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At least 955 records · Page 53Linked to original sources
USGS2008

Dissolved-solids transport in surface water of the Muddy Creek Basin, Utah

Muddy Creek is located in the southeastern part of central Utah and is a tributary of the Dirty Devil River, which, in turn, is a tributary of the Colorado River. Dissolved solids transported from the Muddy Creek Basin may be stored in the lower Dirty Devil River Basin, but are eventually discharged to the Colorado River and impact downstream water users. This study used selected dissolved-solids measurements made by various local, State, and Federal agencies from the 1970s through 2006, and additional dissolved-solids data that were collected by the U.S. Geological Survey during April 2004 through November 2006, to compute dissolved-solids loads, determine the distribution of dissolved-solids concentrations, and identify trends in dissolved-solids concentration in surface water of the Muddy Creek Basin. The dissolved-solids concentration values measured in water samples collected from Muddy Creek during April 2004 through October 2006 ranged from 385 milligrams per liter (mg/L) to 5,950 mg/L. The highest dissolved-solids concentration values measured in the study area were in water samples collected at sites in South Salt Wash (27,000 mg/L) and Salt Wash (4,940 to 6,780 mg/L). The mean annual dissolved-solids load in Muddy Creek for the periods October 1976 to September 1980 and October 2005 to September 2006 was smallest at a site near the headwaters (9,670 tons per year [tons/yr]) and largest at a site at the mouth (68,700 tons/yr). For this period, the mean annual yield of dissolved solids from the Muddy Creek Basin was 44 tons per square mile. During October 2005 to September 2006, direct runoff transported as much as 45 percent of the annual dissolved-solids load at the mouth of Muddy Creek. A storm that occurred during October 5?7, 2006 resulted in a peak streamflow at the mouth of Muddy Creek of 7,150 cubic feet per second (ft3/s) and the transport of an estimated 35,000 tons of dissolved solids, which is about 51 percent of the average annual dissolved-solids load at the mouth of Muddy Creek. A significant downward trend in dissolved-solids concentrations from 1973 to 2006 was determined for Muddy Creek at a site just downstream of that portion of the basin containing agricultural land. Dissolved-solids concentrations decreased about 2.1 percent per year; however, the rate of change was a decrease of 1.8 percent per year when dissolved-solids concentrations were adjusted for flow.

Utah↗
USGS2010

Hydrogeologic framework, groundwater and surface-water systems, land use, pumpage, and water budget of the Chamokane Creek basin, Stevens County, Washington

A study of the water resources of the unconsolidated groundwater system of the Chamokane Creek basin was conducted to determine the hydrogeologic framework, interactions of shallow and deep parts of the groundwater system with each other and the surface-water system, changes in land use and land cover, and water-use estimates. Chamokane Creek basin is a 179 mi2 area that borders and partially overlaps the Spokane Indian Reservation in southern Stevens County in northeastern Washington State. Aquifers within the Chamokane Creek basin are part of a sequence of glaciofluvial and glaciolacustrine sediment that may reach total thicknesses of about 600 ft. In 1979, most of the water rights in the Chamokane Creek basin were adjudicated by the United States District Court requiring regulation in favor of the Spokane Tribe of Indians' senior water right. The Spokane Tribe, the State of Washington, and the United States are concerned about the effects of additional groundwater development within the basin on Chamokane Creek. Information provided by this study will be used to evaluate the effects of potential increases in groundwater withdrawals on groundwater and surface-water resources within the basin. The hydrogeologic framework consists of six hydrogeologic units: The Upper outwash aquifer, the Landslide Unit, the Valley Confining Unit, the Lower Aquifer, the Basalt Unit, and the Bedrock Unit. The Upper outwash aquifer occurs along the valley floors of the study area and consists of sand, gravel, cobbles, boulders, with minor silt and (or) clay interbeds in places. The Lower aquifer is a confined aquifer consisting of sand and gravel that occurs at depth below the Valley confining unit. Median horizontal hydraulic conductivity values for the Upper outwash aquifer, Valley confining unit, Lower aquifer, and Basalt unit were estimated to be 540, 10, 19, and 3.7 ft/d, respectively. Many low-flow stream discharge measurements at sites on Chamokane Creek and its tributaries were at or near zero flow. The most notable exception is where Chamokane Creek is supported by discharge of large springs from the Upper outwash aquifer in the southern part of the basin. Most high-flow measurements indicated gains in streamflow (groundwater discharging to the stream). Large streamflow losses, however, were recorded near the north end of Walkers Prairie where streamflow directly recharges the Upper outwash aquifer. The similarity in seasonal water-level fluctuations in the Upper outwash aquifer and the Lower aquifer indicate that these systems may be fairly well connected. Land use and land cover change analysis indicates that Chamokane Creek basin has been dominated by forests with some pasture and agricultural lands with sparse residential development from the 1980s to present. Loss in forest cover represents the largest change in land cover in the basin between 1987 and 2009. This appears to be mostly due to forestry activities, especially in the northern part of the basin. Since 1987, more than 18,000 acres of evergreen forest have been logged and are at various stages of regrowth. Estimated average annual total groundwater pumpage in the basin increased from 224 million gallons per year (Mgal/yr) in 1980 to 1,330 Mgal/yr in 2007. The largest withdrawals during 2007 were to supply two fish hatcheries, with a combined total annual pumpage of about 1,150 Mgal. Annual groundwater pumpage values from 1980 through 2007 for the study area ranged from 21.1 to 28.9 Mgal/yr for domestic wells and 0.38 to 23.7 Mgal/yr for public supply. An approximate water budget for a typical year in the Chamokane Creek basin indicates that 19.6 in. of precipitation are balanced by 4.7 in. of streamflow discharge from the basin, and 14.9 in. of evapotranspiration.

