain storm in the Green River subbasin. Total suspended-sediment loads during the 2-year study at the partial-record sediment stations were 3,052 tons at Williams River, 1,758 tons at Ironworks Brook, and 17,927 tons at Konkapot River. Suspended-sediment yields from April 1994 through March 1996 at the continuous-record sediment stations were 21 (tons/yr)/mi 2 at Housatonic River near Great Barrington, 78 (tons/yr)/mi 2 at Green River, and 58 (tons/yr)/mi 2 at Housatonic River near Ashley Falls. Suspended-sediment yields during the 2- year study at the partial-record sediment stations were 35 (tons/yr)/mi 2 at Williams River, 78 (tons/yr)/mi 2 at Ironworks Brook, and 147 (tons/yr)/mi 2 at Konkapot River. Suspended-sediment yields were estimated for two subbasins in the Housatonic River Basin--Schenob Brook at Sheffield, a partial-record sediment station, and the area adjacent to the Housatonic River between Great Barrington and Ashley Falls. The estimate of suspended-sediment yield at Schenob Brook at Sheffield of 82 (tons/yr)/mi 2 is comparable to the yield determined for the Green River and Ironworks Brook. The estimate of suspended-sediment yield for the area adjacent to the Housatonic River between Great Barrington and Ashley Falls was 395 (tons/yr)/mi 2 . This estimated suspended-sediment yield was 2.7 to 18.8 times greater than that estimated for any of the other subbasins. Several basin and land-use characteristics thought to affect suspended-sediment transport in the subbasins were compared to the suspended-sediment yields. The characteristics that seemed to affect suspended-sediment discharge were dams, which contributes to decreased yields; Hadley, Limerick, Linlithgo, Saco, and Winooski silt loam soils (high erodibility soils), which contributes to increased yields; stratified-drift deposits, which contributes to increased yields; and agricultural and open land, which contributes to increased yields. The effect of stratified-drift deposits on suspended-sediment discharge is thought to be greater when those deposits are of glaciolacustrine (generally clay, silt, and fine sand), rather than glaciofluvial (clay, silt, sand, gravel, and cobbles) origin. The silt loam soils, glaciolacustrine deposits, and agricultural and open land are interrelated, inasmuch as the silt loam soils generally are associated with glaciolacustrine deposits and agricultural activities.

Connecticut, Massachusetts, New York↗
USGS2000

Status and trends in suspended-sediment discharges, soil erosion, and conservation tillage in the Maumee River basin: Ohio, Michigan, and Indiana

The relation of suspended-sediment discharges to conservation-tillage practices and soil loss were analyzed for the Maumee River Basin in Ohio, Michigan, and Indiana as part of the U.S. Geological Survey’s National Water-Quality Assessment Program. Cropland in the basin is the largest contributor to soil erosion and suspended-sediment discharge to the Maumee River and the river is the largest source of suspended sediments to Lake Erie. Retrospective and recently-collected data from 1970–98 were used to demonstrate that increases in conservation tillage and decreases in soil loss can be related to decreases in suspended-sediment discharge from streams. Average annual water and suspended-sediment budgets computed for the Maumee River Basin and its principal tributaries indicate that soil drainage and runoff potential, stream slope, and agricultural land use are the major human and natural factors related to suspended-sediment discharge. The Tiffin and St. Joseph Rivers drain areas of moderately to somewhat poorly drained soils with moderate runoff potential. Expressed as a percentage of the total for the Maumee River Basin, the St. Joseph and Tiffin Rivers represent 29.0 percent of the basin area, 30.7 percent of the average-annual streamflow, and 9.31 percent of the average annual suspended-sediment discharge. The Auglaize and St. Marys Rivers drain areas of poorly to very poorly drained soils with high runoff potential. Expressed as a percentage of the total for the Maumee River Basin, the Auglaize and St. Marys Rivers represent 48.7 percent of the total basin area, 53.5 percent of the average annual streamflow, and 46.5 percent of the average annual suspended-sediment discharge. Areas of poorly drained soils with high runoff potential appear to be the major source areas of suspended sediment discharge in the Maumee River Basin. Although conservation tillage differed in the degree of use throughout the basin, on average, it was used on 55.4 percent of all crop fields in the Maumee River Basin from 1993–98. Conservation tillage was used at relatively higher rates in areas draining to the lower main stem from Defiance to Waterville, Ohio and at relatively lower rates in the St. Marys and Auglaize River Basins, and in areas draining to the main stem between New Haven, Ind. and Defiance, Ohio. The areas that were identified as the most important sediment-source areas in the basin were characterized by some of the lowest rates of conservation tillage. The increased use of conservation tillage was found to correspond to decreases in suspended- sediment discharge over time at two locations in the Maumee River Basin. A 49.8 percent decrease in suspended-sediment discharge was detected when data from 1970–74 were compared to data from 1996–98 for the Auglaize River near Ft. Jennings, Ohio. A decrease in suspended-sediment discharge of 11.2 percent was detected from 1970–98 for the Maumee River at Waterville, Ohio. No trends in streamflow at either site were detected over the period 1970–98. The lower rate of decline in suspended-sediment discharge for the Maumee River at Waterville, Ohio compared to the Auglaize River near Ft. Jennings, may be due to resuspension and export of stored sediments from drainage ditches, stream channels, and flood plains in the large drainage basin upstream from Waterville. Similar findings by other investigators about the capacity of drainage networks to store sediment are supported by this investigation. These findings go undetected when soil loss estimates are used alone to evaluate the effectiveness of conservation tillage. Water-quality data in combination with soil-loss estimates were needed to draw these conclusions. These findings provide information to farmers and soil conservation agents about the ability of conservation tillage to reduce soil erosion and suspended-sediment discharge from the Maumee River Basin.

Indiana, Michigan, Ohio↗
USGS2001

Surface-geophysical characterization of ground-water systems of the Caloosahatchee River basin, southern Florida

