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USGS2007

Climate variation at Flagstaff, Arizona - 1950 to 2007

Much scientific research demonstrates the existence of recent climate variation, particularly global warming. Climate prediction models forecast that climate will change; it will become warmer, droughts will increase in number and severity, and extreme climate events will recur often—desiccating aridity, extremely wet, unusually warm, or even frigid at times. However, the global models apply to average conditions in large grids approximately 150 miles on an edge (Thorpe, 2005), and how or whether specific areas within a grid are affected is unclear. Flagstaff's climate is mentioned in the context of global change, but information is lacking on the amount and trend of changes in precipitation, snowfall, and temperature. The purpose of this report is to understand what may be happening to Flagstaff's climate by reviewing local climate history. Flagstaff is in north-central Arizona south of San Francisco Mountain, which reaches 12,633 feet, the highest in Arizona (fig. 1). At 6,900 feet, surrounded by ponderosa pine forest, Flagstaff enjoys a four-season climate; winter-daytime temperatures are cool, averaging 45 degrees (Fahrenheit). Summer-daytime temperatures are comfortable, averaging 80 degrees, which is pleasant compared with nearby low-elevation deserts. Flagstaff's precipitation averages 22-inches per year with a range of 9 to 39 inches. Snowfall occurs each season, averaging 97 inches annually. This report, written for the non-technical reader, interprets climate variation at Flagstaff as observed at the National Weather Service (NWS) station at Pulliam Field (or Airport), a first-order weather station staffed by meteorologists (Staudenmaier and others, 2007). The station is on a flat-topped ridge surrounded by forest 5-miles south of Flagstaff at an elevation of 7,003 feet. Data used in this analysis are daily measurements of precipitation (including snowfall) and temperature (maximum and minimum) covering the period from 1950, when the station began operation, through spring 2007. Conversations with Byron Peterson and Michael Staudenmaier of the NWS helped us understand the difficulties of collecting consistent weather data, operation of the station, and Flagstaff's climate. Weather is the daily or even instantaneous state of temperature and precipitation. Climate is the average or accumulation of these parameters over longer time scales such as a week, month, or year. Seasonal (winter, spring, summer, and fall) and annual averages of temperature and accumulated precipitation describe the temporal variation of Flagstaff's climate, which is shown graphically with time series (figs. 2, 4, 6, 8-15). These plots show precipitation or temperature on the ordinate plotted against time on the abscissa, which is a year for annually repeating data or the year of a particular season. The plots reveal changing patterns of precipitation and temperature related to droughts, wet episodes, and rising temperatures.

Arizona↗

USGS1986

Report of the River Master of the Delaware River for the period December 1, 1984 - November 30, 1985

A Decree of the Supreme Court of the United States in 1954 established the position of Delaware River Master. The Decree authorizes diversions of water from the Delaware River basin and requires compensating releases from certain reservoirs of the City of New York to be made under the supervision and direction of the River Master. Reports to the Court, not less frequently than annually, were stipulated. During the 1985 report year, December 1, 1984, to November 30, 1985, precipitation and runoff varied from below average to above average in the Delaware River basin. For the year as a whole, precipitation was near average. Runoff was below average. Operations were under a status of drought warning or drought from January 23, 1984, through the end of the report year. Below-normal precipitation the first half of the year resulted in decreased storage in the reservoirs to record low levels by March 1, 1985. Storage remained at record low levels from March through September. Above-normal precipitation in September and November served to break the drought and increase storage into the normal zone of the operating curves for the reservoirs. Diversions from the Delaware River basin by New York City did not exceed those authorized by the terms of the Amended Decree or those invoked by the several emergency conservation measures throughout the year. There were no diversions from the Delaware River basin by New Jersey during the year. Releases were made as directed by the River Master at rates designed to meet the Montague flow objective on 82 days between June 14 and September 28. Releases were made at conservation rates or at rates designed to relieve thermal stress in the streams downstream from the reservoirs at other times. (See also W89-04133) (USGS)

Open-File Report↗

USGS2017

Synthesis of data from high-frequency nutrient and associated biogeochemical monitoring for the Sacramento–San Joaquin Delta, northern California

