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USGS2002

Hydrology and Water Quality of the Grand Portage Reservation, Northeastern Minnesota, 1991-2000

The Grand Portage Reservation is located in northeastern Cook County, Minnesota at the boundary between Minnesota, USA, and Ontario, Canada. Between 1991 and 2000 the U.S. Geological Survey conducted a series of studies, with the cooperation with Grand Portage Band of Chippewa, to describe the water resources of the Grand Portage Reservation. Ground water moves primarily through fractures in the bedrock, probably in three ground-water systems: local, regional, and deep. Lake Superior is thought to be the discharge point for brines in the deep ground-water flow system. The watersheds in the Grand Portage Reservation are small and steep; consequently streams in the Grand Portage Reservation tend to be flashy. Lake stages rise and fall with rainfall. The pH of water in the Reservation is generally alkaline (pH greater than 7.0). The alkalinity of water in the Reservation is low. Concentrations of major ions are much greater in ground water than in spring water and surface water. The ionic composition of water in the Reservation differs depending upon the source of the water. Water from 11 of the 20 wells sampled are a calcium-sodium-chloride type. Water from wells GW-2, GW-7, and GW-11 had much greater specific conductance concentrations of major ions compared to the other wells. Some spring water (SP-1, SP-3, SP-4, SP-6, and SP-8) is calcium-bicarbonate type like surface water, whereas other spring water (SP-5 and SP-7) is similar to the calcium-sodium-chloride type occurring in samples from about one-half the wells. The major chemical constituents in surface water are bicarbonate, calcium, and magnesium. Measured tritium and sulfur hexafluoride (SF6) concentrations in water samples from springs and wells were used to determine the recharge age of the sampled water. The recharge ages of two of the wells sampled for tritium are before 1953. The recharge ages of the remaining 10 samples for tritium are probably after 1970. The recharge ages of seven SF6 samples were between 1973 and 1998.

Minnesota↗
USGS2002

Estimating the magnitude of peak flows at selected recurrence intervals for streams in Idaho

Methods for estimating magnitudes of peak flows at various recurrence intervals, needed for highway-structure and water-control design and planning, were developed for gaged and ungaged sites on streams throughout Idaho. Recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years were selected for analysis of peak flows. For gaged sites in Idaho, peak-flow estimates were calculated by fitting a log-Pearson Type III distribution to the annual peak-flow data for each site. Annual peak flows through 1997 were used in the analysis. Basin and climatic characteristics for these gaged sites were calculated from 1:24,000 digitalelevation models and various thematic data coverages using a geographic information system. Peak- flow data and basin and climatic characteristics for 333 gaged sites were combined to develop a database that was used for the analysis. To estimate the magnitude of peak flows at ungaged sites near gaged sites on the same stream, a method was developed on the basis of drainage-area ratios. To estimate the magnitude of peak flows for ungaged sites on unregulated and undiverted streams, two regional regression methods were developed. The first regression method, termed the regional regression method, used generalized least-squares regression to develop a set of predictive equations for estimating peak flows at selected recurrence intervals for seven hydrologic regions in Idaho. These regional regression equations related basin and climatic characteristics to peak flows. The regional regression equations were all functions of drainage area plus one or two other basin characteristics. Average errors of prediction for these regression equations ranged from +143 percent to 58.8 percent. The range of errors was narrowest, from about +51.9 to about 34.2, for region 5. Error ranges were usually narrower for the middle recurrence intervals than for the lower and upper recurrence intervals. A computer program was developed to calculate the magnitude of peak flows at each recurrence interval, the average error of prediction, and the 90-percent confidence interval for each ungaged site. The second regression method, termed the region-of-influence method, was used to develop a unique regression equation for each estimate that is based on a subset of gaged sites with values of basin and climatic characteristics similar to those for the ungaged sites. All 333 gages in the database were used to select the subset. Root-mean-squared errors for this method ranged from 55.5 percent to 72.4 percent. Differences in root-mean-squared errors between regional regression equations and the region-of-influence method were quite large. The average difference in root-mean-squared errors for the region-of-influence method was more than 10 percent greater than the average differences for the regional regression equations. For region 5, the average difference was greater than 20 percent. However, for region 8, the root-mean-squared errors were, in general, only slightly smaller for the region-of-influence method than for the regional regression equations. The region-of-influence method is not recommended for use in determining flood-frequency estimates for ungaged sites in Idaho because the results, overall, are less accurate and the calculations are more complex than those of regional regression equations. The regional regression equations were considered to be the primary method of estimating the magnitude and frequency of peak flows for ungaged sites in Idaho.