Washington↗
USGS1985

Hydrologic factors affecting lake-level fluctuations in Big Marine Lake, Washington County, Minnesota

A study by the U.S. Geological Survey from 1981 through 1984, in cooperation with the Carnelian-Marine Watershed District and the Minnesota Department of Natural Resources, investigated the causes of large lake-level fluctuations at Big Marine Lake. Historic records document that Big Marine Lake has changed substantially in surface area during the period 1847 through 1983; the maximum lake-surface area was 2,300 acres in 1847, and the minimum lake-surface area was 890 acres in 1938. A change in lake level of about 11 feet caused these changes in surface area. Serious flooding of lake-shore properties has occurred in recent years because residential development commonly took place during periods of relatively low-lake level during the 1950's and 1960's. Evaporation from the lake was estimated to be approximately equal to incident precipitation on the lake surface on an annual basis. Big Marine Lake does not have a surface-water inlet, and the outlet from the lake is at an elevation well above the stage at which lake-shore property is flooded. Hydrogeologic and geochemical data collected during the study show that (1) fluctuation of water levels at Big Marine Lake is controlled primarily by ground-water discharge to and seepage from the lake, (2) water in the drift aquifer and water in the lake are chemically similar, and (3) changes in the potentiometric surface of the bedrock aquifer have minor effects on changes in lake level. Long-term trends in cumulative departure from mean annual precipitation suggest that recharge to the drift aquifer in the area has been increasing since the 1940's. The increase in precipitation and recharge corresponds to the observed rise in lake level since 1965 when regular lake-level measurements began. Fluctuations in lake level in the future will depend on changes in recharge to the drift and bedrock aquifers, which is directly related to changes in long-term precipitation patterns.

Minnesota↗
USGS1995

Estimation of sediment-discharge reduction for two sites of the Yazoo River basin demonstration erosion control project, north-central Mississippi, 1985-94

Sediment-discharge reduction was estimated at two Demonstration Erosion Control sites in north-central Mississippi for the period 1985 through 1994. Decreasing trends were detected in flow-adjusted sediment discharge at Hotopha Creek near Batesville for the study period. The annual reduction in sediment discharge at this site was about 7 percent (0.68 ton per day per year). Decreasing trends were also detected in flow- adjusted sediment discharge at Otoucalofa Creek Canal near Water Valley for the study period. The annual reduction in sediment discharge at this site was about 11 percent (5.33 tons per day per year). The computations used to estimate sediment-discharge reduction were based on time series of instantaneous sediment discharges for the study period. Non-parametric procedures were used to compute trends in sediment discharge and to quantify reductions over time at the two sites. Parametric procedures were then used to verify the non-parametric results.

Water-Resources Investigations Report↗
USGS1987

Hydrology of area 46, Northern Great Plains and Rocky Mountain coal provinces, North Dakota

This report is one of a series that describes the hydrology of coal provinces nationwide. The Northern Great Plains and Rocky Mountain Coal Provinces are divided into 20 separate reporting areas which are numbered 43 to 62. This report provides general hydrologic information for Area 46 using a brief text with accompanying maps, charts, or graphs. This information may be used to describe the hydrology of the general area of any existing or proposed mine. Some of the more obvious hydrologic problems of coal development that will need to be addressed before development are disruption of aquifers and potential contamination of streams, aquifers, and the atmosphere. Area 46 is in northwestern North Dakota and is composed of parts or all of 14 hydrologic units based on surface-water drainage basins. The area is drained by the Missouri and Souris Rivers. Lignite-bearing rocks of late Paleocene age underlie nearly all of Area 46. The thickest and most continuous lignite beds occur in the Sentinel Butte and Tongue River Members of the Fort Union Formation. Alluvial deposits and a veneer of glacial drift of late Pleistocene age overlie the lignite-bearing rocks. The climate of the area is semiarid. Mean annual precipitation ranges from 13.9 to 17.8 inches. Mean annual temperatures range from 37.7°F at Bowbells to 40.9°F at Williston. Mean monthly temperatures at Williston range from 8.3°F to 70°F. The growing season is about 125 days. A fairly comprehensive data base for streamflow and water quality in streams is available for Area 46. Many of the small-stream monitoring sites have been operated during the last few years to provide a data base before coal development. With the exception of the Missouri River, which is controlled by several dams, both the quantity and quality of water varies greatly in all streams. A ground-water observation network for water levels and water quality has been established through county ground-water resource investigations and other ground-water studies and provides an adequate data base. Three activities within the U.S. Geological Survey identify and provide access to hydrologic data. These are the National Water-Data Exchange (NAWDEX), the National Water-Data Storage and Retrieval System (WATSTORE), and the Office of Water-Data Coordination (OWDC).

