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Streamflow characteristics for the Black Hills of South Dakota, through water year 1993

This report summarizes streamflow records and describes streamflow characteristics for streams draining the Black Hills of western South Dakota. Monthly and annual streamflow records are tabulated for all available years of record, through water year 1993, for 129 continuous-record gaging stations, including 111 stations for which records of daily flow are available and 18 stations for which only monthly records are available. Various summary statistics and graphics are presented for stations with sufficient periods of record. In addition to streamflow summaries, records of monthend contents are presented for five reservoirs operated by the Bureau of Reclamation in the Black Hills area. Streamflow characteristics are described for four categories of hydrogeologic settings, including interior sedimentary basins, interior crystalline basins, interior basins downstream of loss zones (loss-zone basins), and exterior basins. All of the interior basins are located predominantly within the outermost extent of the outcrop of the Inyan Kara Group and the exterior basins are located predominantly beyond this outcrop. Distinct differences in variability of annual and monthly streamflow are described for the four categories of hydrogeologic settings. The interior sedimentary basins, which are dominated by springflow from headwater areas, have the smallest variability in both annual and monthly flow, as a group. The exterior basins, as a group, have the largest variability in both annual and monthly flow. Streamflow variability for the interior crystalline basins, which are composed primarily of Precambrian and Tertiary igneous and metamorphic rocks, generally falls midway between the interior sedimentary and exterior basins. Loss-zone stations, which are located downstream of loss zones that occur where streams cross outcrops of the Madison Limestone and other overlying sedimentary units, exhibit the widest range in streamflow variability of any of the categories. Most of the loss-zone basins have springs located upstream of the gaging stations, but downstream of the loss zones. Flow at several of the loss-zone stations is dominated by large and consistent springflow; however, flow at other loss-zone stations is dominated by streamflow losses or by tributary inflows between the loss zones and the gaging stations, which results in extremely variable streamflow characteristics. It is demonstrated that springflow in Battle, Spring, Elk, and Bear Butte Creeks is much more variable than in Cascade Springs, Fall River, Beaver Creek, and Redwater River. Interior crystalline basins and exterior basins are shown to be much more responsive to climatic conditions than the springflow-dominated basins. Zero-flow months have been recorded for all of the exterior basins and most of the interior crystalline basins; however, zero-flow months have not been recorded for any of the interior sedimentary basins. Zero-flow months have not been recorded for the loss-zone stations with large, consistent springflow; however, zero-flow months are common for loss-zone stations with smaller, less consistent springs. Direct surface runoff is demonstrated to be uncommon for outcrops of the Madison Limestone and Minnelusa Formation. Examination of streamflow records for two basins with large outcrops of these formations indicates that direct surface runoff seldom occurs. Annual streamflow is shown to increase from south to north, which is consistent with climatic patterns for the area. Annual yield generally is larger for all of the interior categories than for the exterior basins; however, this is consistent with larger precipitation and smaller evapotranspiration rates at higher elevations. Annual yields generally are largest for the interior sedimentary basins; however, all of these basins are located in the northern Black Hills. Interior crystalline basins located in the northern Black Hills have annual yields that are comparable with interior sedimentary basins.

South Dakota↗

Water-quality assessment of part of the Upper Mississippi River Basin, Minnesota and Wisconsin - Ground-water quality in three different land-use areas, 1996-98

The surficial sand and gravel aquifer is susceptible to effects from land-use in the Upper Mississippi River Basin study unit of the National Water-Quality Assessment (NAWQA) Program. The purpose of this report is to describe the ground-water quality and the assessment of how different land-uses affect the shallow ground-water quality in the surficial sand and gravel aquifer. Ground-water quality was compared in three different land-use areas; an urban residential/commercial area on the edge of the Anoka Sand Plain in a portion of the Twin Cities metropolitan area (urban study), an intensive agricultural area in the Anoka Sand Plain (agricultural study), and a forested area in the Bemidji-Bagley Sand Plain (forested study). Ground water was sampled and analyzed for about 200 constituents, including physical parameters, major ions, selected trace elements, nutrients, dissolved organic carbon, selected pesticides, selected volatile organic compounds (VOCs), and tritium. The urban study wells were sampled during June and July 1996. The agricultural study wells were sampled during May and September 1998. The forested study wells were sampled during June 1998. The depth to water below the land surface generally was less than 20 ft in all three land-use studies. The median pH value in the urban study was 7.2, with medians in the agricultural and forested studies at 7.4 and 7.5, respectively. The median specific conductance was significantly greater in the urban study than in the agricultural and forested studies (914, 553, and 487 µS/cm respectively). The median dissolved oxygen concentration in the urban study (0.9 mg/L) was significantly less than the median in the agricultural or forested studies (5.3 and 2.3 mg/L respectively). Alkalinities in the agricultural study, with a median of 178 mg/L as CaCO 3 , were significantly less than medians in the urban or forested studies (261 and 246 mg/L as CaCO 3 , respectively). The water composition in the surficial aquifer in all three land-use studies is dominated by calcium, magnesium, and bicarbonate. Sulfate and chloride concentrations in water samples were significantly greater in the urban study than in the agricultural or forested studies, and concentrations in the forested study were least. Most of the water samples in all three land-use studies were very hard (greater than 180 mg/L as CaCO 3 ). Nitrate-nitrogen concentrations were greatest in the agricultural study, in which 38 percent of water samples exceeded the U.S. Environmental Protection Agency’s maximum contaminant level (MCL) for nitrate-nitrogen. Nitrate-nitrogen was greater than the MCL in 3 percent of urban study samples. None of the forested study samples exceeded the MCL for nitrate-nitrogen. Concentrations of phosphorus generally were less than 0.05 mg/ L, with no significant differences between the land-uses. A total of 19 pesticides were detected in water samples from one or more land-use study wells, with 11 pesticides detected in the urban study, 14 detected in the agricultural study, and 4 detected in the forested study. Atrazine, deethylatrazine, and simazine were the only pesticides detected in all three land-use studies. A significantly greater percentage of pesticide detections were present in water samples from the agricultural study than from the urban or forested studies (86.2, 56.7, and 46.7 percent, respectively). Prometon was the most frequently detected pesticide in the urban study. Atrazine and deethylatrazine were the most frequently detected pesticides in the agricultural and forested studies. Twenty-one VOCs were detected in water samples from one or more land-use study wells, with 19 detected in the urban study, 7 detected in the agricultural study, and none detected in the forested study. Chloromethane, trichloromethane, methylbenzene, trichlorofluoromethane, and benzene were all detected in both the urban and agricultural studies. A significantly greater percentage of VOC detections were present in water samples from the urban study than from the agricultural study (90 and 50 percent, respectively). Carbon disulfide was the most frequently detected VOC in the urban study. The compound 1,2,3,4-tetramethyl benzene was the most frequently detected VOC in the agricultural study. Tritium concentrations indicate that the water in the surficial sand and gravel aquifer has been recharged since 1953. Median tritium concentrations ranged from 11.6 to 12.8 tritium units. No significant difference in tritium concentrations was present between the three land-use studies. Comparisons of previous land-use studies in Minnesota with the three NAWQA land-use studies generally indicated the same patterns. Ground-water quality in surficial sand and gravel aquifers is affected by land-use practices. Ground water in urban studies has greater specific conductances, alkalinities, chloride, sodium, sulfate, and dissolved solid concentrations than agricultural or forested/undeveloped studies. Nitrate-nitrogen was detected in greater concentrations in agricultural studies than in urban studies, with concentrations in the forested/undeveloped studies less than in the agricultural or the urban studies. Agricultural studies have the greatest detection rates, numbers, and total concentrations of pesticides. Pesticide detection rates and total pesticide concentrations in the urban studies were less than in the agricultural studies, with the most frequently detected pesticides (prometon and dicamba) different than those in the agricultural studies (atrazine and deethylatrazine). A greater number of VOCs were detected in urban studies and at greater concentrations than in agricultural studies. Few pesticides or VOCs were detected in forested/undeveloped studies.