Idaho;Montana;Nevada;Oregon;Washington;Wyoming↗
USGS2002

Water-quality assessment of the Rio Grande Valley, Colorado, New Mexico, and Texas — Surface-water quality, shallow ground-water quality, and factors affecting water quality in the Rincon Valley, south-central New Mexico, 1994-95

As part of the National Water-Quality Assessment Program, surface-water and ground-water samples were collected in 1994 and 1995 for analysis of common constituents, nutrients, dissolved organic carbon, trace elements, radioactivity, volatile organic compounds, and pesticides to characterize surface water quality and shallow ground-water quality and to determine factors affecting water quality in the Rincon Valley, south-central New Mexico. Samples of surface water were collected from three sites on the Rio Grande and from sites on three agricultural drains in the Rincon Valley in January 1994 and 1995, April 1994, and October 1994Ground-water samples were collected in late April and early May 1994 from 30 shallow wells that were installed during the investigation. Dissolved-solids concentrations in surface water ranged from 434 to 1,510 milligrams per liter (mg/L). Dissolved-solids concentrations were smallest in water from the Rio Grande below Caballo Dam and largest in the drains. Nitrite plus nitrate concentrations ranged from less than 0.05 to 3.3 mg/L as nitrogen, and ammonia concentrations ranged from less than 0.015 to 0.33 mg/L as nitrogen in surface-water samples. Trace-element concentrations in surface water were significantly smaller than the acute-fisheries standards. One or more pesticides were detected in 34 of 37 surface-water samples. DCPA (dacthal) and metolachlor were the most commonly detected pesticides. No standards have been established for the pesticides analyzed for in this study. Dissolved-solids concentrations in shallow ground water ranged from 481 to 3,630 mg/L. All but 2 of 30 samples exceeded the secondary maximum contaminant level for dissolved solids of 500 mg/L. Water from about 73 percent of the wells sampled exceeded the secondary maximum contaminant level of 250 mg/L for sulfate, and water from about 7 percent of the wells sampled exceeded the secondary maximum contaminant level of 250 mg/L for chloride. Nitrite plus nitrate concentrations ranged from less than 0.05 to 33 mg/L as nitrogen in shallow ground water. Water from about 17 percent of the well samples exceeded the maximum contaminant level of 10 mg/L as nitrogen for nitrite plus nitrate. Trace-element concentrations in shallow ground water generally were small (1 to 10 micrograms per liter)The proposed maximum contaminant level of 20 micrograms per liter for uranium was exceeded in about 13 percent of the samples. The secondary maximum contaminant level of 300 micrograms per liter for iron was exceeded in about 17 percent of the samples and of 50 micrograms per liter for manganese was exceeded in about 83 percent of the samples. Samples from about 23 percent of the wells exceeded the maximum contaminant level of 15 picocuries per liter for gross alpha activity. One or more pesticides were detected in water from 12 of 30 wells sampled. The pesticides or pesticide metabolites diazinon, metolachlor, napropamide, p,p’-DDE, and prometon were detected in one or more samples. Metolachlor and prometon were the most commonly detected pesticides. Health advisories for the pesticides detected in shallow ground water (no maximum contaminant levels have been established for the pesticides detected) are 10 to 300 times larger than the concentrations detected. Infiltration, evaporation, and transpiration of irrigation water are important factors affecting the concentrations of common constituents in shallow ground water in the Rincon Valley. Dissolution and precipitation of minerals and mixing of shallow ground water and inflow of ground water from adjacent areas also affect the composition of shallow ground water and water in the drains. Relatively large nitrite plus nitrate concentrations in several shallow ground-water samples indicate leaching of fertilizers in some areas of the Rincon Valley. Molybdenum and uranium concentrations in part of the Rincon Valley are affected by inflow of ground water to the valley from adjacent areas. A large amount of the gross alpha activity in shallow ground water is from uranium isotopes. Gross beta activity increases with dissolved potassium, indicating that part of the dissolved gross beta activity is from potassium-40. The detection of a larger number of different pesticides in surface water than in ground water indicates that pesticides are entering surface water as runoff from fields or that the number of ground-water samples collected and the time of year that the samples were collected did not adequately represent the composition of ground water in the Rincon Valley that discharges to the drains. On the basis of pesticide concentrations detected in shallow ground water in the Rincon Valley, large amounts of the pesticides analyzed for are not leaching from land surface into ground water. There is some indication that several pesticides are leaching downward into shallow ground water (metolachlor and prometon especially); however, the concentrations detected in shallow ground water are significantly smaller than any standards or health advisories issued by the U.S. Environmental Protection Agency.