Open-File Report↗
USGS2025

Potential for biological effects of per- and polyfluoroalkyl substances in Great Lakes tributaries and associations with land cover and wastewater effluent

Surface water concentrations of per- and polyfluoroalkyl substances (PFAS) and potential for resulting biological effects were estimated in a study using polar organic chemical integrative samplers (POCIS) from 60 tributary sites within 20 watersheds in the Great Lakes Basin in 2018. Sites represented a range of urban to agricultural, forested, and wetland land uses and included a gradient of wastewater treatment effluent from zero to 44% of annual streamflow. Several sites also had airport influence. Twenty-one of 32 targeted PFAS compounds were detected in POCIS samplers, of which, 16 had available POCIS sampling rates, enabling time-weighted water concentration estimates and comparison with available effects data. Estimated water concentrations were compared with published water quality guidelines (available for nine PFAS), effect concentrations reported in primary literature within the ECOTOX Knowledgebase for apical endpoints (10 PFAS) and nonapical endpoints (10 PFAS), and in vitro high-throughput screening data from the U.S. Environmental Protection Agency Toxicity Forecaster (ToxCast; 14 PFAS). Based on a conservative evaluation approach that was also weighted for persistence and limitations in available toxicological information, five individual PFAS, including perfluorooctanesulfonic acid, perfluorohexanesulfonic acid, perfluorobutanesulfonic acid, perfluorooctanoic acid, and perfluorononanoic acid were identified as warranting additional investigation. Possible increased potency of PFAS mixtures over individual chemical effects, estimated by summation of exposure-activity ratios (EARs) for chemicals that influence common ToxCast assays and specified gene targets, indicated that EAR values increased up to 5.6-fold over individual chemicals, with up to 14 chemicals contributing to mixture effect predictions. Potential for biological effects from PFAS, as estimated by summed exposure-activity ratios, were correlated with urban land use and the proportion of streamflow contributed by wastewater effluent.

Great Lakes tributaries↗
USGS1985

Calibration procedure for a daily flow model of small watersheds with snowmelt runoff in the Green River coal region of Colorado

A calibration procedure was developed for the U.S. Geological Survey 's Precipitation-Runoff Modeling System for watersheds in which snowmelt is the major contributor to runoff. The model uses daily values of air temperature and precipitation as input and the output is mean daily discharge. The procedure appears sufficient to calibrate both streamflow volume and the timing of mean daily discharge if other model parameters are reasonably estimated. Model structure and sensitivity analysis suggest that one of the most important parameters is the available water-holding capacity of the soil (SMAX). Changing this parameter through a series of iterations, the calibration procedure minimizes the error between observed and predicted annual discharge. The calibration suggests that the single parameter SMAX may be sufficient for optimizing both the volumes and the timing of runoff, assuming other model parameters are adequately estimated. Additional optimization on parameters sensitive to timing does not appear to improve prediction. This indicates that these parameters were estimated accurately prior to calibration. Further investigation is needed on more watersheds to determine SMAX 's ability to calibrate volume and timing with a constant set of other model parameter values.

Colorado↗
USGS2007

Geologic framework studies of South Carolina's Long Bay from Little River Inlet to Winyah Bay, 1999-2003: Geospatial data release

The northern South Carolina coast is a heavily developed region that supports a thriving tourism industry, large local populations and extensive infrastructure (Figure 1). The economic stability of the region is closely tied to the health of its beaches: primarily in providing support for local tourism and protection from storm events. Despite relatively low long-term shoreline erosion rates, and the implied stability of the beaches, the economic impact of storm events to coastal communities has been costly. For example, Hurricane Hugo made landfall on the central South Carolina coast in 1989. High winds and storm surge inflicted roughly $6 billion in property loss and damages, and Hugo remains the costliest storm event in South Carolina history. Localized erosion, commonly occurring around tidal inlets and erosion "hot spots", has also proved costly. Construction and maintenance of hard structures and beach nourishment, designed to mitigate the effects of erosion, have become annual or multi-annual expenditures. Providing a better understanding of the physical processes controlling coastal erosion and shoreline change will allow for more effective management of coastal resources. In 1999, the U.S. Geological Survey (USGS), in partnership with the South Carolina Sea Grant Consortium (SCSGC), began a study to investigate inner continental shelf and shoreface processes. The objectives of the USGS/SCSGC cooperative program are: 1) to provide a regional synthesis of the shallow geologic framework underlying the shoreface and inner continental shelf, and to define its role in coastal evolution and modern beach behavior; 2) to identify and model the physical processes affecting coastal ocean circulation and sediment transport, and to define their role in shaping the modern shoreline; and 3) to identify sediment sources and transport pathways in order to develop a regional sediment budget. This report contains the geospatial data used to define the geologic framework offshore of the northern South Carolina coast. The digital data presented herein accompany USGS Open-File Reports OFR 2004-1013 and OFR 2005-1345, describing the stratigraphic framework and modern sediment distribution within Long Bay, respectively. Direct on-line links to these publications are available within 'References' on the navigation bar to the left. Additional links to other publications and web sites are also available.