Minnesota↗

Methods for estimating low-flow statistics for Massachusetts streams

Methods and computer software are described in this report for determining flow duration, low-flow frequency statistics, and August median flows. These low-flow statistics can be estimated for unregulated streams in Massachusetts using different methods depending on whether the location of interest is at a streamgaging station, a low-flow partial-record station, or an ungaged site where no data are available. Low-flow statistics for streamgaging stations can be estimated using standard U.S. Geological Survey methods described in the report. The MOVE.1 mathematical method and a graphical correlation method can be used to estimate low-flow statistics for low-flow partial-record stations. The MOVE.1 method is recommended when the relation between measured flows at a partial-record station and daily mean flows at a nearby, hydrologically similar streamgaging station is linear, and the graphical method is recommended when the relation is curved. Equations are presented for computing the variance and equivalent years of record for estimates of low-flow statistics for low-flow partial-record stations when either a single or multiple index stations are used to determine the estimates. The drainage-area ratio method or regression equations can be used to estimate low-flow statistics for ungaged sites where no data are available. The drainage-area ratio method is generally as accurate as or more accurate than regression estimates when the drainage-area ratio for an ungaged site is between 0.3 and 1.5 times the drainage area of the index data-collection site. Regression equations were developed to estimate the natural, long-term 99-, 98-, 95-, 90-, 85-, 80-, 75-, 70-, 60-, and 50-percent duration flows; the 7-day, 2-year and the 7-day, 10-year low flows; and the August median flow for ungaged sites in Massachusetts. Streamflow statistics and basin characteristics for 87 to 133 streamgaging stations and low-flow partial-record stations were used to develop the equations. The streamgaging stations had from 2 to 81 years of record, with a mean record length of 37 years. The low-flow partial-record stations had from 8 to 36 streamflow measurements, with a median of 14 measurements. All basin characteristics were determined from digital map data. The basin characteristics that were statistically significant in most of the final regression equations were drainage area, the area of stratified-drift deposits per unit of stream length plus 0.1, mean basin slope, and an indicator variable that was 0 in the eastern region and 1 in the western region of Massachusetts. The equations were developed by use of weighted-least-squares regression analyses, with weights assigned proportional to the years of record and inversely proportional to the variances of the streamflow statistics for the stations. Standard errors of prediction ranged from 70.7 to 17.5 percent for the equations to predict the 7-day, 10-year low flow and 50-percent duration flow, respectively. The equations are not applicable for use in the Southeast Coastal region of the State, or where basin characteristics for the selected ungaged site are outside the ranges of those for the stations used in the regression analyses. A World Wide Web application was developed that provides streamflow statistics for data collection stations from a data base and for ungaged sites by measuring the necessary basin characteristics for the site and solving the regression equations. Output provided by the Web application for ungaged sites includes a map of the drainage-basin boundary determined for the site, the measured basin characteristics, the estimated streamflow statistics, and 90-percent prediction intervals for the estimates. An equation is provided for combining regression and correlation estimates to obtain improved estimates of the streamflow statistics for low-flow partial-record stations. An equation is also provided for combining regression and drainage-area ratio estimates to obtain improved e

Massachusetts↗

Water-quality assessment of the Rio Grande Valley study unit, Colorado, New Mexico, and Texas -- Analysis of selected nutrient, suspended-sediment, and pesticide data