The Caloosahatchee River Basin, located in southwestern Florida, includes about 1,200 square miles of land. The Caloosahatchee River receives water from Lake Okeechobee, runoff from the watershed, and seepage from the underlying ground-water systems; the river loses water through drainage to the Gulf of Mexico and withdrawals for public-water supply and agricultural and natural needs. Water-use demands in the Caloosahatchee River Basin have increased dramatically, and the Caloosahatchee could be further stressed if river water is used to accommodate restoration of the Everglades. Water managers and planners need to know how much water will be used within the river basin and how much water is contributed by Lake Okeechobee, runoff, and ground water. In this study, marine seismic-reflection and ground-penetrating radar techniques were used as a means to evaluate the potential for flow between the river and ground-water systems. Seven test coreholes were drilled to calibrate lithostratigraphic units, their stratal geometries, and estimated hydraulic conductivities to surface-geophysical profiles. A continuous marine seismic-reflection survey was conducted over the entire length of the Caloosahatchee River and extending into San Carlos Bay. Lithostratigraphic units that intersect the river bottom and their characteristic stratal geometries were identified. Results show that subhorizontal reflections assigned to the Tamiami Formation intersect the river bottom between Moore Haven and about 9 miles westward. Oblique and sigmoidal progradational reflections assigned to the upper Peace River Formation probably crop out at the floor of the river in the Ortona area between the western side of Lake Hicpochee and La Belle. These reflections image a regional-scale progradational deltaic depositional system containing quartz sands with low to moderate estimated hydraulic conductivities. In an approximate 6-mile length of the river between La Belle and Franklin Lock, deeper karstic collapse structures are postulated. These structures influence the geometries of parallel reflections that intersect the river channel. Here, reflections assigned to the Buckingham Limestone Member of the Tamiami Formation (a confining unit) and reflections assigned to the clastic zone of the sandstone aquifer likely crop out at the river bottom. Beneath these shallow reflections, relatively higher amplitude parallel reflections of the carbonate zone of the sandstone aquifer are well displayed in the seismic-reflection profiles. In San Carlos Bay, oblique progradational reflections assigned to the upper Peace River Formation are shown beneath the bay. Almost everywhere beneath the river, a diffuse ground-water flow system is in contact with the channel bottom. Ground-penetrating radar profiles of an area about 2 miles north of the depositional axis of the deltaic depositional system in the Ortona area show that progradational clinoforms imaged on seismic reflection profiles in the Caloosahatchee River are present within about 17 feet of the ground surface. Ground-penetrating radar profiles show southward dipping, oblique progradational reflections assigned to the upper Peace River Formation that are terminated at their tops by a toplapping or erosional discontinuity. These clinoformal reflections image clean quartz sand that is probably characterized by moderate hydraulic conductivity. This sand could be mapped using ground-penetrating radar methods.

Water-Resources Investigations Report↗
USGS2002

Evaluation of trends in pH in the Yampa River, northwestern Colorado, 1950-2000

In 1999, the U.S. Geological Survey began a study of pH trends in the Yampa River from near its headwaters to its mouth. The study was prompted by an apparent historical increase in measured pH at the Yampa River near Maybell, from an average of about 7.6 in the 1950's and 1960's to about 8.3 in the 1980's and 1990's. If real, further increase could cause more frequent exceedances of the Colorado water-quality standard of 9.0 and adversely affect aquatic life in the Yampa River Basin, including Dinosaur National Monument. The principal conclusion of this study is that this apparent historical increase in measured pH was caused mostly by changes in measurement protocol. Synoptic sampling during August 16-19, 1999, a period of relatively warm weather and base flow, showed that late afternoon pH of the Yampa River ranged from 8.46 to 9.20. The largest pH (9.20) exceeded the Colorado water-quality standard and was measured at Yampa River above Elk River, about 1.8 miles downstream from the Steamboat Springs Regional Waste Water Treatment Plant outfall, where nutrient enrichment caused photosynthesis by algae to dominate. Here, the dissolved oxygen concentration was 161 percent of saturation and carbon dioxide (CO2 was at 26 percent of saturation. At Yampa River downstream from a diversion near Hayden, 16.3 miles downstream, the effects of photosynthesis were still dominant, though attenuated by reaeration and dilution with freshwater from the Elk River. About 37.2 miles farther downstream, at Yampa River below Craig, which is about 6.2 miles downstream from the Craig Waste Water Treatment Plant, the effects of photosynthesis increased slightly, and pH rose to 8.80. Respiration plus oxidation of organic matter became dominant at Yampa River at Deerlodge Park in Dinosaur National Monument, where pH was 8.51, dissolved oxygen concentration was at 109 percent of saturation, and CO2 was at 189 percent of saturation. Respiration plus oxidation of organic matter, though diminished, apparently extended to the mouth of the Yampa River. Diurnal measurements on the Yampa River during August 23-26, 1999, show that the effects of photosynthesis and respiration plus oxidation of organic matter decreased downstream with distance from the developed urban area in the eastern part of the basin. Larger night-time values of pH in Dinosaur National Monument at Deerlodge Park and at the mouth of the Yampa River indicate that source waters varied with respect to capacity for respiration plus oxidation and photo-synthesis, that photosynthesis was minor, and that pH was largely controlled by respiration plus oxidation of organic matter. Synoptic sampling was repeated during March 13-16, 2000, when discharge was larger in response to late-winter melting of snow and ice at lower altitudes in the basin. Concentrations of nitrite plus nitrate were about 9 times greater in the Yampa River during March 2000 than during August 1999, and the largest increase (greater than 1,200 percent) was at Yampa River below Craig. At and downstream from Steamboat Springs, Colorado, pH at Yampa River sites averaged 8.85 during synoptic sampling in March 2000 compared to 8.70 in August 1999, with the partial pressure of carbon dioxide gas (PCO2) averaging 67 percent of saturation (compared to 99 percent during August 1999). The apparently larger effects of photosynthesis on pH and dissolved oxygen concentrations during March 2000 compared to August 1999 probably were caused by (1) slower rates of exchange of CO2 into and dissolved oxygen out of the river because of colder and deeper water and (2) slower rates of CO2 production and oxygen consumption resulting from slower rates of respiration by organisms and from slower rates of aerobic decomposition of organic matter in the colder river water and streambed sediment. Hypothetical thermodynamic simulations were done for samples collected in the lower Yampa River Basin to simulate the same amount of photosynthesis th

Water-Resources Investigations Report↗
USGS2002

Water-quality and aquatic-community characteristics of selected reaches of the St. Croix River, Minnesota and Wisconsin, 2000

Synoptic sampling was used to determine chemical and biological characteristics of the St. Croix River within a study reach that extended from near Danbury, Wisconsin to the confluence with the Mississippi River at Prescott, Wisconsin. The study was conducted August 7- September 25, 2000 during summer low flow. Dissolved-residue concentrations were found to increase gradually as the river flows downstream, with an abrupt increase downstream of the confluence with the Sunrise River that was primarily attributed to an increase in calcium and magnesium. Dissolved residue concentrations were further augmented by increased yields of chloride and sulfate in the part of the St. Croix Basin between Nevers Dam near St. Croix Falls, Wisconsin and Marine on St. Croix, Minnesota. Nearly all of the nitrogen in transport was in the form of nitrate and organic nitrogen. Organic nitrogen, mainly in particulate form, accounted for most of the gain in total nitrogen load within the study reach. Nitrogen loading to the mainstem indicated relatively uniform nitrogen inputs from the Clam River, Kettle River, and Snake River watersheds. The rate of nitrogen load accrual increased downstream of the confluence with the Sunrise River and in the subreach extending from Nevers Dam through St. Croix Falls to Franconia, Minnesota. Nitrogen load also increased, primarily because of nitrate input, in the part of Lake St. Croix downstream of the confluence with the Kinnickinnic River. Total phosphorus concentrations and loads reflected variations in the amount of particulate phosphorus in transport. Phosphorus loading increased in the part of the St. Croix River that includes Danbury and the confluences of the Yellow River and Clam River. Phosphorus loading also increased downstream of the confluence with the Sunrise River, but the greatest load increase occurred between Nevers Dam and Franconia. Phosphorus load decreased substantially as the river flowed through the pooled reach of Lake St. Croix downstream of Stillwater. Suspended-sediment concentrations were low, ranging from 4.0 to 36 milligrams per liter. The small amount of sediment in transport was reflected in turbidity measurements that ranged from 0.5 to 3.6 Nephelometry Turbidity Units, and transparency tube measurements that were greater than 60 centimeters at all sites. Biological measures of resource quality change in the St. Croix River along its course from Danbury to Prescott. Changes in the biological indicators of resource quality (fish and invertebrate community composition) are most notable just upstream and downstream of the dam at St. Croix Falls, Wisconsin. Aquatic communities in the upper St. Croix River, from near Danbury to near Rush City, Minnesota, indicate minimal physical and chemical disturbance as evidenced by relatively high taxa richness and greater proportions of taxa intolerant to physical and chemical disturbance. In contrast, aquatic communities downstream of the Sunrise River to Marine on St. Croix indicate both physical and chemical disturbance. Resource monitoring, consisting of short-term diagnostic studies, may be needed in parts of the St. Croix River mainstem and tributaries where results from this study indicate constituent loading is greatest and where the aquatic community composition indicates disturbance. Longer-term trend monitoring may be needed to detect physical, chemical and biological responses to natural processes and human activities in the St. Croix River Basin.

