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An initial-abstraction, constant-loss model for unit hydrograph modeling for applicable watersheds in Texas

Estimation of representative hydrographs from design storms, which are known as design hydrographs, provides for cost-effective, riskmitigated design of drainage structures such as bridges, culverts, roadways, and other infrastructure. During 2001?07, the U.S. Geological Survey (USGS), in cooperation with the Texas Department of Transportation, investigated runoff hydrographs, design storms, unit hydrographs,and watershed-loss models to enhance design hydrograph estimation in Texas. Design hydrographs ideally should mimic the general volume, peak, and shape of observed runoff hydrographs. Design hydrographs commonly are estimated in part by unit hydrographs. A unit hydrograph is defined as the runoff hydrograph that results from a unit pulse of excess rainfall uniformly distributed over the watershed at a constant rate for a specific duration. A time-distributed, watershed-loss model is required for modeling by unit hydrographs. This report develops a specific time-distributed, watershed-loss model known as an initial-abstraction, constant-loss model. For this watershed-loss model, a watershed is conceptualized to have the capacity to store or abstract an absolute depth of rainfall at and near the beginning of a storm. Depths of total rainfall less than this initial abstraction do not produce runoff. The watershed also is conceptualized to have the capacity to remove rainfall at a constant rate (loss) after the initial abstraction is satisfied. Additional rainfall inputs after the initial abstraction is satisfied contribute to runoff if the rainfall rate (intensity) is larger than the constant loss. The initial abstraction, constant-loss model thus is a two-parameter model. The initial-abstraction, constant-loss model is investigated through detailed computational and statistical analysis of observed rainfall and runoff data for 92 USGS streamflow-gaging stations (watersheds) in Texas with contributing drainage areas from 0.26 to 166 square miles. The analysis is limited to a previously described, watershed-specific, gamma distribution model of the unit hydrograph. In particular, the initial-abstraction, constant-loss model is tuned to the gamma distribution model of the unit hydrograph. A complex computational analysis of observed rainfall and runoff for the 92 watersheds was done to determine, by storm, optimal values of initial abstraction and constant loss. Optimal parameter values for a given storm were defined as those values that produced a modeled runoff hydrograph with volume equal to the observed runoff hydrograph and also minimized the residual sum of squares of the two hydrographs. Subsequently, the means of the optimal parameters were computed on a watershed-specific basis. These means for each watershed are considered the most representative, are tabulated, and are used in further statistical analyses. Statistical analyses of watershed-specific, initial abstraction and constant loss include documentation of the distribution of each parameter using the generalized lambda distribution. The analyses show that watershed development has substantial influence on initial abstraction and limited influence on constant loss. The means and medians of the 92 watershed-specific parameters are tabulated with respect to watershed development; although they have considerable uncertainty, these parameters can be used for parameter prediction for ungaged watersheds. The statistical analyses of watershed-specific, initial abstraction and constant loss also include development of predictive procedures for estimation of each parameter for ungaged watersheds. Both regression equations and regression trees for estimation of initial abstraction and constant loss are provided. The watershed characteristics included in the regression analyses are (1) main-channel length, (2) a binary factor representing watershed development, (3) a binary factor representing watersheds with an abundance of rocky and thin-soiled terrain, and (4) curve numb

Scientific Investigations Report

Groundwater chemistry and water-level elevations in bedrock aquifers of the Piceance and Yellow Creek watersheds, Rio Blanco County, Colorado, 2013–16