New Mexico↗
USGS2002

Observed and predicted pier scour in Maine

Pier-scour and related data were collected and analyzed for nine high river flows at eight bridges across Maine from 1997 through 2001. Six bridges had multiple piers. Fifteen of 23 piers where data were measured during a high flow had observed maximum scour depths ranging from 0.5 feet (ft) to 12.0 ft. No pier scour was observed at the remaining eight piers. The maximum predicted pier-scour depths associated with the 23 piers were computed using the equations in the Federal Highway Administration's Hydraulic Engineering Circular number 18 (HEC-18), with data collected for this study. The predicted HEC-18 maximum pier-scour depths were compared to the observed maximum pier-scour depths. The HEC-18 pier-scour equations are intended to be envelope equations, ideally never underpredicting scour depths and not appreciably overpredicting them. The HEC-18 pier-scour equations performed well for rivers in Maine. Twenty-two out of 23 pier-scour depths were overpredicted by 0.7 ft to 18.3 ft. One pier-scour depth was underpredicted by 4.5 ft. For one pier at each of two bridges, large amounts of debris lodged on the piers after high-flow measurements were made at those sites. The scour associated with the debris increased the maximum pier-scour depths by about 5 ft in each case.

Maine↗
USGS2002

Stream-aquifer relations and the potentiometric surface of the Upper Floridan aquifer in the lower Apalachicola-Chattahoochee-Flint River basin in parts of Georgia, Florida, and Alabama, 1999-2000

The Upper Floridan aquifer is the principal source of water for domestic and agricultural use in the lower Apalachicola-Chattahoochee-Flint (ACF) River Basin. Recent drought and increased water use have made understanding surface- and ground-water relations a priority for water-resource managers in the region. From July 1999 through August 2000, less than normal precipitation reduced streamflow in the area to less than 12 percent of average mean-daily streamflow and ground-water levels reached record or near-record lows. Effects of drought on stream-aquifer interactions in the basin were evaluated using baseflow estimation, ground-water seepage calculations, and potentiometric-surface maps. Ground-water discharge to streams, or baseflow, was estimated using three methods: field measurements, hydrograph separation, and linear regression analysis. Results were evaluated seasonally -- October 1999, April 2000, and August 2000 -- and for the period of record at four surface-water stations located on Kinchafoonee, Spring, Muckalee, and Turkey Creeks. Estimates of baseflow also were compared annually; ground-water discharge during the drought years, 1999 - 2000, was compared with ground-water discharge during a relatively wet year, 1994. Hydrograph separation indicated decreased base-flow of streams as the water level in the Upper Floridan aquifer declined. Mean-annual baseflow for Kinchafoonee, Spring, Muckalee, and Turkey Creeks ranged from 36 to 71 percent of total streamflow during the period of record. In 1994 baseflow accounted for only 37 to 56 percent of total streamflow, in 1999 baseflow comprised from 60 to 73 percent of total streamflow, and in 2000 baseflow comprised from 56 to 76 percent of streamflow. The percentage of total streamflow attributed to ground water increased during the drought, whereas other components of streamflow decreased (overland flow, interflow, and channel precipitation). Even though relative ground-water contributions were increased, the volume of water discharged from the aquifer to streams decreased during the drought as the Upper Floridan aquifer water level declined. Unit-area mean-annual ground-water discharge ranged from 0.60 to 0.79 cubic foot per second per square mile ([ft 3 /s]/mi2) in 1994, from 0.24 to 0.58 (ft 3 /s)/mi2 in 1999, and from 0.13 to 0.33 (ft 3 /s)/mi2 in 2000. Ground-water contributions to streamflow are high in winter, when evaporative demands are low, and low in summer, when evaporative demands are high. Linear regression analysis of stream-aquifer relations in the lower ACF River Basin shows 85- or 90-percent flow durations as reasonable estimates of baseflow.

Alabama, Florida, Georgia↗
USGS2002

Trends in Streamflow, River Ice, and Snowpack for Coastal River Basins in Maine During the 20th Century

Trends over the 20th Century were examined in streamflow, river ice, and snowpack for coastal river basins in Maine. Trends over time were tested in the timing and magnitude of seasonal river flows, the occurrence and duration of river ice, and changes in snowpack depth, equivalent water content, and density. Significant trends toward earlier spring peak flow and earlier center-of-volume runoff dates were found in the extended streamflow record spanning 1906-21 and 1929-2000. Only one of the six coastal rivers in the study analyzed for trends in cumulative runoff had a significant change in total annual runoff volume. Last spring river-ice-off dates at most coastal streamflow-gaging stations examined are trending to earlier dates. Trends in later fall initial onset of ice also are evident, although these trends are significant at fewer stations than that observed for ice-off dates. Later ice-on dates in the fall and (or) earlier ice-off dates in the spring contribute to a statistically significant decrease over time in the total number of days of ice occurrence at most gaging stations on coastal rivers in Maine. The longest, most complete snow records in coastal Maine indicate an increase in snow density for the March 1 snow-survey date during the last 60 years. The historical trends in streamflow, ice, and snow are all consistent with an earlier onset of hydrologic spring conditions in coastal Maine.