Minnesota, Wisconsin↗
USGS2003

Water-quality assessment of part of the Upper Mississippi River Basin Study Unit, Minnesota and Wisconsin — Nutrients, chlorophyll a, phytoplankton, and suspended sediment in streams, 1996-98

Stream water-quality data from part of the Upper Mississippi River Basin Study Unit (Study Unit) from 1995 through 1998 was used to describe the distribution of nutrients, chlorophyll a, phytoplankton, and suspended sediment; and the influence of natural and anthropogenic factors on reported concentrations, loads, and yields. During the study period, streamflows generally were near to greater than average. Agricultural land cover, particularly on tile-drained soils, had the most substantial influence on nutrients, chlorophyll a , and suspended sediment in the Study Unit. The greatest concentrations and yields of total nitrogen, dissolved nitrite plus nitrate nitrogen, dissolved nitrite nitrogen, total organic plus ammonia nitrogen, total phosphorus, and suspended sediment were measured in a stream representing agricultural land cover on tile-drained soils. Total nitrogen yields also were about 6 times greater in a stream representing agricultural land cover on tile-drained soils than in a stream representing agricultural land cover on naturally welldrained soils. Urban-residential land cover also influenced nutrients and suspended sediment in streams in the Study Unit. Concentrations and yields of total nitrogen, dissolved nitrite plus nitrate nitrogen, total organic plus ammonia nitrogen, total phosphorus, dissolved orthophosphate phosphorus (orthophosphate), and suspended sediment in streams representing urban-residential land cover were less than those representing agricultural land cover on tile drained soil, and greater than those on forested land cover. Nutrients and suspended sediment in the Mississippi, Minnesota, and St. Croix Rivers generally reflect the influence of primary land cover in drainage areas of streams tributary to these rivers. In the Mississippi River, total nitrogen, dissolved nitrite plus nitrate nitrogen, dissolved ammonia nitrogen, total phosphorus, dissolved orthophosphate, and suspended-sediment concentrations and loads increased substantially downstream of the confluence with the Minnesota River at Hastings, Minnesota. Greater concentrations and loads of dissolved orthophosphate in the Mississippi River at Hastings, Minnesota probably were caused by wastewater discharges from the Twin Cities Metropolitan Area (TCMA) and contributions from the Minnesota River. The median dissolved ammonia nitrogen concentration at the Mississippi River at Hastings, Minnesota, based on data collected during this study, was about one-half of the median concentrations previously reported for 1984-93, which can be attributed to reduced ammonia concentrations in municipal wastewater discharged from the TCMA. In the St. Croix River, total nitrogen, dissolved nitrite plus nitrate nitrogen, and total organic plus ammonia nitrogen concentrations were significantly greater at St. Croix Falls, Wisconsin compared to near Danbury, Wisconsin. All nutrient and suspended-sediment loads and yields in the St. Croix River increased in the downstream direction from near Danbury to St. Croix Falls, Wisconsin. Most sites had pronounced seasonal variations in dissolved nitrite plus nitrate nitrogen and dissolved ammonia nitrogen concentrations. At most sites, dissolved nitrite plus nitrate nitrogen concentrations were greatest in the winter and spring and least during the summer and fall. In contrast, the greatest dissolved nitrite plus nitrate nitrogen concentrations in the Little Cobb River near Beauford, Minnesota; Minnesota River near Jordan, Minnesota; and Mississippi River at Hastings and Red Wing, Minnesota occurred during the spring and summer. These seasonal variations in dissolved nitrite plus nitrate nitrogen concentrations may be the result of nitrogen cycling in the soils, as well as crop uptake and hydrologic conditions. The greatest concentrations of dissolved ammonia nitrogen at all sites occurred in the winter and spring. The maximum contaminant level for nitrate of 10 milligrams per liter (mg/L) as nitrogen set by the U.S. Environmental Protection Agency (USEPA) for drinking water was exceeded in 20 percent of the samples analyzed from the Little Cobb River near Beauford, Minnesota, and in 11 percent of the samples analyzed from the Minnesota River near Jordan, Minnesota. The greatest chlorophyll- a concentrations and algal abundances generally were measured in the Little Cobb River near Beauford, Minnesota; Minnesota River near Jordan, Minnesota; Mississippi River at Hastings, Minnesota; and the Mississippi River at Red Wing, Minnesota. Greater concentrations and algal abundances at these sites may have been the result of increased nitrogen and phosphorus concentrations. Total phosphorus concentrations at these sites most frequently exceeded the goal of 0.1 mg/L set by the USEPA to prevent eutrophication. Phytoplankton communities at these sites primarily were dominated by blue-green algae during the summer of 1996. In contrast, at most of the other sites, the phytoplankton community was dominated by diatoms.