This report contains a summary of data compiled from sources throughout the Rio Grande Valley study unit of the National Water-Quality Assessment program. Information presented includes the sources and types of water-quality data available, the utility of water-quality data for statistical analysis, and a description of recent water-quality conditions and trends and their relation to natural and human factors. Water-quality data are limited to concentrations of selected nutrient species in surface water and ground water, concentrations of suspended sediment and suspended solids in surface water, and pesticides in surface water, ground water, and biota. The Rio Grande Valley study unit includes about 45,900 square miles in Colorado, New Mexico, and Texas upstream from the streamflow-monitoring station Rio Grande at El Paso, Texas. The area also includes the San Luis Closed Basin and the surface-water closed basins east of the Continental Divide and north of the United States-Mexico international border. The Rio Grande drains about 29,300 square miles in these States; the remainder of the study unit area is in closed basins. Concentrations of all nutrients found in surface-water samples collected from the Rio Grande, with the exception of phosphorus, generally remained nearly constant from the northernmost station in the study unit to Rio Grande near Isleta, where concentrations were larger by an order of magnitude. Total nitrogen and total phosphorus loads increased downstream between Lobatos, Colorado, and Albuquerque, New Mexico. Nutrient concentrations remained elevated with slight variations until downstream from Elephant Butte Reservoir, where nutrient concentrations were lower. Nutrient concentrations then increased downstream from the reservoir, as evidenced by elevated concentrations at Rio Grande at El Paso, Texas. Suspended-sediment concentrations were similar at stations upstream from Otowi Bridge near San Ildefonso, New Mexico. The concentration and estimated load were nearly two orders of magnitude larger at this station relative to upstream stations. Cochiti Lake allows suspended sediment to settle, thus the resulting concentration is substantially lower downstream from the reservoir. Downstream from Cochiti Lake, concentrations again increased due to inflow from tributaries, other ephemeral streams and arroyos, and agricultural and urban areas. Two ephemeral tributaries (Rio Puerco and Rio Salado, which are south of Albuquerque) contribute substantial amounts of suspended sediment to the Rio Grande. Suspended-sediment concentrations in the Rio Grande just downstream from Elephant Butte Dam decreased by nearly three orders of magnitude due to settling in the reservoir. Concentrations then increased due to agricultural and urban impacts downstream from the reservoir. Nutrients in ground water in the study unit do not appear to be a widespread problem. However, localized areas that have elevated nitrate concentrations have been documented. The largest median nitrate concentration was found in water from wells located in the Basin and Range-mountains-urban data stratum (3.0 milligrams per liter) and the smallest median nitrate concentration was found in water from wells located in the Southern Rocky Mountainsmountains-forest data stratum (0.08 milligram per liter). Few (3 percent) nitrate concentrations in water from wells in all data strata were greater than 10 milligrams per liter, and most (82 percent) were less than 2 milligrams per liter. Comparison of nitrate concentrations in water from wells located in specific land-use settings across all hydrogeologic settings, with the exception of the Colorado Plateau, indicated that the largest median nitrate concentration was associated with rangeland land use and that larger nitrate concentrations were found in water from shallow wells. Water from wells located in areas of rangeland land use consistently had larger median nutrient concentrations than water from wells in areas of other land uses. The largest median ammonia concentration was in water from wells located in the Colorado Plateau-San Juan Basin-rangeland data stratum (0.27 milligram per liter). Most median ammonia concentrations were less than 0.03 milligram per liter, indicating that elevated ammonia concentrations are not a major issue in the study unit. The largest median orthophosphate concentration was found in water from wells located in the Southern Rocky Mountains-mountains-forest data stratum (0.15 milligram per liter) and the smallest was found in water from wells located in the Basin and Range-mountains-urban data stratum (0.02 milligram per liter). Most orthophosphate concentrations (85 percent) sampled were less than 0.2 milligram per liter, indicating that elevated orthophosphate concentrations are not a major issue in the study unit. Pesticide analyses were available for only 38 ground-water sampling sites in the Rio Grande Valley study unit. Diazinon, at a concentration of 0.01 microgram per liter, was the only pesticide detected and it was detected at only one site. More study is needed to determine if pesticides are affecting ground-water quality in the Rio Grande Valley study unit. Surface-water biological pesticide data were inadequate for in-depth analysis. The primary sources of data were the U.S. Fish and Wildlife Service and the U.S. Geological Survey. In the U.S. Fish and Wildlife Service study p,p'-DDE, a degradation product of DDT, was detected most frequently; highest concentrations were found at Stahman Farms in carp (6.3 micrograms per gram wet-weight) and at Hatch in Western kingbird (5.1 micrograms per gram wet-weight). In the U.S. Geological Survey study of Bosque del Apache National Wildlife Refuge no detectable organochlorine concentrations were found in plants, but detectable levels of p,p'-DDE were found in coot and carp, with a maximum concentration of 0.12 microgram per gram wet-weight found in coot.

Colorado, New Mexico, Texas↗

Scour assessments and sediment-transport simulation for selected bridge sites in South Dakota

Scour at bridges is a major concern in the design of new bridges and in the evaluation of structural stability of existing bridges. Equations for estimating pier, contraction, and abutment scour have been developed from numerous laboratory studies using sand-bed flumes, but little verification of these scour equations has been done for actual rivers with various bed conditions. This report describes the results of reconnaissance and detailed scour assessments and a sediment-transport simulation for selected bridge sites in South Dakota. Reconnaissance scour assessments were done during 1991 for 32 bridge sites. The reconnaissance assessments for each bridge site included compilation of general and structural data, field inspection to record and measure pertinent scour variables, and evaluation of scour susceptibility using various scour-index forms. Observed pier scour at the 32 sites ranged from 0 to 7 feet, observed contraction scour ranged from 0 to 4 feet, and observed abutment scour ranged from 0 to 10 feet. Thirteen bridge sites having high potential for scour were selected for detailed assessments, which were accomplished during 1992-95. These detailed assessments included prediction of scour depths for 2-, 100-, and 500-year flows using selected published scour equations; measurement of scour during high flows; comparison of measured and predicted scour; and identification of which scour equations best predict actual scour. The medians of predicted pier-scour depth at each of the 13 bridge sites (using 13 scour equations) ranged from 2.4 to 6.8 feet for the 2-year flows and ranged from 3.4 to 13.3 feet for the 500-year flows. The maximum pier scour measured during high flows ranged from 0 to 8.5 feet. Statistical comparison (Spearman rank correlation) of predicted pier-scour depths (using flow data col- lected during scour measurements) indicate that the Laursen, Shen (method b), Colorado State University, and Blench (method b) equations correlate closer with measured scour than do the other prediction equations. The predicted pier-scour depths using the Varzeliotis and Carstens equations have weak statistical rela- tions with measured scour depths. Medians of predicted pier-scour depth from the Shen (method a), Chitale, Bata, and Carstens equations are statistically equal to the median of measured pier-scour depths, based on the Wilcoxon signed-ranks test. The medians of contraction scour depth at each of the 13 bridge sites (using one equation) ranged from -0.1 foot for the 2- year flows to 23.2 feet for the 500-year flows. The maximum contraction scour measured during high flows ranged from 0 to 3.0 feet. The contraction- scour prediction equation substantially overestimated the scour depths in almost all comparisons with the measured scour depths. A significant reason for this discrepancy is due to the wide flood plain (as wide as 5,000 feet) at most of the bridge sites that were investigated. One possible way to reduce this effect for bridge design is to make a decision on what is the effective approach section and thereby limit the size of the bridge flow approach width. The medians of abutment-scour depth at each of the 13 bridge sites (using five equations) ranged from 8.2 to 16.5 feet for the 2-year flows and ranged from 5.7 to 41 feet for the 500-year flows. The maximum abutment scour measured during high flows ranged from 0 to 4.0 feet. The abutment-scour prediction equations also substantially overestimated the scour depths in almost all comparisons with the measured scour depths. The Liu and others (live bed) equation predicted abutment-scour depths substantially lower than the other four abutment-scour equations and closer to the actual measured scour depths. However, this equation at times predicted greater scour depths for 2-year flows than it did for 500-year flows, making its use highly questionable. Again, limiting the bridge flow approach width would produce more reasonable predicted abutment scour.