Executive Summary This report is the second in a series of three reports that provide information about high-frequency (HF) nutrient and biogeochemical monitoring in the Sacramento–San Joaquin Delta of northern California (Delta). The purpose of this report is to synthesize the data available from a nutrient and water-quality HF (about every 15 minutes) monitoring network operated by the U.S. Geological Survey in the northern Delta. In this report, we describe the network and focus on the purpose of each station. We then present and discuss the available data, at various timescales—first at the monthly, seasonal, and inter-annual timescales, and second, for comparison, at the tidal and event timescales. As expected, we determined that there is substantial variability in nitrate-N concentrations at short timescales within hours, but also significant variability at longer timescales such as months or years. Resolving this variability is made possible by the HF data, with the largest variability caused by storms, tides, and diel biological processes. Given this large temporal variability, calculations of cumulative nutrient fluxes (for example, daily, monthly, or annual loads) is difficult without HF data. For example, in the Cache Slough, calculation of the annual load without the tidal variability resulted in a 30 percent underestimation of the true annual load value. We conclude that HF measurements are important for accurate determination of fluxes and loads in tidal environments, but, more importantly, provide important insights into processes and rates of nutrient cycling. This report, along with the other two reports of this series (Bergamaschi and others, 2017; Kraus, Bergamaschi, and others, 2017), was drafted in cooperation with the Delta Regional Monitoring Program to help scientists, managers, and planners understand how HF data improve our understanding of nutrient sources and sinks, drivers, and effects in the Delta. The first report in the series (Kraus, Bergamaschi, and others, 2017) provides an introduction to the reasons for and fundamental concepts behind using HF monitoring measurements, including a brief summary of nutrient status and trends in the Delta and an extensive literature review showing how and where other research and monitoring programs have used HF monitoring to improve our understanding of nutrient cycling. The report covers the various technologies available for HF nutrient monitoring and presents the different ways HF monitoring instrumentation may be used for fixed station and spatial assessments. Finally, it presents numerous examples of how HF measurements are currently (2017) being used in the Delta to examine how nutrients and nutrient cycling are related to aquatic habitat conditions. The third report in the series (Bergamaschi and others, 2017) provides the background, principles, and considerations for designing an HF nutrient-monitoring network for the Delta to address high-priority, nutrient-management questions. The report starts with discussion of the high‑priority management questions to be addressed, continues through discussion of the questions and considerations that place demands and constraints on network design, discusses the principles applicable to network design, and concludes with the presentation of three example nutrient-monitoring network designs for the Delta, proposed to address high-priority questions identified by the Delta Regional Monitoring Program (Delta Regional Monitoring Program Technical Advisory Committee, 2015).

California↗

USGS2024

Modeling the impacts of Glen Canyon Dam operations on Colorado River resources

At the time of this report, the Bureau of Reclamation (Reclamation) is writing two supplemental Environmental Impact Statements (sEIS ) and a new Environmental Impact Statement (EIS) that will analyze the effects of changing water flow out of Glen Canyon Dam (GCD) (U.S. Department of Interior, 2024). These actions have the potential to affect downstream resources, including threatened and endangered species, in the Grand Canyon. This report covers modeling support provided on the two sEIS by the USGS Grand Canyon Monitoring and Research Center (GCMRC; U.S. Geological Survey, Southwest Biological Science Center). The first sEIS (Interim Guidelines sEIS) modifies Reclamation’s 2007 Colorado River Interim Guidelines for Lower Basin Shortages and Coordinated Operations for Lake Powell and Lake Mead (USBR, 2007) that determines annual water releases from GCD based on inflow to Lake Powell, the power generating requirements of GCD, and relative lake levels of Lake Powell and Lake Mead. Drought conditions have lowered the level of Lake Powell and may require GCD to release less water than was analyzed in the Interim EIS (7-million-acre feet/year). The effect of less water released, as well as lower lake levels and associated water quality concerns, on downstream resources was not analyzed in the 2007 Interim Guidelines EIS. Reclamation requested GCMRC support to provide models predicting the effects to resources of water releases lower than 7M acre feet/year, including models predicting effects to threatened and endangered species for use in a Biological Assessment.

Report↗

USGS1987

Report of the River Master of the Delaware River for the period December 1, 1985, to November 30, 1986