South Carolina↗
USGS2014

Flood inundation maps and water-surface profiles for tropical storm Irene and selected annual exceedance probability floods for Flint Brook and the Third Branch White River in Roxbury, Vermont

Flint Brook, a tributary to the Third Branch White River in Roxbury, Vermont, has a history of flooding the Vermont Fish and Wildlife Department’s Roxbury Fish Culture Station (the hatchery) and surrounding infrastructure. Flooding resulting from tropical storm Irene on August 28–29, 2011, caused widespread destruction in the region, including extensive and costly damages to the State-owned hatchery and the transportation infrastructure in the Town of Roxbury, Vermont. Sections of State Route 12A were washed out, and several bridges and culverts on Oxbow Road, Thurston Hill Road, and the New England Central Railroad in Roxbury were heavily damaged. Record high peak-discharge estimates of 2,140 cubic feet per second (ft 3 /s) and 4,320 ft 3 /s were calculated for Flint Brook at its confluence with the Third Branch White River and for the Third Branch White River at about 350 feet (ft) downstream from the hatchery, respectively. The annual exceedance probabilities (AEPs) of the peak discharges for Flint Brook and the Third Branch White River were less than 0.2 percent (less than a one in 500 chance of occurring in a given year). Hydrologic and hydraulic analyses of Flint Brook and the Third Branch White River were done to investigate flooding at the hatchery in Roxbury and support efforts by the Federal Emergency Management Agency to assist State and local mitigation and reconstruction efforts. During the August 2011 flood, the majority of flow from Flint Brook (97 percent or 2,070 ft 3 /s) diverged from its primary watercourse due to a retaining wall failure immediately upstream of Oxbow Road and inundated the hatchery. Although a minor amount of flow from the Third Branch White River could have overtopped State Route 12A and spilled into the hatchery, the Third Branch White River did not cause flood damages or exacerbate flooding at the hatchery during the August 2011 flood. The Third Branch White River which flows adjacent to the hatchery does not flood the hatchery for the 10-, 2-, 1, or 0.2-percent annual exceedance probabilities. The simulated water-surface elevations for August 2011 flood equal the elevations of State Route 12A about 500 ft downstream of Thurston Hill Road adjacent to the troughs between the rearing ponds. Four flood mitigation alternatives being considered by the Vermont Agency of Transportation to improve the hydraulic performance of Flint Brook and reduce the risk of flooding at the hatchery include: (A) no changes to the infrastructure or existing alignment of Flint Brook (existing conditions [2014]), (B) structural changes to the bridges and the existing retaining wall along Flint Brook, (C) realignment of Flint Brook to flow along the south side of Oxbow Road to accommodate larger stream discharges, and (D) a diversion channel for flows greater than 1-percent annual exceedance probability. Although the 10-, 2-, and 1-percent AEP floods do not flood the hatchery under alternative A (no changes to the infrastructure), the 0.2-percent AEP flow still poses a flooding threat to the hatchery because flow will continue to overtop the existing retaining wall and flood the hatchery. Under the other mitigation alternatives (B, C, and D) that include some variation of structural changes to bridges, a retaining wall, and (or) channel, the peak discharges for the 10-, 2-, 1-, and 0.2-percent annual exceedance probabilities do not flood the hatchery. Water-surface profiles and flood inundation maps of the August 2011 flood and the 10-, 2-, 1-, and 0.2-percent AEPs for four mitigation alternatives were developed for Flint Brook and the Third Branch White River in the vicinity of the hatchery and can be used by the Federal, State, and local agencies to better understand the potential for future flooding at the hatchery.

Vermont↗
USGS1988

Sediment inflow, outflow and deposition for Lakes Marion and Moultrie, South Carolina, October 1983 - March 1985

In 1941 a Coastal Plain reach of the Santee River was impounded to form Lake Marion and diverted into a diked-off part of the Cooper River basin to form Lake Moultrie. Rates of sediment inflow and outflow of the lakes were determined by the U.S. Geological Survey for the periods July 1966 - June 1968 and October 1983 - March 1985. Total sediment discharge was estimated for two inflow stations and continuous streamflow monitors and automatic suspended-sediment samplers were used for computation of suspended-sediment discharge. Bedload discharge was computed by the modified Einstein procedure. Suspended-sediment discharge was monitored at three outflow stations, with the suspended-sediment concentration measured on a weekly basis. During the 1983-1985 study, mean annual suspended-sediment inflow to Lakes Marion and Moultrie was estimated to be 722,000 tons, and the outflow was estimated at 175,000 tons, for a trap efficiency of 76% and a deposition rate of about 547,000 tons/year. This is about 33% less than the deposition rate determined during the 1966-68 study. The deposition rate for suspended and bedload sediment during the 1983 - 1985 study was about 650,000 tons/year. (USGS)

South Carolina↗
USGS1999

Precipitation-runoff, suspended-sediment, and flood-frequency characteristics for urbanized areas of Elmendorf Air Force Base, Alaska