Iowa, Minnesota, North Dakota, South Dakota, Wisco↗
USGS2003

Hydrogeology and Simulated Effects of Ground-Water Withdrawals in the Big River Area, Rhode Island

The Rhode Island Water Resources Board is considering expanded use of ground-water resources from the Big River area because increasing water demands in Rhode Island may exceed the capacity of current sources. This report describes the hydrology of the area and numerical simulation models that were used to examine effects of ground-water withdrawals during 1964?98 and to describe potential effects of different withdrawal scenarios in the area. The Big River study area covers 35.7 square miles (mi2) and includes three primary surface-water drainage basins?the Mishnock River Basin above Route 3, the Big River Basin, and the Carr River Basin, which is a tributary to the Big River. The principal aquifer (referred to as the surficial aquifer) in the study area, which is defined as the area of stratified deposits with a saturated thickness estimated to be 10 feet or greater, covers an area of 10.9 mi2. On average, an estimated 75 cubic feet per second (ft3/s) of water flows through the study area and about 70 ft3/s flows out of the area as streamflow in either the Big River (about 63 ft3/s) or the Mishnock River (about 7 ft3/s). Numerical simulation models are used to describe the hydrology of the area under simulated predevelopment conditions, conditions during 1964?98, and conditions that might occur in 14 hypothetical ground-water withdrawal scenarios with total ground-water withdrawal rates in the area that range from 2 to 11 million gallons per day. Streamflow depletion caused by these hypothetical ground-water withdrawals is calculated by comparison with simulated flows for the predevelopment conditions, which are identical to simulated conditions during the 1964?98 period but without withdrawals at public-supply wells and wastewater recharge. Interpretation of numerical simulation results indicates that the three basins in the study area are in fact a single ground-water resource. For example, the Carr River Basin above Capwell Mill Pond is naturally losing water to the Mishnock River Basin. Withdrawals in the Carr River Basin can deplete streamflows in the Mishnock River Basin. Withdrawals in the Mishnock River Basin deplete streamflows in the Big River Basin and can intercept water flowing to the Flat River Reservoir North of Hill Farm Road in Coventry, Rhode Island. Withdrawals in the Big River Basin can deplete streamflows in the western unnamed tributary to the Carr River, but do not deplete streamflows in the Mishnock River Basin or in the Carr River upstream of Capwell Mill Pond. Because withdrawals deplete streamflows in the study area, the total amount of ground water that may be withdrawn for public supply depends on the minimum allowable streamflow criterion that is applied for each basin.

Water-Resources Investigations Report↗
USGS1988

Sedimentation and water quality in the West Branch Shade River basin, Ohio, 1983-85

Loss of channel conveyance from deposition of sediment from abandoned surface mines in the West Branch Shade River basin has resulted in frequent flooding. In addition, water quality in the West Branch Shade River and some of its tributaries is typical of streams affected by acid mine drainage. About 938 acres were surfaced mined and abandoned in West Branch Shade River basin. By the end of 1984, about 450 acres were reclaimed. The purpose of this study was to measure the effects of abandoned surface mines and their reclamation on suspended-sediment load, channel cross-section profile, and water quality of West Branch Shade River. Sediment data were collected from June 1983 through September 1985. Daily suspended-sediment samples were collected and continuous streamflow data were recorded at two locations in West Branch Shade River basin and one location in the unmined, East Branch Shade River basin. Water-quality samples were collected three times per year, from June 1983 through July 1986, at four locations in the West Branch Shade River basin and at one location in East Branch Shade River basin and at one location in East Branch Shade River basin. Stream-channel cross sections were surveyed at least twice per year at 10 locations. During the period of study, annual mean suspended-sediment concentration was unchanged for the unmined, East Branch Shade River basin; 0.28 ton per acre-foot of runoff in 1984 and 1985 water years. Annual suspended-sediment concentration, in tons per acre foot, in West Branch Shade River near Harrisonville, from 8.6 in 1984 water year to 0.15 in 1985 water year. In West Branch Shade River near Burlingham, where 48 percent of the abandoned mines were reclaimed by the end of 1984, annual mean suspended-sediment concentration was unchanged (0.5 ton per acre-foot of runoff) in 1984 and 1985 water years and was twice that of the unmined basin. Channel profiles, surveyed at each of the 10 cross sections, indicated scouring at two locations and filling at one location. West Branch Shade River near Harrisonville was scouring, whereas West Branch Shade River near Burlingham was filling. Although the source of sediment in the headwaters had been greatly reduced with reclamation, the sediments previously deposited and stored in the channel of West Branch Shade River most likely will continue to provide a suspended-sediment supply and contribute to channel filling farther downstream. In addition, part of West Branch Shade River basin is still largely unreclaimed and continues as a suspended-sediment source. On the basis of successive cross-section profiles, the down-stream-most cross section surveyed in Kingsbury Creek, a tributary to West Branch Shade River, also appeared to be scouring. The cause of the scouring is unknown, as no reclamation activities have occurred in that part of the basin. The quality of West Shade River was characteristic of streams draining abandoned or improperly reclaimed surface mines in southeastern Ohio. Median alkalinity was less than 25 mg/L (milligrams per liter) as CaCO3 at the three mined sites. Median sulfate concentration was 44 mg/L at the unmined site compared to 128 mg/L at the mined sites. Median manganese concentration was 10 times higher at the mined sites than the unmined sites. Both sulfate and manganese are indicators of the presence of acid mine drainage. The greatest change in water quality during the study period was observed in West Branch Shade River near Harrisonville, above which all abandoned mine lands were reclaimed. The pH at that site increased to neutral by the end of the study. In addition, alkalinity concentration increased, and acidity concentration decreased. As has been observed in previous studies of abandoned surface mines that have been reclaimed, manganese and sulfate concentrations did not change following reclamation. No change in water quality was observed at the two downstream sites during the period of study. However, th

Water-Resources Investigations Report↗
USGS1996

Trend analysis of selected water-quality data associated with salinity-control projects in the Grand Valley, in the lower Gunnison River basin, and at Meeker Dome, western Colorado

To decrease salt loading to the Colorado River from irrigated agriculture, salinity-control projects have been under construction since 1979 by the Bureau of Reclamation and the U.S. Department of Agriculture in the Grand Valley and since 1988 in the lower Gunnison River Basin of western Colorado. In 1980, a salinity-control project was initiated at Meeker Dome, which involved plugging three abandoned oil wells that were discharging saline water to the White River. Trend analysis was used to determine if the salinity-control projects had affected salinity in the Colorado and White Rivers. The mean annual dissolved-solids load in the Colorado River near the Colorado-Utah State line for water years 1970-93 was about 3.32 million tons. About 46 percent of that load was from the Colorado River upstream from the Grand Valley and about 38 percent was from the Gunnison River. About 16 percent of the dissolved-solids load in the Colorado River near the State line was discharged from the Grand Valley, and most of the Grand Valley dissolved-solids load was from irrigation-induced sources. Monotonic trend analysis of dissolved-solids and major-ion data for the Colorado and Gunnison Rivers was used for determining if salinity-control projects had affected salinity (dissolved solids) in the Colorado River. Data collected in water years 1970-93 at gaging stations on the Colorado River-one near Cameo and the other near the Colorado-Utah State line, and at the station on the Gunnison River near Grand Junction-were analyzed for trends. A computerized procedure developed by the U.S. Geological Survey that uses the nonparametric seasonal Kendall test with adjustment for streamflow was used for trend analysis of periodic and monthly data, and linear regression was used for trend analysis of annual data. Three time periods were tested, including periods that were concurrent with work on salinity-control projects. Many of the trends in unadjusted concentration and load data were not statistically significant. There were downward trends in flow-adjusted dissolved-solids and major-ion concentrations and in monthly dissolved-solids loads for all three stations in the 1970's, prior to the salinity-control projects. The two stations on the Colorado River also had significant downward trends in flow-adjusted concentrations and loads for water years 1986-93. The cumulative effects of salinity-control projects in the Grand Valley and in the lower Gunnison River Basin on salinity in the Colorado River would have become more substantial after the mid-1980's. Part of the decrease in dissolved solids in the Colorado River near the State line probably was related to salinity-control projects; however, there apparently are other factors that are affecting dissolved solids in the upper Colorado River in addition to salinity-control projects. A significant decrease in chloride and sodium concentrations in the White River downstream from Meeker Dome indicated that the well plugging in 1981 was successful in stopping much of the discharge of saline water from the wells. Chloride and sodium concentrations have not changed in the White River at Meeker or downstream from Meeker during water years 1982-95, indicating that the well plugging has remained intact.