A Decree of the Supreme Court of the United States in 1954 established the position of Delaware River Master. The Decree authorizes diversions of water from the Delaware River Basin (Figure 1) and requires compensating releases from certain reservoirs of the City of New York to be made under the supervision and direction of the River Master. Reports to the Court, not less frequently than annually, were stipulated. During the 1986 report year, December 1, 1985, to November 30, 1986, precipitation and runoff varied from below average to above average in the Delaware River Basin. For the year as a whole, precipitation was 4.3 inches above average. Runoff was near average. Operations were under a status of drought at the beginning of the report year. The drought emergency was terminated on December 18, 1985, by the Delaware River Basin Commission, and operations were returned to normal as prescribed by the Decree for the remainder of the report yr. Storage in the reservoirs increased to capacity during the winter months and all New York City Delaware River Basin reservoirs spilled throughout the year. Diversions from Delaware River Basin by New York City and New Jersey did not exceed those authorized by the terms of the Amended Decree. Releases were made as directed by the River Master at rates designed to meet the Montague flow objective on 69 days during the June to November period. Releases were made at conservation rates or at rates designed to relieve thermal stress in the streams downstream from the reservoirs at other times. The excess release quantity as defined by the Decree was not expended by end of the report year. New York City complied fully with the terms of the Decree and with the directives of the River Master during the year. (See also W89-04133) (USGS)

Open-File Report↗

USGS2011

Colorimetric determination of nitrate plus nitrite in water by enzymatic reduction, automated discrete analyzer methods

This report documents work at the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) to validate enzymatic reduction, colorimetric determinative methods for nitrate + nitrite in filtered water by automated discrete analysis. In these standard- and low-level methods (USGS I-2547-11 and I-2548-11), nitrate is reduced to nitrite with nontoxic, soluble nitrate reductase rather than toxic, granular, copperized cadmium used in the longstanding USGS automated continuous-flow analyzer methods I-2545-90 (NWQL laboratory code 1975) and I-2546-91 (NWQL laboratory code 1979). Colorimetric reagents used to determine resulting nitrite in aforementioned enzymatic- and cadmium-reduction methods are identical. The enzyme used in these discrete analyzer methods, designated AtNaR2 by its manufacturer, is produced by recombinant expression of the nitrate reductase gene from wall cress (Arabidopsis thaliana) in the yeast Pichia pastoris. Unlike other commercially available nitrate reductases we evaluated, AtNaR2 maintains high activity at 37°C and is not inhibited by high-phenolic-content humic acids at reaction temperatures in the range of 20°C to 37°C. These previously unrecognized AtNaR2 characteristics are essential for successful performance of discrete analyzer nitrate + nitrite assays (henceforth, DA-AtNaR2) described here. Method detection levels (or limits; MDL) estimated for standard- and low-level DA-AtNaR2 nitrate + nitrite methods were 0.02 milligrams nitrogen per liter (mg-N/L) and 0.002 mg-N/L, respectively, which are comparable to 2010 NWQL long-term MDLs of the continuous-flow analyzer, cadmium-reduction methods (henceforth, CFA-CdR) they replace. Typically, reagent-water blanks for standard- and low-level DAAtNaR2 nitrate + nitrite methods are one half MDL or less. Nitrate + nitrite concentration differences for between-day replicates were 3 percent or less at or above 5 times the MDL and were as great as 35 percent near the MDL. Typically, nitrate spike recoveries from reagent water, surface water, groundwater, and high-phenolic-content, humic-acid-amended reagent water were 100±20 percent. In addition to operational details and performance benchmarks for these new DA-AtNaR2 nitrate + nitrite assays, this report also provides results of interference studies for common inorganic and organic matrix constituents at 1, 10, and 100 times their median concentrations in surface-water and groundwater samples submitted annually to the NWQL for nitrate + nitrite analyses. Paired t-test and Wilcoxon signed-rank statistical analyses of results determined by CFA-CdR methods and DA-AtNaR2 methods indicate that nitrate concentration differences between population means or sign ranks were either statistically equivalent to zero at the 95 percent confidence level (p ≥ 0.05) or analytically equivalent to zero-that is, when p < 0.05, concentration differences between population means or medians were less than MDLs.

Techniques and Methods↗

USGS2016

Performance evaluation testing of wells in the gradient control system at a federally operated Confined Disposal Facility using single well aquifer tests, East Chicago, Indiana