Water-Resources Investigations Report↗

Stream Bank Stability in Eastern Nebraska

Dredged and straightened channels in eastern Nebraska have experienced degradation leading to channel widening by bank failure. Degradation has progressed headward and affected the drainage systems upstream from the modified reaches. This report describes a study that was undertaken to analyze bank stability at selected sites in eastern Nebraska and develop a simplified method for estimating the stability of banks at future study sites. Bank cross sections along straight reaches of channel and geotechnical data were collected at approximately 150 sites in 26 counties of eastern Nebraska. The sites were categorized into three groups based on mapped soil permeability. With increasing permeability of the soil groups, the median cohesion values decreased and the median friction angles increased. Three analytical methods were used to determine if banks were stable (should not fail even when saturated), at risk (should not fail unless saturated), or unstable (should have already failed). The Culmann and Agricultural Research Service methods were based on the Coulomb equation and planar failure; an indirect method was developed that was based on Bishop's simplified method of slices and rotational failure. The maximum angle from horizontal at which the bank would be stable for the given soil and bank height conditions also was computed with the indirect method. Because of few soil shear-strength data, all analyses were based on the assumption of homogeneous banks, which was later shown to be atypical, at least for some banks. Using the Culmann method and assuming no soil tension cracks, 67 percent of all 908 bank sections were identified as stable, 32 percent were at risk, and 1 percent were unstable; when tension cracks were assumed, the results changed to 58 percent stable, 40 percent at risk, and 1 percent unstable. Using the Agricultural Research Service method, 67 percent of all bank sections were identified as stable and 33 percent were at risk. Using the indirect method, 62 percent of all bank sections were identified as stable and 31 percent were at risk; 3 percent were unstable, and 3 percent were outside of the range of the tables developed for the method. For each of the methods that were used, the largest percentage of stable banks and the smallest percentage of at risk banks was for the soil group with the lowest soil permeability and highest median cohesion values. A comparison of the expected stable bank angles for saturated conditions and the surveyed bank angles indicated that many of the surveyed bank angles were considerably less than the maximum expected stable bank angles despite the banks being classified as at risk or unstable. For severely degraded channels along straight reaches this was not expected. It was expected that they would have angles close to the maximum stable angle as they should have been failing from an oversteepened condition. Several explanations are possible. The channel reaches of some study sites have not yet been affected to a significant degree by degradation; study sites were selected throughout individual basins and severe degradation has not yet extended to some sites along upper reaches; and some reaches have experienced aggradation as degradation progresses upstream. Another possibility is that some bank sections have been affected by lateral migration processes, which typically result in shallow bank angles on the inside bend of the channel. Another possibility is that the maximum expected stable bank angles are too steep. The stability methods used were well established and in essential agreement with each other, and there was no reason to question the geometry data. This left non-representative soil data as a probable reason for computed stable bank angles that, at least in some cases, are overly steep. Based on an examination of the cohesion data, to which the stable bank-angle calculations were most sensitive, both vertical and horizontal variability in soil properti