The developed part of Elmendorf Air Force Base near Anchorage, Alaska, consists of two basins with drainage areas of 4.0 and 0.64 square miles, respectively. Runoff and suspended-sediment data were collected from August 1996 to March 1998 to gain a basic understanding of the surface-water hydrology of these areas and to estimate flood-frequency characteristics. Runoff from the larger basin averaged 6 percent of rainfall, whereas runoff from the smaller basin averaged 13 percent of rainfall. During rainfall periods, the suspended-sediment load transported from the larger watershed ranged from 179 to 21,000 pounds and that from the smaller watershed ranged from 23 to 18,200 pounds. On a yield basis, suspended sediment from the larger watershed was 78 pounds per inch of runoff and from the smaller basin was 100 pounds per inch of runoff. Suspended-sediment loads and yields were generally lower during snowmelt periods than during rainfall periods. At each outfall of the two watersheds, water flows into steep natural channels. Suspended-sediment loads measured approximately 1,000 feet downstream from the outfalls during rainfall periods ranged from 8,450 to 530,000 pounds. On a yield basis, suspended sediment averaged 705 pounds per inch of runoff, more than three times as much as the combined sediment yield from the two watersheds. The increase in suspended sediment is most likely due to natural erosion of the streambanks. Streamflow data, collected in 1996 and 1997, were used to calibrate and verify a U.S. Geological Survey computer model?the Distributed Routing Rainfall Runoff Model-Version II (DR3M-II). The model was then used to simulate annual peak discharges and runoff volumes for 1981 to 1995 using historical rainfall records. Because the model indicated that surcharging (or ponding) would occur, no flood-frequency analysis was done for peak discharges. A flood-frequency analysis of flood volumes indicated that a 10-year flood would result in 0.39 inch of runoff (averaged over the entire drainage basin) from the larger watershed and 1.1 inches of runoff from the smaller watershed.

Water-Resources Investigations Report↗
USGS2016

Selected low-flow frequency statistics for continuous-record streamgages in Georgia, 2013

This report presents the annual and monthly minimum 1- and 7-day average streamflows with the 10-year recurrence interval (1Q10 and 7Q10) for 197 continuous-record streamgages in Georgia. Streamgages used in the study included active and discontinued stations having a minimum of 10 complete climatic years of record as of September 30, 2013. The 1Q10 and 7Q10 flow statistics were computed for 85 streamgages on unregulated streams with minimal diversions upstream, 43 streamgages on regulated streams, and 69 streamgages known, or considered, to be affected by varying degrees of diversions upstream. Descriptive information for each of these streamgages, including the U.S. Geological Survey (USGS) station number, station name, latitude, longitude, county, drainage area, and period of record analyzed also is presented. Kendall’s tau nonparametric test was used to determine the statistical significance of trends in annual and monthly minimum 1-day and 7-day average flows for the 197 streamgages. Significant negative trends in the minimum annual 1-day and 7-day average streamflow were indicated for 77 of the 197 streamgages. Many of these significant negative trends are due to the period of record ending during one of the recent droughts in Georgia, particularly those streamgages with record through the 2013 water year. Long-term unregulated streamgages with 70 or more years of record indicate significant negative trends in the annual minimum 7-day average flow for central and southern Georgia. Watersheds for some of these streamgages have experienced minimal human impact, thus indicating that the significant negative trends observed in flows at the long-term streamgages may be influenced by changing climatological conditions. A Kendall-tau trend analysis of the annual air temperature and precipitation totals for Georgia indicated no significant trends. A comprehensive analysis of causes of the trends in annual and monthly minimum 1-day and 7-day average flows in central and southern Georgia is outside the scope of this study. Further study is needed to determine some of the causes, including both climatological and human impacts, of the significant negative trends in annual minimum 1-day and 7-day average flows in central and southern Georgia. To assess the changes in the annual 1Q10 and 7Q10 statistics over time for long-term continuous streamgages with significant trends in record, the annual 1Q10 and 7Q10 statistics were computed on a decadal accumulated basis for 39 streamgages having 40 or more years of record that indicated a significant trend. Records from most of the streamgages showed a decline in 7Q10 statistics for the decades of 1980–89, 1990–99, and 2000–09 because of the recent droughts in Georgia. Twenty four of the 39 streamgages had complete records from 1980 to 2010, and records from 23 of these gages exhibited a decline in the 7Q10 statistics during this period, ranging from –6.3 to –76.2 percent with a mean of –27.3 percent. No attempts were made during this study to adjust streamflow records or statistical analyses on the basis of trends. The monthly and annual 1Q10 and 7Q10 flow statistics for the entire period of record analyzed in the study are incorporated into the USGS StreamStatsDB, which is a database accessible to users through the recently released USGS StreamStats application for Georgia. StreamStats is a Web-based geographic information system that provides users with access to an assortment of analytical tools that are useful for water-resources planning and management, and for engineering design applications, such as the design of bridges. StreamStats allows users to easily obtain streamflow statistics, basin characteristics, and other information for user-selected streamgages.

Georgia↗
USGS2005

Summary of significant floods in the United States and Puerto Rico, 1994 through 1998 water years

This volume is a compilation of significant floods that occurred at streamgages throughout the United States and Puerto Rico from October 1, 1993, through September 30, 1998. A significant flood in this report refers to a peak-flow discharge(instantaneous or time averaged) that is in the top 5 percent of all the annual peak flows recorded at streamgages during their total period of record. Most of these floods are approximately equal to or greater than the 20-year recurrence interval flood (0.05 probability of occurrence in any 1 year) for that streamgage. A summary of the most devastating floods according to number of lives lost and amount of damage is provided for each water year from 1994 through 1998. Significant interstate floods also are described. For each year, national maps are provided showing percentage of streamgages in each State recording the significant floods and standardized deviations from long-term (1950-95) mean precipitation. Compilations arranged by State for each of the 50 United States and Puerto Rico also are presented. Each State compilation includes: (1) State maps to locate the streamgages recording significant floods and (2) tables of data that allow the reader to compare each significant flood during water years 1994 through 1998 with the maximum flood for the entire period of record at each streamgage.