The Piceance and Yellow Creek watersheds in Rio Blanco County, Colorado, are known to contain important energy resources (oil shale and natural gas) and mineral resources (nahcolite). The primary sources of fresh groundwater in the Piceance and Yellow Creek watersheds are bedrock aquifers in the Uinta and Green River Formations. The aquifers are divided into an upper and lower aquifer separated by a regionally extensive semiconfining layer. These aquifers provide water to streams and springs in the watersheds and are an important resource to people living and working in the area. Development of energy and mineral resources has the potential to affect the quality of groundwater in several ways. The Bureau of Land Management and the U.S. Geological Survey began groundwater monitoring in 2010 to characterize the groundwater quality and water-level elevations of shallow bedrock aquifers in the Piceance and Yellow Creek watersheds. The purpose of this report is to present ground-water chemistry and water-level elevations collected during 2013–16. Comparisons are made to data that were collected from the bedrock aquifers from 2010 to 2012 to identify the potential for changes in water quality and water-level elevations. Appreciable changes in water-level elevations and hydraulic gradient were observed in early April 2015 in two wells completed in the upper and lower aquifers. The hydraulic gradient between the two wells was consistently downward from the upper aquifer to the lower aquifer during 2010–15; however, in early April 2015, the gradient changed from downward to upward between the two aquifers. Overall, water-level elevations declined by about 14 and 11 feet in the upper and lower aquifers, respectively, from 2013 to 2016. Previously published data estimated groundwater ages at 1,200 years old in the upper aquifer and 9,600 years old in the lower aquifer. These groundwater ages indicate that ground-water was recharged over thousands of years. With such long periods of time for aquifer recharge, declines in water-level elevation over short time steps (a few months) have important implications for sustainable management of this resource. Solution mining activities or drilling for oil and natural gas in the area could be related to the changes observed in water-level elevations in these wells; however, further investigation would be needed to evaluate causation. Changes in major-ion chemistry were evaluated in the bedrock aquifer using time series plots of select major-ion data from 2010 to 2016. Major-ion chemistry was variable for a single well from 2010 to 2016 where alkalinity and sulfate were the most variable constituents. One possible explanation for the observed changes in major-ion chemistry may be that the sample depth for that well no longer represents the most appreciable flow in the borehole. On a larger scale, potential changes in flow within the borehole may indicate changes in the regional flow system. Methane and volatile organic compound concentrations were evaluated using a similar approach to that of major ions and had similar findings. Methane concentrations in wells sampled from 2010 to 2016 were generally constant. The only exception was observed at a single well where the range of methane concentrations was from 57.4 (2010) to 4.02 milligrams per liter (2013). This is the same well where changes in water-level elevation, hydraulic gradient, and major-ion chemistry were observed, providing multiple lines of evidence to indicate change in the bedrock aquifers. Sampling of a well located in an area with little energy development but where faults or fractures could provide a path for the migration of fluids indicate mixing of groundwater between the upper and lower aquifers.

Colorado

Phase II modification of the W ater A vailability T ool for E nvironmental R esources (WATER) for Kentucky: The sinkhole-drainage process, point-and-click basin delineation, and results of karst test-basin simulations

This report describes Phase II modifications made to the Water Availability Tool for Environmental Resources (WATER), which applies the process-based TOPMODEL approach to simulate or predict stream discharge in surface basins in the Commonwealth of Kentucky. The previous (Phase I) version of WATER did not provide a means of identifying sinkhole catchments or accounting for the effects of karst (internal) drainage in a TOPMODEL-simulated basin. In the Phase II version of WATER, sinkhole catchments are automatically identified and delineated as internally drained subbasins, and a modified TOPMODEL approach (called the sinkhole drainage process, or SDP-TOPMODEL) is applied that calculates mean daily discharges for the basin based on summed area-weighted contributions from sinkhole drain-age (SD) areas and non-karstic topographically drained (TD) areas. Results obtained using the SDP-TOPMODEL approach were evaluated for 12 karst test basins located in each of the major karst terrains in Kentucky. Visual comparison of simulated hydrographs and flow-duration curves, along with statistical measures applied to the simulated discharge data (bias, correlation, root mean square error, and Nash-Sutcliffe efficiency coefficients), indicate that the SDPOPMODEL approach provides acceptably accurate estimates of discharge for most flow conditions and typically provides more accurate simulation of stream discharge in karstic basins compared to the standard TOPMODEL approach. Additional programming modifications made to the Phase II version of WATER included implementation of a point-and-click graphical user interface (GUI), which fully automates the delineation of simulation-basin boundaries and improves the speed of input-data processing. The Phase II version of WATER enables the user to select a pour point anywhere on a stream reach of interest, and the program will automatically delineate all upstream areas that contribute drainage to that point. This capability enables automatic delineation of a simulation basin of any size (area) and having any level of stream-network complexity. WATER then automatically identifies the presence of sinkholes catchments within the simulation basin boundaries; extracts and compiles the necessary climatic, topographic, and basin characteristics datasets; and runs the SDP-TOPMODEL approach to estimate daily mean discharges (streamflow).