Water-Resources Investigations Report↗

Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency lakes, Oregon

Upper Klamath Lake and the connecting Agency Lake constitute a large, shallow lake in south-central Oregon that the historical record indicates has likely been eutrophic since its discovery by non-Native Americans. In recent decades, however, the lake has had annual occurrences of near-monoculture blooms of the blue-green alga Aphanizomenon flos-aquae that are thought to be a result of accelerated eutrophication. In 1988, two sucker species endemic to the lake, the Lost River sucker ( Deltistes luxatus ) and the shortnose sucker ( Chasmistes brevirostris ), were listed as endangered by the U.S. Fish and Wildlife Service, and it has been proposed that their decline is due to the poor water quality associated with extremely long and productive algal blooms. It has also been proposed that the effluent drained from wetlands has contributed to accelerated eutrophication. Since the turn of century, most of the wetlands adjacent to Upper Klamath Lake have been drained for agriculture--cultivation of crops and grazing of cattle. Wetland areas were reclaimed from the lake by building dikes to isolate them from the lake, constructing a series of drainage ditches, and installing pumps to drain the water and maintain a lowered water table. A consequence of lowering the water table is the increased ability of air and oxygenated water to move through the subsurface and facilitate the rapid aerobic decomposition of the peat soils. Nutrients, nitrogen and phosphorus, are then liberated, leach into adjacent ditches, and are subsequently pumped to the lake or its tributaries. The rate of peat decomposition may be related to the time since drainage and the type of agricultural land use. On lands cultivated for crops, farming practices, such as disking and furrowing, could enhance the movement of air and oxygenated water, resulting in a rapid rate of decomposition. In contrast, on grazed lands, the compaction of soils by cattle probably inhibits the movement of air and oxygenated water and results in a slower rate of decomposition relative to drained wetlands used for the cultivation of crops. This report presents the results of a cooperative study between the U.S. Geological Survey and the Bureau of Reclamation whose overall objective was to determine the nutrient loading to Upper Klamath Lake from adjacent drained wetlands. Nutrient loading from drained wetlands was estimated using two independent techniques. The first method involved the measurement of the quantity and quality of water discharged by pumps draining the wetlands. The second method was used to estimate the initial (before drainage) and present-day nutrient mass of the organic soils within the drained wetlands and to calculate the change (or loss) in nutrient mass. In an effort to estimate the nutrient contributions from the water pumped off selected drained wetlands adjacent to Upper Klamath Lake, annual loads and yields of total nitrogen and total phosphorus were estimated from concentration data and the volume of water pumped during the water year. In general, there was little variation among sites or among years in the annual total nitrogen (median load of about 18 tons per year and median yield of about 8 pounds per acre per year) or the annual total phosphorus (median load of about 3 tons per year and median yield of about 2 pounds per acre per year) contributions. The sum of the annual loads of nitrogen and phosphorus calculated for each of the pumping stations in 1995 was 80 tons per year and 15 tons per year, respectively. In 1995, soil-coring activities were undertaken to ascertain the nature and extent of the organic soils in the drained and undrained wetlands. The present-day nutrient mass was calculated for each drained wetland using the nutrient content (concentration) and the present-day peat mass. The initial nutrient mass prior to drainage was estimated for each drained wetland by using the initial nutrient content (assumed to be equal to the nutrient content of the undrained wetlands) and the initial peat mass as determined using the amount of accumulated decomposition residue. The cumulative loss of nutrient mass since drainage was calculated as the change between initial and present-day nutrient mass for each drained area. The cumulative yield of total nitrogen and total phosphorus loss from the organic soils of individual wetlands since drainage ranged from 3,000 to 70,000 pounds per acre and from 0 to 1,300 pounds per acre, respectively. For all the drained wetlands sampled, the cumulative nitrogen and phosphorus loss since drainage totaled 250,000 tons and 4,300 tons, respectively. This represents about 30 percent and 22 percent of the mass of nitrogen and phosphorus, respectively, that initially existed in the organic soils. The loss of nutrients from the drained wetlands is considered to be a maximum estimate of the possible contribution of nutrients to Upper Klamath Lake from the peat soils of the drained wetlands sampled. However, not all the nutrients released by the soils are discharged to the lake. Nutrients lost from the peat soils of the drained wetlands may have been taken up by crops and harvested or consumed by grazing cattle. In addition, nitrogen can be lost to the atmosphere by denitrification and the volatilization of ammonia; phosphorus may be bound to adjacent soil layers by adsorption. The annual nutrient loss for the period 1994–95 was calculated using a first-order rate law to describe nutrient loss since drainage began. For individual drained wetlands, the yield of nitrogen and phosphorus lost from the organic soils for the period 1994–95 ranged from 27 to 540 pounds per acre per year and from 0 to 15 pounds per acre per year, respectively. The total mass of nitrogen and phosphorus loss during this period was 3,000 tons per year and 60 tons per year, respectively, for all drained wetlands that were sampled. The yield and mass of nutrient loss determined in this fashion reflect what might be expected on the basis of time-averaged or longterm contributions of nutrients to the lake and do not reflect the specific conditions existing during the period 1994–95. The results of this study could be useful in helping to prioritize which drained wetlands may provide the greatest benefits with regard to reducing nutrient loads to the lake if restoration or land-use modifications are instituted. Recent acquisition and planned restoration of drained wetland areas at the Wood River and Williamson River North properties may produce significant reduction in the quantity of nutrients released by the decomposition of peat soils of these areas. If the water table rises to predrainage levels, the peats soils may become inundated most of the year, resulting in the continued long-term storage of nutrients within the peat soils by reducing aerobic decomposition. The maximum benefit, in terms of decreasing potential nutrient loss due to peat decomposition, could be the reduction of total nitrogen and total phosphorus loss to about one-half that of the 1994–95 annual loss estimated for all the drained wetlands sampled for this study.