Scientific Investigations Report↗
USGS2001

A field and statistical modeling study to estimate irrigation water use at Benchmark Farms study sites in southwestern Georgia, 1995-96

A benchmark irrigation monitoring network of farms located in a 32-county area in southwestern Georgia was established in 1995 to improve estimates of irrigation water use. A stratified random sample of 500 permitted irrigators was selected from a data base--maintained by the Georgia Department of Natural Resources, Georgia Environmental Protection Division, Water Resources Management Branch--to obtain 180 voluntary participants in the study area. Site-specific irrigation data were collected at each farm using running-time totalizers and noninvasive flowmeters. Data were collected and compiled for 50 farms for 1995 and 130 additional farms for the 1996 growing season--a total of 180 farms. Irrigation data collected during the 1996 growing season were compiled for 180 benchmark farms and used to develop a statistical model to estimate irrigation water use in 32 counties in southwestern Georgia. The estimates derived were developed from using a statistical approach know as "bootstrap analysis" that allows for the estimation of precision. Five model components--whether-to-irrigate, acres irrigated, crop selected, seasonal-irrigation scheduling, and the amount of irrigation applied--compose the irrigation model and were developed to reflect patterns in the data collected at Benchmark Farms Study area sites. The model estimated that peak irrigation for all counties in the study area occurred during July with significant irrigation also occurring during May, June, and August. Irwin and Tift were the most irrigated and Schley and Houston were the least irrigated counties in the study area. High irrigation intensity primarily was located along the eastern border of the study area; whereas, low irrigation intensity was located in the southwestern quadrant where ground water was the dominant irrigation source. Crop-level estimates showed sizable variations across crops and considerable uncertainty for all crops other than peanuts and pecans. Counties having the most irrigated acres showed higher variations in annual irrigation than counties having the least irrigated acres. The Benchmark Farms Study model estimates were higher than previous irrigation estimates, with 20 percent of the bias a result of underestimating irrigation acreage in earlier studies. Model estimates showed evidence of an upward bias of about 15 percent with the likely cause being a misrepresented inches-applied model. A better understanding of the causes of bias in the model could be determined with a larger irrigation sample size and increased substantially by automating the reporting of monthly totalizer amounts.

Georgia↗
USGS1962

Ground-water resources of Camas Prairie, Camas and Elmore Counties, Idaho

Camas Prairie is an eastward-trending intermontane basin along the north flank of the Snake River Plain in southern Idaho. The basin is about 40 miles long and averages about 8 miles wide. It was formed as a structural depression in which a considerable thickness of alluvial and lake deposits accumulated behind basalt flows, which at times blocked the outlet to the east. Intrusive and extrusive rocks of Cretaceous to Quarternary age enclose the basin on the north, west, and east. The enclosing rocks yield small amounts of water to springs and wells from the weathered mantle and fractures. The principal aquifers are sand and gravel in the alluvial fill, and basalt. Water in the shallow deposits is not confined, and the water table generally is less than 10 feet below the surface at most places. Ground water in the deeper deposits occurs chiefly in two horizons that comprise the upper and lower artesian aquifers. Throughout much of the prairie, the pressure is sufficient that water will flow from wells in these aquifers. Recharge to the basin is from direct precipitation and percolation of stream runoff from the bordering mountains. Ground water moves from the higher areas at the base of the encircling mountains toward the center of the basin and the eastern outlet. The artesian aquifers leak by upward percolation through the imperfectly confining beds and help maintain the shallow water table. Basalt, which interfingers with the alluvial deposits, is an important aquifer near the southeast margin of the prairie and at the east end. Annual recharge to the artesian aquifers is estimated to be about 40,000 acre-feet. Discharge from the artesian aquifers is about equally divided between upward leakage to the shallow aquifers and underflow out of the prairie. Most of the underflow discharges into Camas Creek or Magic Reservoir east of the prairie; little of the underflow reaches the Snake River Plain. Wells drilled for irrigation generally yield 500 to 1,200 gallons per minute from the artesian aquifers. Better construction and development methods would result in considerably better yields. Wells drilled in the basalt will yield 2,000 to 3,000 gallons per minute with moderate drawdowns. Computations made using aquifer coefficients, estimated on the basis of data collected during the investigation, suggest that 12,000 acre-feet of ground water might be withdrawn annually. However, the aquifers are limited in areal extent, and productivity of the alluvial aquifers is not great. Consequently heavy development would result in large drawdowns in wells, and there would be much interference between wells. The postulated large withdrawals from wells on the prairie would be supplied in part by a reduction in underflow from the prairie and in part by a decrease in leakage from the artesian aquifers, which in turn would cause a decline in the shallow water table.