Water-Resources Investigations Report↗
USGS2003

Nutrients in Shallow Ground Waters Beneath Relatively Undeveloped Areas in the Conterminous United States

Nutrient concentrations in shallow (well depth of 30 meters or less) ground waters of relatively undeveloped areas were evaluated to determine background conditions relative to agricultural and urban land uses. Lands comprising 67 percent or greater forest or range, 10 percent or less agricultural land, and 10 percent or less urban land were used to represent relatively undeveloped areas. Data subsets from the U.S. Geological Survey's National Water-Quality Assessment Program (81 wells) and retrospective studies (320 wells) yielded 75th percentile nitrate concentrations of 0.51 and 1.1 milligrams per liter, respectively, in shallow ground water beneath relatively undeveloped areas. The value of 1.1 milligrams per liter is a reasonable upper bound estimate of relative background concentration of nitrate in shallow ground waters in the United States and incorporates effects of nominal nitrogen load to susceptible aquifers. Relative background concentration of nitrate is variable and depends in part on land use, rock type, and climate. Median nitrate concentration was significantly greater in ground water beneath rangeland (1.20 milligrams per liter) than beneath forest land (0.06 milligram per liter). Median nitrate concentration in ground water beneath rangeland was 1.4-2.7 milligrams per liter in susceptible aquifers, which consist of coarse-textured deposits or fractured rock. Increased relative background concentration of nitrate in rangeland areas likely results from evaporative concentration of nominal nitrogen load associated with natural organic and inorganic sources in hydrogeologically susceptible settings.

Water-Resources Investigations Report↗
USGS2002

Estimates of median flows for streams on the Kansas surface water register

The Kansas State Legislature, by enacting Kansas Statute KSA 82a-2001 et. seq., mandated the criteria for determining which Kansas stream segments would be subject to classification by the State. One criterion for the selection as a classified stream segment is based on the statistic of median flow being equal to or greater than 1 cubic foot per second. As specified by KSA 82a-2001 et. seq., median flows were determined from U.S. Geological Survey streamflow-gaging-station data by using the most-recent 10-years of gaged data (KSA) for each streamflow-gaging station. Median flows also were determined by using gaged data from the entire period of record (all-available hydrology, AAH). Least-squares multiple regression techniques were used, along with Tobit analyses, to develop equations for estimating median flows for uncontrolled stream segments. The drainage area of the uncontrolled gaging stations used in the regression analyses ranged from 2.06 to 12,004 square miles. A logarithmic transformation of the data was needed to develop the best linear relation for computing median flows. In the regression analyses, the significant climatic and basin characteristics, in order of importance, were drainage area, mean annual precipitation, mean basin permeability, and mean basin slope. Tobit analyses of KSA data yielded a root mean square error of 0.285 logarithmic units, and the best equations using Tobit analyses of AAH data had a root mean square error of 0.247 logarithmic units. These equations and an interpolation procedure were used to compute median flows for the uncontrolled stream segments on the Kansas Surface Water Register. Measured median flows from gaging stations were incorporated into the regression-estimated median flows along the stream segments where available. The segments that were uncontrolled were interpolated using gaged data weighted according to the drainage area and the bias between the regression-estimated and gaged flow information. On controlled reaches of Kansas streams, the median flow information was interpolated between gaging stations using only gaged data weighted by drainage area. Of the 2,232 total stream segments on the Kansas Surface Water Register, 30 percent of the segments had an estimated median streamflow of less than 1 cubic foot per second when the KSA analysis was used. When the AAH analysis was used, 40 percent of the segments had an estimated median streamflow of less than 1 cubic foot per second.

Kansas↗
USGS2003

Land Use on the Island of Oahu, Hawaii, 1998

A hierarchical land-use classification system for Hawaii was developed, and land use on the island of Oahu was mapped. The land-use classification system emphasizes agriculture, developed (urban), and barren/mining uses. Areas with other land uses (conservation, forest reserve, natural areas, wetlands, water, and barren [sand, rock, or soil] regions, and unmanaged vegetation [native or exotic]) were defined as 'other.' Multiple sources of digital orthophotographs from 1998 and 1999 were used as source data. The 1998 island of Oahu land-use data are provided in digital format at http://water.usgs.gov/lookup/getspatial?oahu_lu98 for use in a Geographic Information System (GIS), at 1:24,000-scale with minimum mapping units of 2 hectares (4.9 acres) area and 30-meters (98.4 feet) feature width. In 1998, a total of 59,195 acres (15.4 percent) of the island of Oahu were classified as agricultural land use; 98,663 acres (25.7 percent) were classified as developed; 1,522 acres (0.4 percent) were classified as barren/mining; and 224,331 acres (58.5 percent) were classified as other. An accuracy assessment identified 98 percent accuracy for all land-use classes. In windward (moister) areas, dense vegetation and canopy cover along with rapid recolonization by vegetation potentially obscured land use from photo-interpretation. While in leeward (drier) areas, sparse vegetative cover and slower vegetation recolonization may have resulted in more frequent recognition of apparent land-use patterns.