Oregon↗

Simulation of a proposed emergency outlet from Devils Lake, North Dakota

From 1993 to 2001, Devils Lake rose more than 25 feet, flooding farmland, roads, and structures around the lake and causing more than $400 million in damages in the Devils Lake Basin. In July 2001, the level of Devils Lake was at 1,448.0 feet above sea level 1 , which was the highest lake level in more than 160 years. The lake could continue to rise to several feet above its natural spill elevation to the Sheyenne River (1,459 feet above sea level) in future years, causing extensive additional flooding in the basin and, in the event of an uncontrolled natural spill, downstream in the Red River of the North Basin as well. The outlet simulation model described in this report was developed to determine the potential effects of various outlet alternatives on the future lake levels and water quality of Devils Lake. Lake levels of Devils Lake are controlled largely by precipitation on the lake surface, evaporation from the lake surface, and surface inflow. For this study, a monthly water-balance model was developed to compute the change in total volume of Devils Lake, and a regression model was used to estimate monthly water-balance data on the basis of limited recorded data. Estimated coefficients for the regression model indicated fitted precipitation on the lake surface was greater than measured precipitation in most months, fitted evaporation from the lake surface was less than estimated evaporation in most months, and ungaged inflow was about 2 percent of gaged inflow in most months. Dissolved sulfate was considered to be the key water-quality constituent for evaluating the effects of a proposed outlet on downstream water quality. Because large differences in sulfate concentrations existed among the various bays of Devils Lake, monthly water-balance data were used to develop detailed water and sulfate mass-balance models to compute changes in sulfate load for each of six major storage compartments in response to precipitation, evaporation, inflow, and outflow from each compartment. The storage compartments--five for Devils Lake and one for Stump Lake--were connected by bridge openings, culverts, or natural channels that restricted mixing between compartments. A numerical algorithm was developed to calculate inflow and outflow from each compartment. Sulfate loads for the storage compartments first were calculated using the assumptions that no interaction occurred between the bottom sediments and the water column and no wind- or buoyancy-induced mixing occurred between compartments. However, because the fitted sulfate loads did not agree with the estimated sulfate loads, which were obtained from recorded sulfate concentrations, components were added to the sulfate mass-balance model to account for the flux of sulfate between bottom sediments and the lake and for mixing between storage compartments. Mixing between compartments can occur during periods of open water because of wind and during periods of ice cover because of water-density differences between compartments. Sulfate loads calculated using the sulfate mass-balance model with sediment interaction and mixing between compartments closely matched sulfate loads computed from historical concentrations. The water and sulfate mass-balance models were used to calculate potential future lake levels and sulfate concentrations for Devils Lake and Stump Lake given potential future values of monthly precipitation, evaporation, and inflow. Potential future inputs were generated using a scenario approach and a stochastic approach. In the scenario approach, historical values of precipitation, evaporation, and inflow were repeated in the future for a particular sequence of historical years. In the stochastic approach, a statistical time-series model was developed to randomly generate potential future inputs. The scenario approach was used to evaluate the effectiveness of various outlet alternatives, and the stochastic approach was used to evaluate the hydrologic and water-quality effects of the potential outlet alternatives that were selected on the basis of the scenario analysis. Given potential future lake levels and sulfate concentrations generated using either the scenario or stochastic approach and potential future ambient flows and sulfate concentrations for the Sheyenne River receiving waters, daily outlet discharges could be calculated for virtually any outlet alternative. For the scenario approach, future ambient flows and sulfate concentrations for the Sheyenne River were generated using the same sequence of years used for generating water-balance data for Devils Lake. For the stochastic approach, a procedure was developed for generating daily Sheyenne River flows and sulfate concentrations that were "in-phase" with the generated water-balance data for Devils Lake. Simulation results for the scenario approach indicated that neither of the West Bay outlet alternatives provided effective flood-damage reduction without exceeding downstream water-quality constraints. However, both Pelican Lake outlet alternatives provided significant flood-damage reduction with only minor downstream water-quality changes. The most effective alternative for controlling rising lake levels was a Pelican Lake outlet with a 480-cubic-foot-per-second pump capacity and a 250-milligram-per-liter downstream sulfate constraint. However, this plan is costly because of the high pump capacity and the requirement of a control structure on Highway 19 to control the level of Pelican Lake. A less costly, though less effective for flood-damage reduction, plan is a Pelican Lake outlet with a 300-cubic-foot-per-second pump capacity and a 250-milligram-per-liter downstream sulfate constraint. The plan is less costly because the pump capacity is smaller and because the control structure on Highway 19 is not required. The less costly Pelican Lake alternative with a 450-milligramper- liter downstream sulfate constraint rather than a 250-milligram-per-liter downstream sulfate constraint was identified by the U.S. Army Corps of Engineers as the preferred alternative for detailed design and engineering analysis. Simulation results for the stochastic approach indicated that the geologic history of lake-level fluctuations of Devils Lake for the past 2,500 years was consistent with a climatic history that consisted of two climate states--a wet state, similar to conditions during 1980-99, and a normal state, similar to conditions during 1950-78. The transition times between the wet and normal climatic periods occurred randomly. The average duration of the wet climatic periods was 20 years, and the average duration of the normal climatic periods was 120 years. The stochastic approach was used to generate 10,000 independent sequences of lake levels and sulfate concentrations for Devils Lake for water years 2001-50. Each trace began with the same starting conditions, and the duration of the current wet cycle was generated randomly for each trace. Each trace was generated for the baseline (natural) condition and for the Pelican Lake outlet with a 300-cubic-foot-per-second pump capacity and a 450-milligram-per-liter downstream sulfate constraint. The outlet significantly lowered the probabilities of future lake-level increases within the next 50 years and did not substantially increase the probabilities of reaching low lake levels or poor water-quality conditions during the same period.

Water-Resources Investigations Report↗

Surface-water-quality assessment of the Yakima River basin, Washington: Overview of major findings, 1987-91