Colorado↗
USGS1997

Water-quality assessment of part of the upper Mississippi River Basin, Minnesota and Wisconsin — Nitrogen and phosphorus in streams, streambed sediment, and ground water, 1971-94

Nitrogen and phosphorus in streams, streambed sediment, and ground water were summarized using data from Federal, state, and local agencies as part of an analysis of historical water-quality data for the Upper Mississippi River Basin study unit of the U.S. Geological Survey's National Water-Quality Assessment Program. The Upper Mississippi River Basin study unit encompasses the drainage of the Mississippi River from the source to the outlet of Lake Pepin. This report focuses on a 19,500-square-mile study area in the eastern part of the study unit. The study area included the part of the Upper Mississippi River Basin from Royalton, Minnesota, to the outlet of Lake Pepin, located near Red Wing, Minnesota; the Minnesota River Basin from Jordan, Minnesota, to the confluence with the Mississippi River; and the entire drainage basins of the St. Croix, Cannon, and Vermillion Rivers. The Twin Cities metropolitan area, with a population of approximately 2.3 million people, is located in the south-central part of the study area. Fertilizers and livestock manure were the greatest sources of nitrogen and phosphorus applied to the land surface of the study unit. Approximately 60 percent of the fertilizer was applied to the Minnesota River Basin, which drains agricultural areas in the southern and western parts of the study unit. Concentrations of total nitrite plus nitrate nitrogen, total nitrogen, and total phosphorus in streams, generally were greatest in the tributaries to the Mississippi River draining agricultural areas in the western and southern part of the study area. Concentrations of these constituents generally were least in tributaries draining forested land. The greatest total nitrite plus nitrate nitrogen concentrations generally occurred during the spring and summer in streams draining agricultural areas and in the winter in streams draining forested areas. Total phosphorus concentrations generally were greatest in the spring and summer for all streams. Total nitrite plus nitrate nitrogen, total nitrogen, and total phosphorus concentrations in the Mississippi River increased substantially downstream from the Minnesota River and downstream from wastewater discharges in the Twin Cities metropolitan area. Total ammonia and dissolved orthophosphate concentrations generally were greatest at sites on the Mississippi and Minnesota Rivers downstream from wastewater discharges from the Twin Cities metropolitan area. Total nitrite plus nitrate nitrogen concentrations in streams generally were less than the Maximum Contaminant Level of 10 mg/L (as nitrogen) established by the U.S. Environmental Protection Agency. Total phosphorus concentrations in streams generally were greater than the 0.1 mg/L concentration recommended by the U.S. Environmental Protection Agency at sites located in agricultural areas and on the Mississippi River downstream from its confluence with the Minnesota River. Phosphorus and nitrogen yields were greatest in watersheds primarily draining agricultural land. The majority of the nitrogen and phosphorus loading to the Mississippi River was from the Minnesota River. In the Minnesota River, the nitrogen load primarily was total nitrite plus nitrate nitrogen. Despite increases in fertilizer usage during 1982-91, most stream sites outside of the Twin Cities metropolitan area had no temporal trends in total nitrite plus nitrate nitrogen, total phosphorus, or dissolved orthophosphate concentrations for water years 1984-93. Most sites had a decrease in total ammonia nitrogen concentrations, possibly a result of improvements in wastewater treatment. In the Twin Cities metropolitan area, decreases in total ammonia concentrations in the Mississippi and Minnesota Rivers coincided with increases in total nitrite plus nitrate nitrogen concentrations, probably a result of wastewater treatment plants initiating nitrification processes. Nitrite plus nitrate nitrogen concentrations in ground water reflect land uses and hydrogeologic settings of major aquifers in the study area. Unconfined sand and gravel, buried sand and gravel, and the Prairie du Chien-Jordan were the aquifers most frequently sampled for nitrite plus nitrate nitrogen because they are the principal sources of ground water in the study area. The greatest nitrite plus nitrate nitrogen concentrations reported by Federal and state agencies, some exceeding the U.S. Environmental Protection Agency's Maximum Contaminant level of 10 mg/L by a factor of four, were in water from shallow wells in agricultural and mixed forested and agricultural areas. Water sampled from buried sand and gravel aquifers, which are more shielded from substances leaching from the land surface by layers of clay or till, generally had lower nitrite plus nitrate nitrogen concentrations than water from unconfined sand and gravel aquifers. Nitrite plus nitrate nitrogen concentrations in water samples from the Prairie du Chien-Jordan aquifer were greatest in the Wisconsin part of the study area and in the vicinity of the Cannon River, where the aquifer is commonly unconfined, exposed at land surface, and overlain by agricultural or by mixed forested and agricultural land covers. Dissolved phosphorus concentrations in ground water in the study area generally were near detection limits of 0.01 mg/L or lower, indicating that surface-water eutrophication from phosphorus may be more likely to occur from overland runoff of phosphorus compounds and from direct discharges of treated wastewater than from ground-water base flow. The greatest concentrations of dissolved phosphorus in ground water generally were detected in water samples from wells in urban portions of the study area.