Water-Resources Investigations Report↗
USGS2003

Simulation of the Ground-Water Flow System in 1992, and Simulated Effects of Projected Ground-Water Withdrawals in 2020 in the New Jersey Coastal Plain

In 1992, ground-water withdrawals from the unconfined and confined aquifers in the New Jersey Coastal Plain totaled about 300 million gallons per day, and about 70 percent (200 million galllons per day) of this water was pumped from confined aquifers. The withdrawals have created large cones of depression in several Coastal Plain aquifers near populated areas, particularly in Camden and Ocean Counties. The continued decline of water levels in confined aquifers could cause saltwater intrusion, reduction of stream discharge near the outcrop areas of these aquifers, and depletion of the ground-water supply. Because of this, withdrawals from wells located within these critical areas have been reduced in the Potomac-Raritan-Magothy aquifer system, the Englishtown aquifer system, and the Wenonah-Mount Laurel aquifer. A computer-based model that simulates freshwater and saltwater flow was used to simulate transient ground-water flow conditions and the location of the freshwater-saltwater interface during 1989-92 in the New Jersey Coastal Plain. This simulation was used as the baseline for comparison of water levels and flow budgets. Four hypothetical withdrawal scenarios were simulated in which ground-water withdrawals were either increased or decreased. In scenario 1, withdrawals from wells located within critical area 2 in the Potomac-Raritan-Magothy aquifer system were reduced by amounts ranging from 0 to 35 percent of withdrawals prior to 1992. Critical area 2 is mainly located in Camden County, and most of Burlington and Gloucester Counties. With the reductions, water levels recovered about 30 feet in the regional cone of depression centered in Camden County in the Upper Potomac-Raritan-Magothy aquifer and by 20 ft in the Lower and Middle Potomac-Raritan-Magothy aquifers. In scenarios 2 to 4, withdrawals projected for 2020 were input to the model. In scenario 2, withdrawal restrictions within the critical areas were imposed in the Potomac-Raritan-Magothy aquifer system, the Englishtown aquifer system, and the Wenonah-Mount Laurel aquifer, but withdrawals were increased outside the critical areas to the projected 2020 demand. With withdrawals restrictions in critical areas, water levels recovered about 20 feet at the center of the regional cone of depression in the Upper Potomac-Raritan Magothy aquifer. Water levels recovered by about 20 feet at the center of a regional cone of depression in the Englishtown aquifer system in Ocean County, and by about 20 feet in the Wenonah-Mount Laurel aquifer in the same area. In scenario 3, withdrawals were increased to the projected 2020 demand inside and outside the critical areas. As a result, water levels declined as much as 20 feet at the center of a regional cone of depression in the Englishtown aquifer system in Ocean County, and as much as 10 feet in the Wenonah-Mounty Laurel aquifer near this area. The Englishtown aquifer system and the Wenonah-Mount Laurel aquifer are particularly sensitive to increases and decreases in withdrawals because in certain areas the transmissivities of these aquifers are lower than the transmissivities of other confined aquifers of the New Jersey Coastal Plain, and because these aquifers are hydraulically connected. Simulated water levels declined by as much as 10 ft at the center of the regional cone of depression in Atlantic County. In scenario 4, withdrawal amounts were equal to that in scenario 2, except an additional 13.2 million gallons per day was withdrawn from hypothetical wells located outside the critical areas in the Upper Potomac-Raritan-Magothy aquifer, Englishtown aquifer system, and the Wenonah-Mount Laurel aquifer. The additional withdrawals resulted in increased leakage from overlying aquifers to the Wenonah-Mount Laurel aquifer and subsequently to the Englishtown aquifer system.

Water-Resources Investigations Report↗
USGS2003

Levels at streamflow gaging stations--A CD-ROM based training class

Streamgages record the elevation of the water surface above some reference surface, or datum. This datum is assumed to remain unchanged throughout the life of the gage. However, the elevation of gages and their supporting structures often change over time as a result of earthmovement, floods, ice, and debris. The surveying practice of leveling is used to establish datum for new gage structures and to check for vertical movement of those structures over time. Vertical changes in gage structures can affect stage-discharge relations and, thus, could result in incorrect discharge determinations. Datum checks are used to correct stage-discharge relations and allow the USGS to document gage datum throughout the life of a gage. This training presentation describes methods currently used by the U.S. Geological Survey to run levels at gaging stations. The presentation is narrated, but you control the pace of the presentation. If the computer you are using can view 'MPEG' videos you will be able to take advantage of videos found within the presentation. A test, found at the end of the presentation, can be taken to assess how well you understood the training material. The class is registered as class SW1307 with the National Training Center of the U.S. Geologcial Survey. The presentation was developed using Macromedia Director 8.5(1) and is contained in the file 'WRI-4002.exe', which should auto-launch after the CD-ROM is inserted in the PC. The program only runs on a windows-based personal computer (PC). A sound card and speakers are necessary to take advantage of the narration that accompanies the presentation. Text of narrations is provided, if you are unable to listen to the narrations. Instructions for installing and running the presentation are included in the file ' Intro.html'. The file 'Intro.html' is on the CD-ROM containing the presentation and is available from the presentation's help menu.