The U.S. Geological Survey (USGS) performed tests to evaluate the hydrologic connection between the open interval of the well and the surrounding Calumet aquifer in response to fouling of extraction well pumps onsite. Two rounds of air slug testing were performed on seven monitoring wells and step drawdown and subsequent recovery tests on three extraction wells on a U.S. Army Corps of Engineers Confined Disposal Facility (CDF) in East Chicago, Indiana. The wells were tested in 2014 and again in 2015. The extraction and monitoring wells are part of the gradient control system that establishes an inward gradient around the perimeter of the facility. The testing established a set of protocols that site personnel can use to evaluate onsite well integrity and develop a maintenance procedure to evaluate future well performance. The results of the slug test analysis data indicate that the hydraulic connection of the well screen to the surrounding aquifer material in monitoring wells on the CDF and the reliability of hydraulic conductivity estimates of the surrounding geologic media could be increased by implementing well development maintenance. Repeated air slug tests showed increasing hydraulic conductivity until, in the case of the monitoring wells located outside of the groundwater cutoff wall (MW–4B, MW–11B, MW–14B), the difference in hydraulic conductivity from test to test decreased, indicating the results were approaching the optimal hydraulic connection between the aquifer and the well screen. Hydraulic conductivity values derived from successive tests in monitoring well D40, approximately 0.25 mile south of the CDF, were substantially higher than those derived from wells on the CDF property. Also, values did not vary from test to test like those measured in monitoring wells located on the CDF property, which indicated that a process may be affecting the connectivity of the wells on the CDF property to the Calumet aquifer. Derived hydraulic conductivity values from the initial air slug test during the 2015 testing period for MW–11A and MW–14A are an order of magnitude less than those derived from the final test during the 2014 testing period indicating the development of a low conductivity skin between the final test of the 2014 testing period and the beginning of the 2015 testing period that created a decrease in the connection of the monitoring well screen to the surrounding aquifer material. Repeated step drawdown and recovery testing of the extraction wells tested during this study provided results that indicate a slight increase in the development of a skin and a decrease in the connectivity of the extraction wells with the Calumet aquifer. Hydraulic conductivity values obtained from the test results were relatively similar in EW–4B and EW–14A but were substantially lower for EW–11C. This difference may be due to the presence of finer grained silt deposits in the area surrounding well nest 11. Skin factors calculated during the step drawdown and recovery analysis were lowest in EW–11C and relatively similar in EW–4B and EW–14A. Calculated skin factors increased slightly in the analysis of data collected in 2015 from that collected in 2014. Comparisons of the specific-capacity values calculated from well development data collected following extraction well installation to those calculated during the single well aquifer tests at EW–4B, EW–14A and EW–11C indicate that the productivity of extraction wells on the CDF property has diminished since 2008. Values calculated for monitoring wells MW–4A, MW–11A, and MW–14A were used to evaluate the decrease in air slug derived hydraulic conductivity for monitoring wells within the groundwater cutoff wall between testing in 2014 and 2015. Results from testing by this study indicate that implementation of an air slug testing regimen of the monitoring wells that control the gradient control system at the CDF throughout the course of a year may help sustain the connectivity between the monitoring wells and the surrounding aquifer and provide data to evaluate the need for different types of well development approaches to address chemical or biological fouling issues. Repeated step drawdown and recovery testing of the extraction wells tested during this study provided results that indicate a slight increase in the development of a skin and a decrease in the connectivity of the extraction wells with the Calumet aquifer. Implementation of a specific capacity testing regimen can provide data to record and track well condition through time for individual extraction wells. Results from aquifer testing by this study indicate that specific capacity test results, when paired with recovery testing, provide useful data to measure the development of any low conductivity wellbore skin through the skin factors derived for the individual extraction wells. An initial annual schedule of specific capacity and recovery tests would provide sufficient data to identify substantial short-term changes in the operating condition of the extraction wells.