Water Supply Paper↗
USGS2006

Water resources of Monroe County, New York, water years 2000-02: Atmospheric deposition, ground water, streamflow, trends in water quality, and chemical loads in streams

This report, the fifth in a series that presents analyses of the hydrologic data collected in Monroe County since 1984, interprets data from four surface-water-monitoring sites in the Irondequoit Creek basin (Irondequoit Creek at Railroad Mills, East Branch Allen Creek at Pittsford, Allen Creek near Rochester, and Irondequoit Creek above Blossom Road); and from three sites on tributaries to the Genesee River (Oatka Creek at Garbutt, Honeoye Creek at Honeoye Falls, and Black Creek at Churchville) and from the Genesee River at Charlotte Docks. It also interprets data from a site on Northrup Creek, which provides information on nutrient loads delivered to Long Pond, a small eutrophic embayment of Lake Ontario. The report also includes water-level and water-quality data from nine observation wells in Ellison Park, and atmospheric-deposition data from a collection site at Mendon Ponds. Atmospheric Deposition : Average annual precipitation for 2000–02 was 33.11 in., 0.94 in. below normal. Average annual loads of some chemical constituents in atmospheric deposition for 2000–02 differed considerably from those for the previous period of record. Loads of all nutrients except ammonia decreased by amounts ranging from 28 percent (ammonia + organic nitrogen and phosphorus) to 2 percent (nitrite + nitrate), whereas ammonia loads an increased by 8 percent. Loads of dissolved sodium and total zinc in atmospheric deposition increased by 56 percent, and 54, percent respectively, over the previous period of record. Average annual loads of other constituents showed decreases ranging from 41 percent (dissolved magnesium) to 17 percent (dissolved chloride). Loads of all nutrients deposited in the Irondequoit Creek basin from atmospheric sources during 2000–02 greatly exceeded those transported by Irondequoit Creek. The ammonia load deposited in the basin was 165 times the load transported at Blossom Road (the most downstream site); the ammonia + organic nitrogen load was 2.8 times greater, orthophosphate 9.7 times greater, total phosphorus 1.2 times greater, and the nitrite + nitrate load was 1.6 times greater. Average yields of dissolved chloride and dissolved sulfate from atmosphoric sources were much less than those transported by streamflow at Blossom Road—chloride was about 1.5 percent and sulfate about 9.1 percent of the amount transported by Irondequoit Creek. Ground water : Ground-water-levels and water quality data were collected from 9 observation wells in Ellison Park in Monroe County. All wells except Mo 2 and Mo 659 are in the flood plain of Irondequoit Creek. Water levels indicate frequent reversals in direction of lateral flow toward or away from Irondequoit Creek, and all wells except Mo2 and Mo 659 respond to water level fluctuations in the Creek. Trend tests on water levels for the period of record indicate a slight upward trend in water levels at all nine wells, two of which (Mo 3 and Mo 667) were statistically significant. Concentrations of ammonia and ammonia + organic nitrogen showed a general decrease for the current period of record. Total phosphorus concentrations showed an increase at four wells and a decrease at four wells. Water quality data showed that the highest median concentrations of nutrients continues to occur in Mo 667 and the highest median concentrations of common ions was at Mo 664. Streamflow : Statistical analysis of long-term (greater than 15 years) streamflow records for unregulated streams in Monroe County indicated that annual mean flows for water years (A water year is the 12-month period from October 1 through September 30 of the following year.) 2000–02 generally were in the normal range (75th to 25th percentile), although Allen Creek continued to show a significant downward trend in mean monthly streamflow during the 1984–2002 water years. Chemical Concentration in Streams : Concentrations of several constituents in streams of the Irondequoit Creek basin showed statistically significant (α = 0.05) trends from the beginning of their period of record through 2002. Three of the four Irondequoit Creek sites (Allen Creek, Blossom Road, and Railroad Mills) showed downward trends in ammonia (4.6 to 12.0 percent per year) and ammonia + organic nitrogen (2.8 to 5.3 percent per year). Allen Creek showed downward trends in nitrite + nitrate and total phosphorus (both 1.2 percent per year), and Irondequoit Creek above Blossom Road showed an upward trend in orthophosphate (1.8 percent per year). Three Irondequoit Creek sites showed upward trends in dissolved chloride: Railroad Mills (4.8 percent per year), Allen Creek, and Blossom Road (both 1.9 percent per year). Allen Creek showed a downward trend in sulfate of 0.98 percent per year, whereas Blossom Road showed a downward trend in suspended solids of 4.0 percent per year. Volatile suspended solids showed an upward trend of 3.2 percent per year at Allen Creek and a downward trend of 2.2 percent per year at Blossom Road. Northrup Creek in western Monroe County, showed significant downward trends in concentrations of volatile suspended solids (2.5 percent per year), total phosphorus (5.3 percent per year), and orthophosphate (9.9 percent per year). The Genesee River at Charlotte Docks showed downward trends in volatile suspended solids (2.1 percent per year) and ammonia + organic nitrogen (4.5 percent per year). Oatka Creek at Garbutt showed an upward trend of 21.4 percent per year in turbidity. Chemical Loads in Streams : Mean annual yields (pounds or tons per square mile) of many constituents at the Irondequoit Creek sites were lower than those in previous reporting periods. Suspended solids and nitrite + nitrate yields were lower at three of the sites, and yields of volatile suspended solids, ammonia, and total phosphorus were lower at two of the sites. East Branch Allen Creek showed lower yields for five of the nine constituents for 2000–02, than for previous reporting periods. The decreased yields at East Branch Allen Creek are likely due to the Jefferson Road stormflow-detention basin and the much lower than normal runoff for the 2000–02 period.