Water-Resources Investigations Report↗
USGS2006

Usoi Dam wave overtopping and flood routing in the Bartang and Panj Rivers, Tajikistan

The Usoi dam was created in the winter of 1911 after an enormous seismogenic rock slide completely blocked the valley of the Bartang River in the Pamir Mountains of southeastern Tajikistan. At present the dam impounds 17 million cubic meters of water in Lake Sarez. Flood volume and discharge estimates were made for several landslide generated floods that could overtop the dam. For landslide volumes of 200, 500, and 1,000 million cubic meters, estimated overtopping flood volumes were 2, 22, and 87 million cubic meters of water, respectively. Estimated peak discharge at the dam for these three flood scenarios were 57,000, 490,000, and 1,580,000 cubic meters per second, based on triangular hydrographs of 70-, 90-, and 110-second durations, respectively. Flood-routing simulations were made for the three landslide-induced overtopping floods over a 530-kilometer reach of the Bartang and Panj Rivers below the Usoi dam. A one-dimensional flow model using a Riemann numerical solution technique was selected for the study. A constant 50-meter wide rectangular channel, which represented the mean channel width, was used for the entire reach. A roughness coefficient of 0.038, appropriate for steep mountainous streams, also was used for the entire reach. For the 87 million cubic meter volume overtopping flood scenario, the peak flows were approximately 1,100, 800, and 550 cubic meters per second at locations 50, 100, and 150 kilometers downstream of the dam, respectively. The model was also used to simulate the less likely scenario of an instantaneous dam breach and draining of the total volume of the lake. Simulated peak flows were approximately 64,000, 52,000, 40,000, and 20,000 cubic meters per second at locations 50, 100, 150, and 530 kilometers downstream of the Usoi dam.

Water-Resources Investigations Report↗
USGS2003

A stage-normalized function for the synthesis of stage-discharge relations for the Colorado River in Grand Canyon, Arizona

A method was developed to construct stage-discharge rating curves for the Colorado River in Grand Canyon, Arizona, using two stage-discharge pairs and a stage-normalized rating curve. Stage-discharge rating curves formulated with the stage-normalized curve method are compared to (1) stage-discharge rating curves for six temporary stage gages and two streamflow-gaging stations developed by combining stage records with modeled unsteady flow; (2) stage-discharge rating curves developed from stage records and discharge measurements at three streamflow-gaging stations; and (3) stages surveyed at known discharges at the Northern Arizona Sand Bar Studies sites. The stage-normalized curve method shows good agreement with field data when the discharges used in the construction of the rating curves are at least 200 cubic meters per second apart. Predictions of stage using the stage-normalized curve method are also compared to predictions of stage from a steady-flow model.

Arizona↗
USGS2003

Measurement of sedimentary interbed hydraulic properties and their hydrologic influence near the Idaho Nuclear Technology and Engineering Center at the Idaho National Engineering and Environmental Laboratory

Disposal of wastewater to unlined infiltration ponds near the Idaho Nuclear Technology and Engineering Center (INTEC), formerly known as the Idaho Chemical Processing Plant, at the Idaho National Engineering and Environmental Laboratory (INEEL) has resulted in the formation of perched water bodies in the unsaturated zone (Cecil and others, 1991). The unsaturated zone at INEEL comprises numerous basalt flows interbedded with thinner layers of coarse- to fine-grained sediments and perched ground-water zones exist at various depths associated with massive basalts, basalt-flow contacts, sedimentary interbeds, and sediment-basalt contacts. Perched ground water is believed to result from large infiltration events such as seasonal flow in the Big Lost River and wastewater discharge to infiltration ponds. Evidence from a large-scale tracer experiment conducted in 1999 near the Radioactive Waste Management Complex (RWMC), approximately 13 km from the INTEC, indicates that rapid lateral flow of perched water in the unsaturated zone may be an important factor in contaminant transport at the INEEL (Nimmo and others, 2002b). Because sedimentary interbeds, and possibly baked-zone alterations at sediment-basalt contacts (Cecil and other, 1991) play an important role in the generation of perched water it is important to assess the hydraulic properties of these units.