Indiana↗

USGS2001

Water quality in the upper Shoal Creek basin, southwestern Missouri, 1999-2000

Results of a water-quality investigation of the upper Shoal Creek Basin in southwestern Missouri indicate that concentrations of total nitrite plus nitrate as nitrogen (NO2t+NO3t) in water samples from Shoal Creek were unusually large [mean of 2.90 mg/L (milligrams per liter), n (sample size)=60] compared to other Missouri streams (mean of 1.02 mg/L, n=1,340). A comparison of instantaneous base-flow loads of NO2t+NO3t indicates that at base-flow conditions, most NO2t+NO3t discharged by Shoal Creek is from nonpoint sources. Nearly all the base-flow instantaneous load of total phosphorus as P (Pt) discharged by Shoal Creek can be attributed to effluent from a municipal wastewater treatment plant. Samples collected from a single runoff event indicate that substantial quantities of Pt can be transported during runoff events compared to base-flow transport. Only minor quantities of NO2t+NO3t are transported during runoff events compared to base-flow transport. Fecal coliform bacteria densities at several locations exceed the Missouri Department of Natural Resources (MDNR) standard of 200 col/100 mL (colonies per 100 milliliters) for whole-body contact recreation. During 13 months of monitoring at 13 stream sites, fecal coliform densities (median of 277 and 400 col/100 mL) at two sites (sites 2 and 3) on Shoal Creek exceeded the MDNR standard at base-flow conditions. The maximum fecal coliform density of 120,000 col/100 mL was detected at site 3 (MDNR monitoring site) during a runoff event in April 1999 at a peak discharge of 1,150 ft3/s (cubic feet per second). Fecal coliform densities also exceeded the MDNR standard in three tributaries with the largest densities (median of 580 col/100 mL) detected in Pogue Creek. Results of ribopattern analyses indicate that most Escherichia coli (E. coli) bacteria in water samples from the study area probably are from nonhuman sources. The study area contains about 25,000 cattle, and has an estimated annual production of 33 million broilers and 300,000 turkeys. Probable nonhuman sources included turkeys, horses, chickens, and cattle; however, wildlife sources such as deer, raccoon, muskrat, and opossum were not evaluated. Human waste was an important source of E. coli in water samples collected at the MDNR monitoring site (site 3) on Shoal Creek and at two tributary sites (Joyce Creek and Woodward Creek). In general, the detection of human ribopatterns was consistent with the detection of organic compounds commonly associated with human wastewater such as caffeine, triclosan, or phenol, and the fecal indicators cholesterol and 3B-coprostanol. Ribopattern analysis indicate that horses were an important source of E. coli in Woodward Creek, which was consistent with horses being pastured immediately upstream from the sampling site on this creek. Pogue Creek contains a large density of turkey barns and five of eight E. coli isolates from one sample from Pogue Creek were matched to turkeys. Water samples from Pogue Creek generally did not contain detectable concentrations of human wastewater compounds, but one sample did contain detectable quantities of the antibiotics tylosin and lincomycin (widely used in the animal industry), and sulfamethoxazole (human use only). Although promising, the ability of ribopattern analyses to positively identify the source of a particular isolate is uncertain because of the small sample size, possible differences between animal source patterns in the study area and database used, lack of native wildlife source patterns, and variation in results depending on the number of possible animal host considered. Results of this study indicate that a trend of increasing fecal coliform densities with increasing time detected by the MDNR is, in part, caused by trends in annual precipitation and stream discharge, and not necessarily changes in land use or densities of animal operations. A multiple linear regression (MLR) model using specific conductance and wate

Water-Resources Investigations Report↗

USGS2024

Flood of October 31 to November 3, 2019, in the East Canada Creek, West Canada Creek, and Sacandaga River basins in central New York

Between October 31 and November 3, 2019, historic flooding in localized areas of the Mohawk Valley and southern Adirondack region in central New York State resulted in one fatality and an estimated $33 million in damages. Flooding resulted from high-intensity, hyperlocal rainfall in the region within a 24-hour period between October 31 and November 1, 2019, at the end of a much wetter than average October. In that 24-hour period, rainfall amounts largely ranged from 2 to 5 inches in the most heavily affected parts of the region, but a maximum rainfall amount for the region of 7 inches was recorded in Speculator, New York. This rainfall total for a 24-hour period for this location is estimated to have between a 200- and 500-year recurrence interval. The most severe flooding to result from the rainfall was mainly in the Sacandaga River basin, which is within the upper Hudson River basin, and in the East and West Canada Creek basins, which are within the Mohawk River basin. Streamflow, stage, and reservoir elevation data, collected by the U.S. Geological Survey, are documented in this report. Flooding resulted in new peak streamflow records at five of six U.S. Geological Survey streamgages in the region that have periods of record of at least 20 years, including at three streamgages that have been in operation for about 100 years. At the sixth streamgage, this flooding resulted in the second highest peak streamflow in its 71-year period of record. For all six streamgages, estimates of flood magnitudes for selected annual exceedance probabilities were updated using the peak streamflows from the flooding. Additionally, the annual exceedance probabilities for the six respective peak streamflows were all estimated to be less than 1 percent (greater than a 100-year recurrence interval). At three of those six streamgages, however, previous annual peak streamflows of comparable magnitudes (within 10 percent) have also happened within the past 20 years.