Surface-water-quality conditions were assessed in the Yakima River Basin, which drains 6,155 square miles of mostly forested, range, and agricultural land in Washington. The Yakima River Basin is one of the most intensively farmed and irrigated areas in the United States, and is often referred to as the “Nation’s Fruitbowl.” Natural and anthropogenic sources of contaminants and flow regulation control water-quality conditions throughout the basin. This report summarizes the spatial and temporal distribution, sources, and implications of the dissolved oxygen, water temperature, pH, suspended sediment, nutrient, organic compound (pesticide), trace element, fecal indicator bacteria, radionuclide, and aquatic ecology data collected during the 1987–91 water years. The Yakima River descends from a water surface altitude of 2,449 feet at the foot of Keechelus Dam to 340 feet at its mouth downstream from Horn Rapids Dam near Richland. The basin can be divided into three distinct river reaches on the basis of its physical characteristics. The upper reach, which drains the Kittitas Valley, has a high gradient, with an average streambed slope of 14 feet per mile (ft/mi) over the 74 miles from the foot of Keechelus Dam (river mile [RM] 214.5) to just upstream from Umtanum. The middle reach, which drains the Mid Valley, extends a distance of 33 miles from Umtanum (RM 140.4) to just upstream from Union Gap and also has a high gradient, with an average streambed slope of 11 ft/mi. The lower reach of the Yakima River drains the Lower Valley and has an average streambed slope of 7 ft/mi over the 107 miles from Union Gap (RM 107.2) to the mouth of the Yakima River. These reaches exhibited differences in water-quality conditions related to the differences in geologic sources of contaminants and land use. Compared with the rest of the basin, the Kittitas Valley and headwaters of the Naches River Subbasin had relatively low concentrations and loads of suspended sediment, nutrients, organic compounds, and fecal indicator bacteria. There were very few failures to meet the Washington State dissolved oxygen standard or exceedances of the water temperature and pH standards in this reach. In general, these areas are considered to be areas of lessdegraded water quality in the basin. The preTertiary metamorphic and intrusive rocks of the Cle Elum and Teanaway River Subbasins, however, were found to be significant geologic sources of antimony, arsenic, chromium, copper, mercury, nickel, selenium, and zinc. As a result, the arsenic, chromium, and nickel concentrations measured in the streambed sediment of the Kittitas Valley were 13 to 74 times higher than those measured in the Lower Valley. The Mid and Lower Valleys had similar water-quality conditions, governed by the intensive agricultural and irrigation activities, highly erosive landscapes, and flow regulation. Most of the failures to meet the Washington State standards for dissolved oxygen and exceedances of the standards for water temperature and pH occurred in the Mid and Lower Valleys. Agricultural drains in the Mid and Lower Valleys were found to be significant sources of nutrients, suspended sediment, pesticides, and fecal indicator bacteria. Downstream from the irrigation diversions near Union Gap, summertime streamflow in the Yakima River was drastically reduced to only a few hundred cubic feet per second. In the lower Yakima River, agricultural return flow typically accounts for as much as 80 percent of the main stem summertime flow near the downstream terminus of the basin. Therefore, the water-quality characteristics of the lower Yakima River resemble those of the agricultural drains. The highest fecal bacteria concentrations (35,000 colonies of Escherichia coli per 100 milliliters of water) were measured in the Granger/Sunnyside area, the location of most of the livestock in the basin. The east side area of the Lower Valley (area east of the Yakima River) was the predominant source area for suspended sediment and pesticides in the basin. This area had the largest acreage of irrigated land and generally received the largest application of pesticides. Owing to the highly erosive soils of the area, the suspended sediment load from the east side in June 1989 (320 kilograms per day) was five or more times larger than from any other area, and the loads of several of the more hydrophobic organic compounds were four or more times larger. An ecological assessment of the Yakima River Basin ranked physical, chemical, and biological conditions at impaired (degraded) sites against reference sites in an effort to understand how land use changes physical and chemical site characteristics and how biota respond to these changes. For this assessment, the basin was divided into four natural ecological categories: (1) Cascades ecoregion, (2) Eastern Cascades Slopes and Foothills ecoregion, (3) Columbia Basin ecoregion, and (4) large rivers. Each of these categories has a unique combination of climate and landscape features that produces a distinctive terrestrial vegetation assemblage. In the combined Cascades and Eastern Cascades site group, which had the fewest impaired sites, the metals index was the only physical and chemical index that indicated any impairment. The moderate levels of impairment noted in the invertebrate and algal communities were not, however, associated with metals, and may have been related to the effects of logging, although the intensity of logging was not directly quantified in this study. Sites in the Columbia Basin site group were all moderately or severely impaired with the exception of the two reference sites (Umtanum Creek and Satus Creek below Dry Creek), which showed no physical, chemical, or biological impairment. Three sites were heavily affected by agriculture (Granger Drain, Moxee Drain, and Spring Creek) and were listed as severely impaired by most of the physical, chemical, and biological condition indices. Agriculture was the primary cause of the impairment of biological communities in this site group. The primary physical and chemical indicators of agricultural effects were nutrients, pesticides, dissolved solids, and substrate embeddedness, which all tended to increase with agricultural intensity. The biological effects of agriculture were manifested by a decrease in the abundance and number of native species of fish and invertebrates, a shift in algal communities to species indicative of eutrophic conditions, and higher abundances. There was also an increase in the abundance and number of nonnative fish species due to the prevalence of fish that are largely tolerant of nutrient-rich conditions. Main stem (large river) sites downstream from the city of Yakima exhibited severe impairment of fish communities associated with high levels of pesticides in fish tissues and the presence of external anomalies on fish.

Washington↗

Effects of runoff controls on the quantity and quality of urban runoff at two locations in Austin, Texas

Rapid urban development in the Austin metropolitan area, Texas, is causing concern about increasing peak discharges from storm runoff and the degradation of the quality of water in receiving streams, lakes, and aquifers. In an attempt to decrease peak discharges and improve water quality, runoff controls are being required in some watersheds. This report summarizes the precipitation, streamflow, and water-quality data collected from September 1982 to September 1984 upstream and downstream from runoff controls at two locations, and presents the effects of these runoff controls on streamflow and the quality of runoff water. The two controls are a detention and filtering pond near Barton Creek Square Shopping Center, a large shopping center southwest of downtown Austin, and a grass-swale control in the Al ta Vista Planned Unit Development, a multipie-family housing area. At Barton Creek Square Shopping Center, rainfall for the storms analyzed ranged from 0.14 to 2.88 inches. The rainfall rate for the September 7, 1983, storm exceeded the 100-year return period for the 5- and 10-minute duration and was equal to the 50-year return period for the 15-minute duration. Peak discharge at the inflow station to the detention pond was closely related to the maximum rainfall during a 5-minute period and occurred about 10 minutes later. The maximum inflow at this station was 185 cubic feet per second and appeared to be the limit of the storm sewer system. For small- and moderate-sized storms, the runoff is contained in the detention pond and passes through a filter system. Runoff from large storms overflows into the drop outlet. For storms contained in the pond, peak discharges at the outflow station generally were less than 3.1 cubic feet per second. As time passed, the outflow peak discharges tended to decrease as a result of reduced permeability of the filter. Cleaning the filter appeared to increase the peak flows but did not restore them to the previous level. The runoff-rainfall ratio averaged 0.85 at the inflow station and 0.36 at the outflow station. A water budget shows unexplained losses to average 20 percent. At the Barton Creek Square Shopping Center, discharge-weighted densities of fecal-col iform and fecal-streptococci bacteria and discharge-weighted concentrations of biochemical oxygen demand, chemical oxygen demand, total organic carbon, suspended solids, total ammonia plus organic nitrogen, and total phosphorus generally were larger in the inflow than in the outflow. Discharge-weighted concentrations of dissolved lead, dissolved iron, and dissolved zinc generally were small in both the inflow and outflow; however, the larger discharge-weighted concentrations of these constituents generally were found in the inflow. Discharge-weighted concentrations of volatile dissolved solids were smaller in the inflow than in the outflow for 10 of the 22 storms analyzed. Discharge-weighted concentrations of total nitrite plus nitrate nitrogen and dissolved solids generally were much smaller in the inflow than in the outflow. It is likely that organic and ammonia nitrogen trapped in the pond from previous storms and in the inflow water as it flows through the pond is being oxidized to nitrite and nitrate nitrogen. Similarly, dissolved solids retained in the filter or on the bed of the pond from previous storms are being leached to the outflow. Measured peak concentrations or densities of most constituents in the inflow were significantly larger than those in the outflow for most constituents. An exception was noted for concentrations of total nitrite plus nitrate which were larger in the outflow than the inflow as indicated by discrete sample analysis for six storms. Loads of most constituents and total numbers of bacteria were significantly larger in the inflow than in the outflow. The total numbers of bacteria were reduced by approximately 80 percent. Average removal efficiencies for suspended solids, biochemical oxygen demand, total phosphorus, total organic carbon, chemical oxygen demand, and dissolved zinc ranged between 60 and 80 percent. The average loads of dissolved solids were approximately 13 percent larger in the outflow than the inflow. Average loads of total nitrite plus nitrate nitrogen were approximately 110 percent larger in the outflow than in the inflow. The increase in loads of these constituents is due to material being leached from the bed of the pond or from the filter system. At Al ta Vista, rainfall for the storms analyzed ranged from 0.25 to 2.00 inches. The maximum rainfall intensity was 0.30 inch for a 5-minute interval. The runoff-rainfall ratio averaged 0.42 and appeared to be evenly distributed about the mean ratio line. The peak discharge at the inflow station to the grass-covered swale area was 0.93 cubic foot per second. Inaccuracies of discharge at the outflow station and variations in the ungaged drainage area with the size of the storm prevented a hydrologic analysis of the basin above this station. Discharge-weighted concentrations of total phosphorus were larger in the outflow than in the inflow for each of the 19 storms analyzed. Discharge-weighted concentrations of dissolved solids, volatile dissolved solids, biochemical oxygen demand, chemical oxygen demand, and total organic carbon were larger in the outflow than in the inflow for at least 12 of the 19 storms analyzed. Discharge-weighted densities of fecal streptococci were decreased between the inflow and outflow, with discharge-weighted densities of fecal streptococci being less in the outflow for 15 of the 19 storms analyzed. Because of the relatively small variations in concentrations and densities of constituents between the inflow and outflow sites, and because of the errors in discharge at the outflow gage, it is not feasible to determine the effect of the grass-covered swales on discharge-weighted concentrations and densities of water-quality constituents. Discrete concentrations or densities of most constituents were not decreased. Peak concentrations of dissolved solids in the outflow exceeded peak concentrations in the inflow for all five of the storms analyzed with discrete samples. Peak concentrations of suspended solids, total ammonia plus organic nitrogen, total nitrite plus nitrate nitrogen, total nitrogen, and dissolved iron were larger in the outflow than in the inflow for four of the five storms analyzed. Load-removal efficiencies of water-quality constituents could not be determined because of inaccuracies in measuring discharge at the outflow site,