Idaho↗
USGS2003

Availability and distribution of base flow in lower Honokohau Stream, Island of Maui

Honokohau Stream is one of the few perennial streams in the Lahaina District of West Maui. Current Honokohau water-use practices often lead to conflicts among water users, which are most evident during periods of base flow. To better manage the resource, data are needed that describe the availability and distribution of base flow in lower Honokohau Stream and how base flow is affected by streamflow diversion and return-flow practices. Flow-duration discharges for percentiles ranging from 50 to 95 percent were estimated at 13 locations on lower Honokohau Stream using data from a variety of sources. These sources included (1) available U.S. Geological Survey discharge data, (2) published summaries of Maui Land & Pineapple Company, Inc. diversion and water development-tunnel data, (3) seepage run and low-flow partial-record discharge measurements made for this study, and (4) current (2003) water diversion and return-flow practices. These flow-duration estimates provide a detailed characterization of the distribution and availability of base flow in lower Honokohau Stream. Estimates of base-flow statistics indicate the significant effect of Honokohau Ditch diversions on flow in the stream. Eighty-six percent of the total flow upstream from the ditch is diverted from the stream. Immediately downstream from the diversion dam there is no flow in the stream 91.2 percent of the time, except for minor leakage through the dam. Flow releases at the Taro Gate, from Honokohau Ditch back into the stream, are inconsistent and were found to be less than the target release of 1.55 cubic feet per second on 9 of the 10 days on which measurements were made. Previous estimates of base-flow availability downstream from the Taro Gate release range from 2.32 to 4.6 cubic feet per second (1.5 to 3.0 million gallons per day). At the two principal sites where water is currently being diverted for agricultural use in the valley (MacDonald's and Chun's Dams), base flows of 2.32 cubic feet per second (1.5 million gallons per day) are available more than 95 percent of the time at MacDonald's Dam and 80 percent of the time at Chun's Dam. Base flows of 4.6 cubic feet per second (3.0 million gallons per day) are available 65 and 56 percent of the time, respectively. A base-flow water-accounting model was developed to estimate how flow-duration discharges for 13 sites on Honokohau Stream would change in response to a variety of flow release and diversion practices. A sample application of the model indicates that there is a 1 to 1 relation between changes in flow release rates at the Taro Gate and base flow upstream from MacDonald's Dam. At Chun's Dam the relation between Taro Gate releases and base flow varies with flow-duration percentiles. At the 95th and 60th percentiles, differences in base flow at Chun's Dam would equal about 50 and 90 percent of the change at the Taro Gate.

Hawaii↗
USGS2003

Organic carbon trends, loads, and yields to the Sacramento-San Joaquin Delta, California, water years 1980 to 2000

Organic carbon, nutrient, and suspended sediment concentration data were analyzed for the Sacramento and San Joaquin River Basins for the period 1980-2000. The data were retrieved from three sources: the U.S. Geological Survey's National Water Information System, the U.S. Environmental Protection Agency's Storage and Retrieval System, and the California Interagency Ecological Program's relational database. Twenty sites were selected, all of which had complete records of daily streamflow data. These data met the minimal requirements of the statistical programs used to estimate trends, loads, and yields. The seasonal Kendall program was used to estimate trends in organic carbon, nutrient, and suspended sediment. At all 20 sites, analyses showed that in the 145 analyses for the seven constituents, 95 percent of the analyses had no significant trend. Dissolved organic carbon (DOC) concentrations were significant only for four sites: the American River at Sacramento, the Sacramento River sites near Freeport, Orestimba Creek at River Roads near Crows Landing, and the San Joaquin River near Vernalis. Loads were calculated using two programs, ESTIMATOR and LOADEST2. The 1998 water year was selected to describe loads in the Sacramento River Basin. Organic carbon, nutrient, and suspended sediment loads at the Sacramento River sites near Freeport included transported loads from two main upstream sites: the Sacramento River at Verona and the American River at Sacramento. Loads in the Sacramento River Basin were affected by the amount of water diverted to the Yolo Bypass (the amount varies annually, depending on the precipitation and streamflow). Loads at the Sacramento River sites near Freeport were analyzed for two hydrologic seasons: the irrigation season (April to September) and the nonirrigation season (October to March). DOC loads are lower during the irrigation season then they are during the nonirrigation season. During the irrigation season, water with low concentrations of DOC is released from reservoirs and used for irrigation. On the other hand, during the nonirrigation season, streamflow results from surface water runoff and has higher concentrations of organic carbon, nutrients, and suspended sediment. The 1986 and 1987 water years were selected to describe loads in the San Joaquin River Basin. Organic carbon, nutrient, and suspended sediment loads in the San Joaquin River near Vernalis included transported loads from upstream sites, such as the Mud and Salt Sloughs, the Merced River at River Roads Bridge near Newman, the Tuolumne River at Modesto, and the Stanislaus River at Ripon. Loads at the San Joaquin River near Vernalis also were analyzed for the two seasons. The DOC load for the San Joaquin River at Vernalis is slightly higher during the irrigation season. Yields were calculated in an attempt to rank the subbasins in the Sacramento and San Joaquin River Basins. Five sites delivered streamflow from agricultural and urban sources that had relatively high yields of organic carbon: Sacramento Slough near Knights Landing, Arcade Creek near Del Paso Heights, Salt Slough, Mud Slough, and Colusa Basin Drain at Road 99E near Knights Landing.