New York↗

USGS1979

Selected coal-related ground-water data, Wasatch Plateau-Book Cliffs area, Utah

The Wasatch Plateau-Book Cliffs%area as used in this report consists of about 8,000 square miles in east-central Utah. The major geographic features included in the area are the Wasatch Plateau, Book Cliffs, San Rafael Swell, Price River basin, and a small part of the Green River basin (pl. 1). The area is defined by approximate drainage-divide boundaries in the Wasatch Plateau and Book Cliffs, by an arbitrary boundary on the south, and by the Utah-Colorado State line on the east. The Wasatch Plateau-Book Cliffs area includes all the operating coal mines in Utah in 1978. Annual coal production in the area is expected to increase from the current (1978) rate of about 8 million tons to as much as 30 million tons within the next 10 years (J. W. Moffitt, U.S. Geological Survey, oral commun., 1978). Ground water is an important source of water supply in the area. As mining increases and mining-related municipalities grow, many sources of ground-water supply may be subjected to increased demands and possibly degradation of chemical quality. Waddell, Vickers, Upton, and Contratto (1978) reported some ground- water data after a reconnaissance of part of the area. The purpose of this report, which was prepared in cooperation with the U.S. Bureau of Land Management, is to present a more detailed compilation of ground-water-related data that were collected and compiled during October 1976 to March 1978. The report is designed to make the data available in an orderly and usable form for local and regional water managers and other users of water data.

Utah↗

USGS1975

Hydrology of the Albemarle-Pamlico region, North Carolina : A preliminary report on the impact of agricultural developments

Extensive agricultural land clearing and drainage operations underway in a 650 square mile part of the Albemarle-Pamlico region--a 1,634 square mile peninsula in North Carolina lying between Albemarle Sound on the North and the Pamlico River on the south--are changing the hydrology of the area. The artificial drainage system being constructed in the region, although it will probably result in only a slight modification of the natural annual evapotranspiration, overland runoff, and ground-water discharge, will likely result in several important problems. First, changes in the water quality of the sounds and estuaries resulting from the rapid runoff of storm waters may prove harmful to the fishery resources. Second, lowering of the water table may cause relatively rapid subsidence of the land surface in an irregular pattern in the extensive areas underlain by thick peat deposits as a result of biochemical oxidation, peat fires, and wind.

North Carolina↗

USGS2010

Low-flow frequency and flow duration of selected South Carolina streams in the Broad River basin through March 2008

In 2008, the U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 23 selected streamgaging stations in the Broad River basin in South Carolina, and includes flow durations of 5-, 10-, 25-, 50-, 75-, 90-, and 95-percent probability of exceedance and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day mean flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. The low-flow statistics were computed from records available through March 31, 2008. In addition, flow duration information is presented for one streamgaging station 021556525, Pacolet River below Lake Blalock near Cowpens, SC, where recurrence interval computations were not appropriate. Of the 23 streamgaging stations for which recurrence interval computations were made, 14 had low-flow statistics that were published in previous U.S. Geological Survey reports. A comparison of the low-flow statistics for the minimum mean flow for a 7-consecutive-day period with a 10-year recurrence interval (7Q10) from this study with the most recently published values indicated that 8 of the 14 streamgaging stations had values that were within plus or minus 25 percent of the previous value. Ten of the 14 streamgaging stations had negative percent differences indicating the low-flow statistic had decreased since the previous study, and 4 streamgaging stations had positive percent differences indicating that the low-flow statistic had increased since the previous study. The low-flow statistics are influenced by length of record, hydrologic regime under which the record was collected, techniques used to do the analysis, and other changes, such as urbanization, diversions, and so on, that may have occurred in the basin.

South Carolina↗

USGS2010

Streamflow, suspended-sediment, and soil-erosion data from Kaulana and Hakioawa watersheds, Kaho'olawe, Hawai'i, 2006 to 2010