New York↗
USGS2008

Development of a Monitoring Protocol to Detect Ecological Change in the Intertidal Zone of Sitka National Historical Park, Alaska

A pilot study to develop and test a probability-based intertidal monitoring protocol for Sitka National Historical Park was conducted from 1999 to 2003. In 1999, the basic design, with a focus on sampling the whole of the designated intertidal was created, and sampling was conducted for sessile species and large mobile invertebrates by point-intercept sampling of vertical transects and band surveys along transects, respectively. In 2002 and 2003, the same types of sampling were conducted, but quadrat sampling for small mobile invertebrates was added and then modified. This project has produced basic data on the presence, abundance, and spatial distribution of substrates and intertidal biota. Additionally, statistical power analyses conducted on the biological data have allowed assessment of the ability of the sampling to detect trends in the abundance of the predominant species. Current sampling has an 80 percent probability to detect +10 percent annual changes in abundance of all targeted species with an a = 0.05; the ability to detect -10 percent trends is not as uniformly high. Various options are discussed for decreasing the spatial variance of the data. The information presented provides a basis for discussion of the major questions being asked, how the sampling design might be reconfigured to be consistent in approach, and how the intertidal monitoring should interface with other potential intertidal monitoring.

Scientific Investigations Report↗
USGS2016

Simulation of climate change effects on streamflow, groundwater, and stream temperature using GSFLOW and SNTEMP in the Black Earth Creek Watershed, Wisconsin

A groundwater/surface-water model was constructed and calibrated for the Black Earth Creek watershed in south-central Wisconsin. The model was then run to simulate scenarios representing common societal concerns in the basin, focusing on maintaining a cold-water resource in an urbanizing fringe near its upper stream reaches and minimizing downstream flooding. Although groundwater and surface water are considered a single resource, many hydrologic models simplistically simulate feedback loops between the groundwater system and other hydrologic processes. These feedbacks include timing and rates of evapotranspiration, surface runoff, soil-zone flow, and interactions with the groundwater system; however, computer models can now routinely and iteratively couple the surface-water and groundwater systems—albeit with longer model run times. In this study, preliminary calibrations of uncoupled transient surface-water and steady-state groundwater models were used to form the starting point for final calibration of one transient computer simulation that iteratively couples groundwater and surface water. The computer code GSFLOW (Groundwater/Surface-water FLOW) was used to simulate the coupled hydrologic system; a surface-water model represented hydrologic processes in the atmosphere, at land surface, and within the soil zone, and a groundwater-flow model represented the unsaturated zone, saturated zone, and streams. The coupled GSFLOW model was run on a daily time step during water years 1985–2007. Early simulation times (1985–2000) were used for spin-up to make the simulation results less sensitive to initial conditions specified; the spin-up period was not included in the model calibration. Model calibration used observed heads, streamflows, solar radiation, and snowpack measurements from 2000 to 2007 for history matching. Calibration was performed by using the PEST parameter estimation software suite. Simulated streamflows from the calibrated GSFLOW model and other basin characteristics were used as input to the one-dimensional SNTEMP (Stream-Network TEMPerature) model. SNTEMP was used to simulate daily stream temperature in selected stream reaches in the watershed. The temperature model was calibrated to high-resolution stream temperature time-series data measured in 2005. The calibrated GSFLOW and SNTEMP models were then used to simulate effects of potential climate change for the years 2010 through 2100. An ensemble of climate models and emission scenarios was evaluated. Downscaled climate drivers for the simulation period showed increases in maximum and minimum air temperature. Scenarios of future precipitation, however, did not show a monotonic trend like temperature. Uncertainty in the climate drivers increased with time for both temperature and precipitation. Forecasts of potential climate change scenarios showed growing season length increasing by weeks, and both potential and actual evapotranspiration rates increasing appreciably, in response to increasing air temperature. Simulated actual evapotranspiration rates increased less than simulated potential evapotranspiration rates as a result of water limitation in the root zone during the summer high-evapotranspiration period. The hydrologic-system response to climate change was characterized by a reduction in the importance of the snowmelt pulse and an increase in the importance of fall and winter groundwater recharge. The less dynamic hydrologic regime is likely to result in drier soil conditions, with relatively less drying expected in groundwater-fed systems. Groundwater discharge in the current upper cold-water reaches of Black Earth Creek is expected to decrease; flooding in downstream reaches may appreciably increase. The magnitude of changes in forecasted flow and associated groundwater/surface-water interaction is dependent on the General Circulation Model and emission scenario chosen. Potential future changes in air temperature drivers were consistently upward regardless of General Circulation Model and emission scenario selected; thus, simulated stream temperatures are forecast to increase appreciably with future climate. However, the amount of temperature increase was variable. Such uncertainty is reflected in temperature model results, along with uncertainty in the groundwater/surface-water interaction itself. The estimated increase in annual average temperature ranged from approximately 3 to 6 degrees Celsius by 2100 in the upper reaches of Black Earth Creek and 2 to 4 degrees Celsius in reaches farther downstream. As with all forecasts that rely on projections of an unknowable future, the results are best considered to approximate potential outcomes of climate change given the underlying uncertainty.

Wisconsin↗