Texas↗

Water resources investigation program for Rio Aconcagua Valley, Chile

This report, prepared at the request of the Government of Chile under the auspices of the U. S. Agency for International Development (US AID), is based on a 2-month assignment (Oct. 22 to Dec. 31, 1969) of the author and outlines a program of water resources studies. The study program, if followed to its conclusion, will provide the basic hydrologic and hydrogeologic information and analysis essential for planning optimum future development and use of the water resources of the valley.

Open-File Report↗

Water levels in observation wells in Santa Barbara County, California, in 1956

Investigation of the ground-water resources of Santa Barbara County was continued during 1956 by the Geological Survey in cooperation with the Santa Barbara County Water Agency. Monthly water-level recorders were operated. Earlier measurements, covering the period 1941 through 1953, have been published in Geological Survey water-Supply Papers; those for 1954 and 1955 are in press and have been released locally in duplicated form. Water-Supply Paper 1068 contains tabulated descriptions of 2,246 wells in existence in 1942 in the various ground-water basins of the county. The same publication contains also many water-level measurements made prior to 1942 by the city of Santa Barbara, Santa Maria Valley Water Conservation District, San Joaquin Power Division of the Pacific Gas and Electric Co., Union Sugar Co., Union Oil Co., and other organizations and individuals. Comprehensive reports on the geology and ground-water resources of the Santa Ynez River basin (Upson and Thomasson, 1951), the south-coast basins (Upson, 1951), the Santa Maria Valley area (Worts, 1951), and the Cuyama Valley (Upson and Worts, 1951) have been published as Water-Supply Papers 1107, 1108, 1000, and 1110-B respectively. A report on stream runoff and ground-water storage capacity of the Santa Ynez River valley (Troxell and Wilson, 1952) was released to the open file in October 1952. A report appraising the ground-water resources of the Santa Ynez River valley (Wilson, 1957) was released to the open file in October 1956.

California↗

Instructions for flood frequency compilations

These instructions are designed to facilitate work in this field, but are not to be considered as final and complete. They will be revised as needed to incorporate new ideas and experience gained in this field. For that reason, if use is planned any great period after the date shown on the cover, write the Chief Hydraulic Engineer for advice as to changes. Comments are always welcome.

Report↗

Hydrologic data for water-management plans—A resource for Tribal Governments in Oklahoma

Introduction The major streams in Oklahoma, and the alluvial aquifers associated with those major streams, are important resources for the 39 federally recognized Tribes in Oklahoma. Many Tribal Governments are interested in developing water-management plans (hereinafter referred to as “water plans”) to preserve water resources for the future. This report provides a general overview of the types of information and data needed to prepare comprehensive water plans. To assist Tribes in the development of water plans, the U.S. Geological Survey, in cooperation with the Bureau of Indian Affairs, has outlined the steps necessary for creation of such plans.

Oklahoma↗

Hydrologic and geologic aspects of waste management and disposal; a bibliography of publications by U.S. Geological Survey authors, 1950-81

References to more than 550 reports, articles, and maps are listed alphabetically by author and are indexed by subject. The subject index includes geographic-area terms. Citations from 69 series are included; series are listed separately. The publications listed report the results of U.S. Geological Survey research and field projects throughout the Nation concerning earth-science aspects of waste management and disposal. They include organic, inorganic, and radioactive wastes and related topics such as mathematical models of solute transport. Most of the references are to (1) Geological Survey report series such as Water-Supply Papers, Professional Papers, Bulletins, Circulars, Water-Resources Investigations, and Open-File Reports, (2) technical journals of professional organizations, or (3) reports by other Federal and State agencies.

Circular↗