Various events over the last two centuries have destroyed the vegetation and caused rapid soil erosion on large areas of the small, arid, windy tropical shield-volcano island of Kaho`olawe, Hawai`i. These activities were largely halted in the 1990s, and efforts have been made to restore the island's vegetation in order to stem erosion. In 2003, the Kaho`olawe Island Reserve Commission (KIRC) began restoration efforts using native vegetation. In 2006 to 2010, the U.S. Geological Survey (USGS), in cooperation with the KIRC, monitored streamflow, fluvial suspended-sediment transport, and erosion rates in the Hakioawa and Kaulana watersheds on northeastern Kaho`olawe to provide information needed to assess the effectiveness of restoration efforts. This report presents the results from this monitoring. Results.-Hakioawa and Kaulana gulches were dry about 90 percent of the time during the monitoring period; mean annual flow was 0.06 ft3/s at Hakioawa Gulch gage and 0.01 ft3/s at the Kaulana Gulch gage. For the period when the sediment gages on both gulches were operating concurrently (October 2007 to September 2009), sediment discharge was higher from Hakioawa Gulch than from Kaulana Gulch. The annual suspended-sediment loads for the concurrent period averaged 1,880 tons at the Hakioawa Gulch gage and 276 tons at the Kaulana Gulch gage. Of the 77 erosion-monitoring sites in the Hakioawa and Kaulana watersheds, 50 had overall rates of change indicating erosion for the monitoring period, ranging from -1 to -10 mm/yr and averaging -3 mm/yr. Seven sites had rates of change indicating overall deposition, ranging from 1 to 15 mm/yr and averaging 5 mm/yr. Twenty had rates of change below detection (less than ?1 mm/yr). The average rate of change for the 26 sites in areas that have undergone restoration by the KIRC was below the detection limit of the erosion-monitoring method. In comparison, the 51 sites in nonrestoration areas averaged -2 mm/y. Both of these averages, however, include sites that showed overall erosion as well as sites that showed overall deposition. The average rate of change was -1 mm/yr for both the 32 sites on rills and the 42 sites on interfluves; both categories include sites that showed deposition as well as sites that showed erosion. All three sites on hummocks showed overall erosion, with an average rate of -8 mm/yr. Both the Hakioawa and Kaulana watersheds showed an average rate of change of -1 mm/yr, and both included sites that showed erosion and sites that showed deposition. For sites with negative rates of change indicating erosion, the average rate of change during the monitoring period was -2 mm/yr in restoration areas and -3 mm/yr in nonrestoration areas. For sites with positive rates of change indicating deposition, the average rate of change was 5 mm/yr in restoration areas and 6 mm/yr in nonrestoration sites. The average rate of change for rills was 1 mm/yr in restoration areas and -2 mm/yr in nonrestoration sites. The average rate of change for interfluves was below detection in restoration areas and -1 mm/yr in nonrestoration areas. Potential Use and Limitation of Data.-Additional statistical comparisons of various subsets of erosion data can be used to assess the effectiveness of restoration efforts or how existing landforms, vegetation, climate, and other physical basin characteristics affect erosion and fluvial sediment transport in the watersheds. Further investigation to identify what factors cause the Kaulana watershed to have much lower runoff and sediment loads than the Hakioawa watershed may yield valuable information for developing and modifying restoration strategies. Continued monitoring of streamflow, sediment transport, and erosion is key to assessing the long-term effectiveness of restoration and can provide insight to the island's recovery since the eradication of feral goats and cessation of use as a military bombing range; the results of this study provide the

Hawaii↗

USGS1995

Status of ground-water resources at U.S. Navy Support Facility, Diego Garcia; summary of hydrologic and climatic data through September 1993

This report contains hydrologic and climatic data that describe the status of ground-water resources at U.S. Navy Support Facility, Diego Garcia. Data are presented through September 1993, one month into the annual wet season. At the end of September 1993, the chloride concentration of the composite water supply was 66 milligrams per liter, well below the 250 milligrams per liter secondary drinking water standard established by the U.S. Environmental Protection Agency. Most of the production wells appeared to be operating at levels consistent with past operations. Several wells at Air Operations remain out of service while they are being used to hydraulically divert the nearby fuel spill. Rainfall thus far in 1993 is 8 percent below the mean annual rainfall of 106 inches. This follows a year when rainfall was 12 percent below the mean annual rainfall. Withdrawal has averaged 856,000 gallons per day during 1993, a decrease from the 1992 average of 936,000 gallons per day. The chloride concentration of pumped water rose during the current quarter (July through September 1993) in most areas, coincident with the annual dry season (March through August). This continues a general trend of increasing chloride concentration that has persisted for more than a year, beginning in the 1992 dry season. Chloride concentration rose progressively during the current quarter in monitoring wells at Cantonment and Air Operations. Chloride concentrations in the deeper monitoring wells have generally been increasing since 1992. A fuel spill at Air Operations caused the shutdown of ten wells in May 1991. Four of the wells have resumed pumping to the water supply, but water from the remaining six wells is being used to hydraulically contain and divert fuel migration.