Minnesota, Wisconsin↗
USGS1965

Water resources of the Humboldt River Valley near Winnemucca, Nevada

This report, resulting from studies made by the U.S. Geological Survey as part of the interagency Humboldt River Research Project, describes the qualitative and quantitative relations among the components of the hydrologic system in the Winnemucca Reach of the Humboldt River valley. The area studied includes the segment of the Humboldt River valley between the Comus and Rose Creek gaging stations. It is almost entirely in Humboldt County in north-central Nevada, and is about 200 miles downstream from the headwaters of the Humboldt River. Agriculture is the major economic activity in the area. Inasmuch as the valley lowlands receive an average of about 8 inches of precipitation per year and because the rate of evaporation from free-water surfaces is about six times the average annual precipitation, all crops in the area (largely forage crops) are irrigated. About 85 percent of the cultivated land is irrigated with Humboldt River water; the remainder is irrigated from about 20 irrigation wells. The consolidated rocks of the uplifted fault-block mountains are largely barriers to the movement of ground water and form ground-water and surface-water divides. Unconsolidated deposits of late Tertiary and Quaternary age underlie the valley lowlands to a maximum depth of about 5,000 feet. These deposits are in hydraulic continuity with the Humboldt River and store and transmit most of the economically recoverable ground water. Included in the valley fill is a highly permeable sand and gravel deposit having a maximum thickness of about 90-100 feet; it underlies the flood plain and bordering terraces throughout most of the project area. This deposit is almost completely saturated and contains about 500,000 acre-feet of ground water in storage. The Humboldt River is the source of 90-95 percent of the surface-water inflow to the area. In water years 1949-62 the average annual streamflow at the Comus gaging station at the upstream margin of the area was 172,100 acre-feet; outflow at the Rose Creek gaging station averaged about 155,400 acre-feet. Accordingly, the measured loss of Humboldt River streamflow averaged nearly 17,000 acre-feet per year. Most of this water was transpired by phreatophytes and crops, evaporated from free-water surfaces, and evaporated from bare soil. Inasmuch as practically no tributary streamflow normally discharges into the river in the Winnemucca reach and because pumpage is virtually negligible during the nonirrigation season, gains and losses of streamflow during most of the year reflect the close interrelation of the Humboldt River and the groundwater reservoir. An estimated average of about 14,000 acre-feet per year of ground-water underflow moves toward the Humboldt River from tributary areas. Much of this water discharges into the Humboldt River; hovever, some evaporates or is transpired before reaching the river. More than 65 percent of the average annual flow of the river horn-ally occurs in April, May, and June owing to the spring runoff. The stage of the river generally rises rapidly during these months causing water to move from the river to the ground-water reservoir. Furthermore, the period of high streamflow normally coincides with the irrigation season, and much of the excess irrigation water diverted from the river percolates downward to the zone of saturation. The net measured loss of streamflow in April-June, which averaged about 24,000 acre-feet in water years 1949-62, was about 7,000 acre-feet more than the average annual loss. The estimated net average annual increase of ground water in storage during these months in this period was on the order of 10,000 acre-feet. Following the spring runoff and the irrigation season, normally in July, some of the ground water stored in the flood-plain deposits during the spring runoff begins to discharge into the river. In addition, ground-water inflow from tributary areas again begins to discharge into the river. Experiments utilizin

Water Supply Paper↗
USGS2011

An assessment of stressor extent and biological condition in the North American mid-continent great rivers (USA)

We assessed the North American mid-continent great rivers (Upper Mississippi, Missouri, and Ohio). We estimated the extent of each river in most- (MDC) or least-disturbed condition (LDC) based on multiple biological response indicators: fish and macroinvertebrate, trophic state based on chlorophyll a, macrophyte cover, and exposure of fish-eating wildlife to toxic contaminants in fish tissue (Hg, total chlordane, total DDT, PCBs). We estimated the extent of stressors on each river including nutrients, suspended solids, sediment toxicity, invasive species, and land use (agriculture and impervious surface). All three rivers had a greater percent of their river length in MDC than in LDC based on fish assemblages. The Upper Mississippi River had the greatest percent of river length with eutrophic status. The Ohio River had the greatest percent of river length with fish with tissue contaminant levels toxic to wildlife. Overall, condition indices based on fish assemblages were more sensitive to stress than macroinvertebrate indices. Compared to the streams in its basin, more of the Upper Mississippi and Missouri Rivers were in MDC for nutrients than the Ohio River. Invasive species (Asian carp and Dreissenid mussels) were less widespread and less abundant on the Missouri River than on the other great rivers. The Ohio River had the most urbanized floodplains (greatest percent impervious surface). The Missouri River had the most floodplain agriculture. The effect of large urban areas on river condition was apparent for several indicators. Ecosystem condition based in fish assemblages, trophic state, and fish tissue contamination was related to land use on the floodplain and at the subcatchment scale. This is the first unbiased bioassessment of the mid-continent great rivers in the United States. The indicators, condition thresholds, results, and recommendations from this program are a starting point for improved future great river assessments.

River Systems↗
USGS2006

Environmental contaminants and biomarker responses in fish from the Columbia River and its tributaries: spatial and temporal trends

Fish were collected from 16 sites on rivers in the Columbia River Basin (CRB) from September 1997 to April 1998 to document temporal and spatial trends in the concentrations of accumulative contaminants and to assess contaminant effects on the fish. Sites were located on the mainstem of the Columbia River and on the Snake, Willamette, Yakima, Salmon, and Flathead Rivers. Common carp (Cyprinus carpio), black bass (Micropterus sp.), and largescale sucker (Catostomus macrocheilus) were the targeted species. Fish were field-examined for external and internal lesions, selected organs were weighed to compute somatic indices, and tissue and fluid samples were preserved for fish health and reproductive biomarker analyses. Composite samples of whole fish, grouped by species and gender, from each site were analyzed for organochlorine and elemental contaminants using instrumental methods and for 2,3,7,8-tetrachloro dibenzo-p-dioxin-like activity (TCDD-EQ) using the H4IIE rat hepatoma cell bioassay. Overall, pesticide concentrations were greatest in fish from lower CRB sites and elemental concentrations were greatest in fish from upper CRB sites. These patterns reflected land uses. Lead (Pb) concentrations in fish from the Columbia River at Northport and Grand Coulee, Washington (WA) exceeded fish and wildlife toxicity thresholds (> 0.4 ??g/g). Selenium (Se) concentrations in fish from the Salmon River at Riggins, Idaho (ID), the Columbia River at Vernita Bridge, WA, and the Yakima River at Granger, WA exceeded toxicity thresholds for piscivorous wildlife (> 0.6 ??g/g). Mercury (Hg) concentrations in fish were elevated throughout the basin but were greatest (> 0.4 ??g/g) in predatory fish from the Salmon River at Riggins, ID, the Yakima River at Granger, WA, and the Columbia River at Warrendale, Oregon (OR). Residues of p,p???-DDE were greatest (> 0.8 ??g/g) in fish from agricultural areas of the Snake, Yakima, and Columbia River basins but were not detected in upper CRB fish. Other organochlorine pesticides did not exceed toxicity thresholds in fish or were detected infrequently. Total polychlorinated biphenyls (PCBs; > 0.11 ??g/g) and TCDD-EQs (> 5 pg/g) exceeded wildlife guidelines in fish from the middle and lower CRB, and ethoxyresorufin O-deethylase (EROD) activity was also elevated at many of the same sites. Temporal trend analysis indicated decreasing or stable concentrations of Pb, Se, Hg, p,p???-DDE, and PCBs at most sites where historical data were available. Altered biomarkers were noted in fish throughout the CRB. Fish from some stations had responded to chronic contaminant exposure as indicated by fish health and reproductive biomarker results. Although most fish from some sites had grossly visible external or internal lesions, histopathological analysis determined these to be inflammatory responses associated with helminth or myxosporidian parasites. Many largescale sucker from the Columbia River at Northport and Grand Coulee, WA had external lesions and enlarged spleens, which were likely associated with infections. Intersex male smallmouth bass (Micropterus dolomieu) were found in the Snake River at Lewiston, ID and the Columbia River at Warrendale, OR. Male bass, carp, and largescale sucker containing low concentrations of vitellogenin were common in the CRB, and comparatively high concentrations (> 0.3 mg/mL) were measured in male fish from the Flathead River at Creston, Montana, the Snake River at Ice Harbor Dam, WA, and the Columbia River at Vernita Bridge, WA and Warrendale, OR. Results from our study and other investigations indicate that continued monitoring in the CRB is warranted to identify consistently degraded sites and those with emerging problems. ?? 2005 Elsevier B.V. All rights reserved.