California↗
USGS2003

Methods for Estimating Peak Discharges and Unit Hydrographs for Streams in the City of Charlotte and Mecklenburg County, North Carolina

Procedures for estimating peak discharges and unit hydrographs were developed for streams in the city of Charlotte and Mecklenburg County in response to a need for better techniques for characterizing the flow of streams. The procedures presented in this report provide the means for estimating unit hydrographs as part of the process used in watershed modeling and(or) design of stormwater-management structures. The procedures include three statistical relations for use in estimating storm peak discharge, unit-hydrograph peak discharge, and unit-hydrograph lag time. A final component of the procedures is the development of a dimensionless unit hydrograph developed from streamflow and rainfall data collected during the 1995-2000 water years at 25 streamgaging stations and up to 60 raingages in the city and county. The statistical relation to estimate the storm peak discharge is based on analyses of observed peak discharges regressed against rainfall and basin characteristics using a database of 412 observations from 61 storm events among the 25 gaging stations. The rainfall characteristics included basin-average rainfall amounts as well as estimates of the maximum and minimum storm rainfall in the basin. The basin characteristics consisted of land-use information and other physical basin characteristics, such as drainage area, channel length, channel slope, percentage of impervious area, and percentage of the basin served by detention. The analyses resulted in a relation that can be used for estimating storm peak discharge based on drainage area, basin-average rainfall, and impervious area. Average unit hydrographs were developed for 24 of 25 streamgaging stations, using from three to nine storms at each site. The average unit hydrograph for each station was converted into four classes of unit hydrographs with durations corresponding to one-fourth, one-third, one-half, and three-fourths of the station-average lag time. For 23 sites, the lag-time-duration hydrographs were then translated into dimensionless unit hydrographs by dividing time ordinates by the lag time and discharge ordinates by peak discharge. For each lag-time-duration class, the dimensionless unit hydrographs for the sites were combined to create an average dimensionless unit hydrograph. The four average dimensionless unit hydrographs were later tested (with estimates of unit-hydrograph peak discharges and lag times) for selection of an overall dimensionless unit hydrograph to be used at ungaged sites in the study area. The two sites where the procedures did not produce unit hydrographs that could be included in the development of the overall dimensionless unit hydrograph had the smallest drainage areas among the sites used in the investigation. The statistical relations for estimating unit-hydrograph peak discharge and lag time were developed by regressing the dependent variables against explanatory variables that describe the basin characteristics. The statistical analyses resulted in a relation for use in estimating a unit-hydrograph peak discharge based on the drainage area. The estimation of the unit-hydrograph lag time is based on the drainage area and percentage of land use in the basin classified as 'woods/brush.' Both relations have coefficients of determination (R2 values) of 0.9 or better. The three components for estimating a unit hydrograph are the dimensionless unit hydrograph and two statistical relations for estimating the unit-hydrograph peak discharge and lag time. These components were applied by using each of the four lag-time-duration average dimensionless unit hydrographs to determine which would be selected as the final overall dimensionless unit hydrograph for streams in the city of Charlotte and Mecklenburg County. Comparisons of the simulated and observed hydrographs were based on the following: (1) hydrograph width at 50 percent of the peak discharge, (2) hydrograph width at 75 percent of the peak discharge, (3) peak discharge

North Carolina↗
USGS2004

Quality of Water from Shallow Wells in Urban Residential and Light Commercial Areas in Lafayette Parish, Louisiana, 2001 through 2002

In 2001-02, the U.S. Geological Survey installed and sampled 28 shallow wells in urban residential and light commercial areas in Lafayette Parish, Louisiana, for a land-use study in the Acadian-Pontchartrain Study Unit of the National Water-Quality Assessment (NAWQA) Program. The wells were installed in the Chicot aquifer system, the primary source of water for irrigation and public-water supplies in southwestern Louisiana. The purpose of this report is to describe the quality of water from the 28 shallow wells and to relate that water quality to natural factors and to human activities. Ground-water samples were analyzed for general ground-water properties and about 240 water-quality contituents, including dissolved solids, major inorganic ions, trace elements, nutrients, dissolved organic carbon (DOC), radon, chlorofluorocarbons, selected stable isotopes, pesticides, pesticide degradation products, and volatile organic compounds (VOC's).

Water-Resources Investigations Report↗