Open-File Report↗

USGS1980

Cost effective stream-gaging strategies for the Lower Colorado River basin; the Blythe field office operations

This report describes the theoretical developments and illustrates the applications of techniques that recently have been assembled to analyze the cost-effectiveness of federally funded stream-gaging activities in support of the Colorado River compact and subsequent adjudications. The cost effectiveness of 19 stream gages in terms of minimizing the sum of the variances of the errors of estimation of annual mean discharge is explored by means of a sequential-search optimization scheme. The search is conducted over a set of decision variables that describes the number of times that each gaging route is traveled in a year. A gage route is defined as the most expeditious circuit that is made from a field office to visit one or more stream gages and return to the office. The error variance is defined as a function of the frequency of visits to a gage by using optimal estimation theory. Currently a minimum of 12 visits per year is made to any gage. By changing to a six-visit minimum, the same total error variance can be attained for the 19 stations with a budget of 10% less than the current one. Other strategies are also explored. (USGS)

Open-File Report↗

USGS1962

Glacier observations, Glacier National Park, Montana, 1961

This report records the results obtained during the 1961 season in the continuing program of glacier observations in Glacier National Park. The investigations currently in progress relate to the Grinnell and Sperry Glaciers. This program is carried on cooperatively by the Geological Survey, the National Park Service and the Weather Bureau. The program includes the determination of annual changes in the surface elevation of the glaciers by the measurement of profiles, and changes during the summer months by the establishment of and observations at ablation stakes; rapping the glacier termini in selected years to record advance or recession; determination of annual movement by the location of marked rocks; the operation of two storage-precipitation gages in the immediate vicinity of the Grinnell Glacier to record annual precipitation; the operation of two gaging stations, one just below the Grinnell Glacier during the summer months and one Just below the outlet of Grinnell Lake on a year round basis; temperature data near the Grinnell Glacier and temperature and precipitation data at the Sperry Chalet near the Sperry Glacier during the summer months. The results of the work are described in the following sections.

Montana↗

USGS2012

Low-flow frequency and flow duration of selected South Carolina streams in the Saluda, Congaree, and Edisto River basins through March 2009

Part of the mission of the South Carolina Department of Health and Environmental Control and the South Carolina Department of Natural Resources is to protect and preserve South Carolina's water resources. Doing so requires an ongoing understanding of streamflow characteristics of the rivers and streams in South Carolina. A particular need is information concerning the low-flow characteristics of streams, which is especially important for effectively managing the State's water resources during critical flow periods, such as during periods of severe drought like South Carolina has experienced in the last decade or so. The U.S. Geological Survey, in cooperation with the South Carolina Department of Health and Environmental Control, initiated a study in 2008 to update low-flow statistics at continuous-record streamgaging stations operated by the U.S. Geological Survey in South Carolina. This report presents the low-flow statistics for 25 selected streamgaging stations in the Saluda, Congaree, and Edisto River basins in South Carolina, and includes flow durations for the 5-, 10-, 25-, 50-,75-, 90-, and 95-percent exceedances and the annual minimum 1-, 3-, 7-, 14-, 30-, 60-, and 90-day average flows with recurrence intervals of 2, 5, 10, 20, 30, and 50 years, depending on the length of record available at the streamgaging station. The low-flow statistics were computed from records available through March 31, 2009. Of the 25 streamgaging stations for which recurrence interval computations were made, 20 were compared to low-flow statistics that were published in previous U.S. Geological Survey reports. A comparison of the low-flow statistics for the annual minimum 7-day average streamflow with a 10-year recurrence interval (7Q10) from this study with the most recently published values indicates that 18 of the 20 streamgaging stations have values lower than the previous published values. The low-flow statistics are influenced by length of record, hydrologic regime under which the record was collected, analytical techniques used, and other changes, such as urbanization, diversions, droughts, and so on, that may have occurred in the basin.

South Carolina↗

USGS2011

Groundwater recharge in Wisconsin— Annual estimates for 1970–99 using streamflow data

The groundwater component of streamflow is important because it is indicative of the sustained flow of a stream during dry periods, is often of better quality, and has a smaller range of temperatures, than surface contributions to streamflow. All three of these characteristics are important to the health of aquatic life in a stream. If recharge to the aquifers is to be preserved or enhanced, it is important to understand the present partitioning of total streamflow into base flow and stormflow. Additionally, an estimate of groundwater recharge is important for understanding the flows within a groundwater system-information important for water availability/sustainability or other assessments. The U.S. Geological Survey operates numerous continuous-record streamflow-gaging stations (Hirsch and Norris, 2001), which can be used to provide estimates of average annual base flow. In addition to these continuous record sites, Gebert and others (2007) showed that having a few streamflow measurements in a basin can appreciably reduce the error in a base-flow estimate for that basin. Therefore, in addition to the continuous-record gaging stations, a substantial number of low-flow partial-record sites (6 to 15 discharge measurements) and miscellaneous-measurement sites (1 to 3 discharge measurements) that were operated during 1964-90 throughout the State were included in this work to provide additional insight into spatial distribution of annual base flow and, in turn, groundwater recharge.

Wisconsin↗