Columbia River Basin↗
USGS2007

Chemical contaminants, health indicators, and reproductive biomarker responses in fish from the Colorado River and its tributaries

Common carp (Cyprinus carpio), black bass (Micropterus spp.), and channel catfish (Ictalurus punctatus) were collected from 14 sites in the Colorado River Basin (CRB) to document spatial trends in accumulative contaminants, health indicators, and reproductive biomarkers. Organochlorine residues, 2,3,7,8-tetrachlorodibenzo-p-dioxin-like activity (TCDD-EQ), and elemental contaminants were measured in composite samples of whole fish, grouped by species and gender, from each site. Selenium (Se) and mercury (Hg) concentrations in fish were elevated throughout the CRB, and pesticide concentrations were greatest in fish from agricultural areas in the Lower Colorado River and Gila River. Selenium concentrations exceeded toxicity thresholds for fish (> 1.0????g/g ww) at all CRB sites except the Gila River at Hayden, Arizona. Mercury concentrations were elevated (> 0.1????g/g ww) in fish from the Yampa River at Lay, Colorado; the Green River at Ouray National Wildlife Refuge (NWR), Utah and San Rafael, Utah; the San Juan River at Hogback Diversion, New Mexico; and the Colorado River at Gold Bar Canyon, Utah, Needles, California, and Imperial Dam, Arizona. Concentrations of p,p???-DDE were relatively high in fish from the Gila River at Arlington, Arizona (> 1.0????g/g ww) and Phoenix, Arizona (> 0.5????g/g ww). Concentrations of other formerly used pesticides including toxaphene, total chlordanes, and dieldrin were also greatest at these two sites but did not exceed toxicity thresholds. Currently used pesticides such as Dacthal, endosulfan, ??-HCH, and methoxychlor were also greatest in fish from the Gila River downstream of Phoenix. Total polychlorinated biphenyls (PCBs; > 0.11????g/g ww) and TCDD-EQs (> 5??pg/g ww) exceeded wildlife guidelines in fish from the Gila River at Phoenix. Hepatic ethoxyresorufin O-deethylase (EROD) activity was also relatively high in carp from the Gila River at Phoenix and in bass from the Green River at Ouray NWR. Fish from some sites showed evidence of contaminant exposure as indicated by fish health indicators and reproductive biomarker results. Multiple health indicators including altered body and organ weights and high health assessment index scores may be associated with elevated Se concentrations in fish from the Colorado River at Loma, Colorado and Needles. Although grossly visible external or internal lesions were found on most fish from some sites, histopathological analysis determined many of these to be inflammatory responses associated with parasites. Edema, exophthalmos, and cataracts were noted in fish from sites with elevated Se concentrations. Intersex fish were found at seven of 14 sites and included smallmouth bass (M. dolomieu), largemouth bass (M. salmoides), catfish, and carp and may indicate exposure to endocrine disrupting compounds. A high proportion of smallmouth bass from the Yampa River at Lay (70%) was intersex but the cause of this condition is unknown. Male carp, bass, and catfish with low concentrations of vitellogenin were common in the CRB. Comparatively high vitellogenin concentrations (> 0.2??mg/mL) were measured in male bass from the Green River at Ouray NWR and the Colorado River at Imperial Dam and indicate exposure to estrogenic or anti-androgenic chemicals. Anomalous reproductive biomarkers including low GSI and gonadal abnormalities (calcifications, edema, and parasites) observed in fish downstream of Phoenix are likely related to the poor water-quality of the Gila River in this area.

Colorado River Basin↗
USGS1999

Occurrence and transport of total mercury and methyl mercury in the Sacramento River Basin, California

Mercury poses a water-quality problem for California's Sacramento River, a large river with a mean annual discharge of over 650 m3/s. This river discharges into the San Francisco Bay, and numerous fish species of the bay and river contain mercury levels high enough to affect human health if consumed. Two possible sources of mercury are the mercury mines in the Coast Ranges and the gold mines in the Sierra Nevada. Mercury was once mined in the Coast Ranges, west of the Sacramento River, and used to process gold in the Sierra Nevada, east of the river. The mineralogy of the Coast Ranges mercury deposits is mainly cinnabar (HgS), but elemental mercury was used to process gold in the Sierra Nevada. Residual mercury from mineral processing in the Sierra Nevada is mainly in elemental form or in association with oxide particles or organic matter and is biologically available. Recent bed-sediment sampling, at sites below large reservoirs, showed elevated levels of total mercury (median concentration 0.28 ??g/g) in every large river (the Feather, Yuba, Bear, and American rivers) draining the Sierra Nevada gold region. Monthly sampling for mercury in unfiltered water shows relatively low concentrations during the nonrainy season in samples collected throughout the Sacramento River Basin, but significantly higher concentrations following storm-water runoff. Measured concentrations, following storm-water runoff, frequently exceeded the state of California standards for the protection of aquatic life. Results from the first year of a 2-year program of sampling for methyl mercury in unfiltered water showed similar median concentrations (0.1 ng/l) at all sampling locations, but with apparent high seasonal concentrations measured during autumn and winter. Methyl mercury concentrations were not significantly higher in rice field runoff water, even though rice production involves the creation of seasonal wetlands: higher rates of methylation are known to occur in stagnant wetland environments that have high dissolved carbon.Mercury poses a water-quality problem for California's Sacramento River, a large river with a mean annual discharge of over 650 m3/s. This river discharges into the San Francisco Bay, and numerous fish species of the bay and river contain mercury levels high enough to affect human health if consumed. Two possible sources of mercury are the mercury mines in the Coast Ranges and the gold mines in the Sierra Nevada. Mercury was once mined in the Coast Ranges, west of the Sacramento River, and used to process gold in the Sierra Nevada east of the river. The mineralogy of the Coast Ranges mercury deposits is mainly cinnabar (HgS), but elemental mercury was used to process gold in the Sierra Nevada. Residual mercury from mineral processing in the Sierra Nevada is mainly in elemental form or in association with oxide particles or organic matter and is biologically available. Recent bed-sediment sampling, at sites below large reservoirs, showed elevated levels of total mercury (median concentration 0.28 ??g/g) in every large river (the Feather, Yuba, Bear, and American rivers) draining the Sierra Nevada gold region. Monthly sampling for mercury in unfiltered water shows relatively low concentrations during the nonrainy season in samples collected throughout the Sacramento River Basin, but significantly higher concentrations following storm-water runoff. Measured concentrations, following storm-water runoff, frequently exceeded the state of California standards for the protection of aquatic life. Results from the first year of a 2-year program of sampling for methyl mercury in unfiltered water showed similar median concentrations (0.1 ng/l) at all sampling locations, but with apparent high seasonal concentrations measured during autumn and winter. Methyl mercury concentrations were not significantly higher in rice field runoff water, even though rice production involves the creation of seasonal wetlands: higher rates of methylation a

Journal of Geochemical Exploration↗
USGS1994

Accounting for consumptive use of Lower Colorado River water in Arizona, California, Nevada, and Utah

In the Colorado River valley between the east end of Lake Mead and the international boundary with Mexico (see figure), the river is the principal source of water for agricultural, domestic, municipal, industrial, hydroelectric-power generation, and recreational purposes. Water is stored in surface reservoirs and in the river aquifer---permeable sediments and sedimentary rocks that fill the lower Colorado River valley and adjacent tributary valleys. The hydraulic connection between the river and the river aquifer, overbank flow prior to building of the dams, and infiltration as the reservoirs filled allowed the sediments and sedimentary rocks to become saturated with water from the river. Ratios of isotopes of hydrogen and oxygen in water from wells indicate that most of the water in the river aquifer beneath the flood plain and in many places beneath the adjacent alluvial slopes originated from the river. The water table in the river aquifer extends from the river, beneath the flood plain, and under the alluvial slopes until it intersects bedrock. Precipitation in the surrounding mountains and inflow from tributary valleys also contribute small quantities of water to the river aquifer. Consumptive use of river water in the valley results from evapotranspiration by vegetation (crops and phreatophytes) on the flood plain, pumpage from wells to meet domestic and municipal needs, and pumpage from the river for export to areas in California, Arizona, and Nevada outside of the river valley. Most crops are grown on the flood plain; in a few areas, land on the adjacent terraces has been cultivated. Crops were grown on about 70 percent of the total vegetated area in 1984. Phreatophytes---natural vegetation that obtains water from the river aquifer---covered the remaining vegetated areas on the uncultivated flood plain. Most of the water used for irrigation is diverted or pumped directly from the river and reservoirs. Most of the water used for domestic and municipal purposes is pumped from wells on the flood plain, on adjacent alluvial slopes, and in tributary valleys. River water also is delivered to Mexico in accordance with an international treaty.

Arizona, California, Nevada, Utah↗
USGS2006

Trends in streamflow of the San Pedro River, southeastern Arizona, and regional trends in precipitation and streamflow in southeastern Arizona and southwestern New Mexico

This study was done to improve the understanding of trends in streamflow of the San Pedro River in southeastern Arizona. Annual streamflow of the river at Charleston, Arizona, has decreased by more than 50 percent during the 20th century. The San Pedro River is one of the few remaining free-flowing perennial streams in the arid Southwestern United States, and the riparian forest along the river supports several endangered species and is an important habitat for migratory birds. Trends in seasonal and annual precipitation and streamflow were evaluated for surrounding areas in southeastern Arizona and southwestern New Mexico to provide a regional perspective for the trends of the San Pedro River. Seasonal and annual streamflow trends and the relation between precipitation and streamflow in the San Pedro River Basin were evaluated to improve the understanding of the causes of trends. There were few significant trends in seasonal and annual precipitation or streamflow for the regional study area. Precipitation and streamflow records were analyzed for 11 time periods ranging from 1930 to 2002; no significant trends were found in 92 percent of the trend tests for precipitation, and no significant trends were found in 79 percent of the trend tests for streamflow. For the trends in precipitation that were significant, 90 percent were positive and most of those positive trends were in records of winter, spring, or annual precipitation that started during the mid-century drought in 1945-60. For the trends in streamflow that were significant, about half were positive and half were negative. Trends in precipitation in the San Pedro River Basin were similar to regional precipitation trends for spring and fall values and were different for summer and annual values. The largest difference was in annual precipitation, for which no trend tests were significant in the San Pedro River Basin, and 23 percent of the trend tests were significantly positive in the rest of the study area. Streamflow trends for the San Pedro River were different from regional streamflow trends. All seasonal flows for the San Pedro River, except winter flows, had significant decreasing trends, and seasonal flows for most streams in the rest of the study area had either no trend or a significant increasing trend. Two streams adjacent to the San Pedro River Basin (Whitewater Draw and Santa Cruz River), however, had significant decreasing trends in summer streamflow. Factors that caused the decreasing trends in streamflow of the San Pedro River at Charleston were investigated. Possible factors were fluctuations in precipitation and air temperature, changes in watershed characteristics, human activities, or changes in seasonal distribution of bank storage. This study statistically removed or accounted for the variation in streamflow caused by fluctuations in precipitation. Thus, the remaining variation or trend in streamflow was caused by factors other than precipitation. Two methods were used to partition the variation in streamflow and to determine trends in the partitioned variation: (1) regression analysis between precipitation and streamflow using all years in the record and evaluation of time trends in regression residuals, and (2) development of regression equations between precipitation and streamflow for three time periods (early, middle, and late parts of the record) and testing to determine if the three regression equations were significantly different. The methods were applied to monthly values of total flow (average flow) and storm runoff (maximum daily mean flow) for 1913-2002, and to monthly values of low flow (3-day low flow) for 1931-2002. Statistical tests provide strong evidence that factors other than precipitation caused a decrease in streamflow of the San Pedro River. Factors other than precipitation caused significant decreasing trends in streamflows for late spring through early winter and did not cause significant trends for late winter through early spring. Total flows had significant decreasing trends in June through December, low flows had significant decreasing trends in May through December, and storm runoff had significant decreasing trends in July through September. The effects of factors other than precipitation were tested only for July through October for storm runoff. Besides fluctuations in precipitation, the principal factors that could have caused decreasing streamflow trends are (1) changes in watershed characteristics such as changes in riparian vegetation, changes in upland vegetation, and changes in stream-channel morphology, and (2) human activities such as ground-water pumping, construction of runoff-detention structures, urbanization, and cattle ranching (grazing). Changes in upland and riparian vegetation likely were major factors in the decreasing trends in total streamflows and low flows. Total flows and low flows in summer and fall were significantly affected by factors other than precipitation, but late winter flows were not significantly affected. The significant effects coincide with high rates of transpiration from vegetation in the summer and the nonsignificant effects coincide with low rates of transpiration in the late winter. Another piece of evidence that implicates vegetation as a cause is that the upland and riparian vegetation of the San Pedro River Basin changed during the 20th century. The relative proportions of different species changed in upland vegetation (woody plants increased and grasses decreased), and the areal extent and density of riparian vegetation increased substantially. Ground-water pumping in the United States and Mexico had a mixed influence on streamflow trends at Charleston, Arizona; statistical analyses indicate that seasonal pumping from wells near the river for irrigation in the spring and summer was a major factor in the decrease in low flows and that year-round pumping from wells in the regional aquifer away from the river was not a major factor in the decrease in low flows. If regional pumping had caused a trend, the pumping should have affected low flows for all months of the year, but factors other than precipitation did not cause significant trends in low flows for January, February, March, and May. Most of the local pumping near the river was during the spring and summer, and this seasonal pumping probably caused some decreases in summer low flows. These conclusions are for trends from 1913 to 2002, and regional pumping in the United States and Mexico could affect streamflow at Charleston in the future, because regional ground-water pumping often has a delayed effect on streamflows.

Arizona, New Mexico↗