Kentucky

Updating and recalibrating the integrated Santa Rosa Plain Hydrologic Model to assess stream depletion and to simulate future climate and management scenarios in Santa Rosa, Sonoma County, California

The Santa Rosa Plain Hydrologic Model (SRPHM) was developed and published in 2014 through a collaboration between the U.S. Geological Survey (USGS) and Sonoma Water to analyze the hydrologic system in the Santa Rosa Plain watershed, help meet the increasing demand for fresh water, and prepare for future uncertainties in water resources. The original model simulated hydrological conditions and water use from water years 1975 to 2010. Recently (2023), the USGS, in cooperation with Sonoma Water and the California State Water Resources Control Board, updated the SRPHM model to extend its simulation period to the end of the 2018 calendar year, incorporate new estimates of rural and agricultural water use, and use efficient input format for climate variables. The updated model was recalibrated, and evaluation of the new model calibration is included in this report. This report presents the results of comparing the hydraulic heads, streamflow, and groundwater budget simulated by the updated model with those generated by the original model and observed data. The main difference in the simulated budget between the original and updated SRPHM is the estimates of agricultural pumping, rural domestic pumping, and return flow generated from rural water use that was not simulated in the original model. The revised agricultural pumping is simulated using the agricultural package, which constrains pumping to available groundwater. The use of the agricultural package leads to a more realistic estimation of agricultural water use, with revised agricultural pumping being one-third less than that in the original model. The revised rural pumping is about half of the pumping in the original model because of using detailed parcel data to estimate population density in rural areas instead of coarse census tracts. Overall, average total inflows for water years 2006–10 simulated by the updated model were about 2 percent less than the original model, and the average total updated outflows were nearly 5 percent less than the original model. The updated model was then used to generate stream depletion maps, simulate climate change scenarios during 2019–99, and simulate water rights allocation using the Model for Decision Support in Integrated River Basin Management (MODSIM). The results from simulating eight future climate scenarios indicated either an increase in groundwater storage or no significant change in the next 80 years, along with an increase in recharge, an increase in actual evapotranspiration in six out of eight climate projections, and an increase in surface runoff. The increases in the simulated future groundwater storage, recharge, evapotranspiration, and runoff in most climate projections are mainly driven by the projected increase in precipitation in most of the future climate scenarios. The updated model also was used to test a pilot case study demonstrating water-resource allocation among different users with different water rights using the integrated MODSIM-Groundwater and Surface-Water Flow Model (GSFLOW) platform. The updated SRPHM serves as a valuable tool for analyzing historical and future hydrologic conditions in the Santa Rosa Plain watershed and preparing for future uncertainties.

California

Simulation of the regional groundwater-flow system of the Menominee Indian Reservation, Wisconsin

A regional, two-dimensional, steady-state groundwater-flow model was developed to simulate the groundwater-flow system and groundwater/surface-water interactions within the Menominee Indian Reservation. The model was developed by the U.S. Geological Survey (USGS), in cooperation with the Menominee Indian Tribe of Wisconsin, to contribute to the fundamental understanding of the region’s hydrogeology. The objectives of the regional model were to improve understanding of the groundwater-flow system, including groundwater/surface-water interactions, and to develop a tool suitable for evaluating the effects of potential regional water-management programs. The computer code GFLOW was used because of the ease with which the model can simulate groundwater/surface-water interactions, provide a framework for simulating regional groundwater-flow systems, and be refined in a stepwise fashion to incorporate new data and simulate groundwater-flow patterns at multiple scales. Simulations made with the regional model reproduce groundwater levels and stream base flows representative of recent conditions (1970–2013) and illustrate groundwater-flow patterns with maps of (1) the simulated water table and groundwater-flow directions, (2) probabilistic areas contributing recharge to high-capacity pumped wells, and (3) estimation of the extent of infiltrated wastewater from treatment lagoons. The groundwater-flow model described in this report simulates the major hydrogeologic features of the modeled area, including surficial unconsolidated aquifers, groundwater/surface-water interactions, and groundwater withdrawals from existing high-capacity production wells. Areas contributing recharge to pumped high-capacity wells on the Menominee Indian Reservation were delineated by tracking simulated water particles from the water table to wells in combination with Monte Carlo techniques, and maps of the probability of capture for each well nest were produced. Groundwater-agebased areas contributing recharge to wells were simulated by using the calibrated set of parameters and porosity values adjusted to account for bias in simulated saturated thickness. Simulations were performed for current (2013) pumping rates. The simulations show a range in sensitivity of the simulated areas contributing recharge to wells given the parameters evaluated through the Monte Carlo analysis. The areas contributing recharge to supply wells for the villages of Zoar and Neopit are long and narrow, with a sharp gradation from high to low probability of capture. The areas contributing recharge to supply wells for Middle Village and the village of Keshena exhibit a sharp gradation from high to low probability over a relatively small area between the well and a local groundwater mound. The highest probability areas contributing recharge to the supply wells for the Villages of Onekewat and Redwing are in the immediate vicinity of the wells. These wells also have an extensive area with low probability for capturing water that is likely due to a locally low hydraulic gradient and the large degree of uncertainty associated with the lakebed resistance parameters that control interaction between groundwater and local lakes. Additional field investigations and associated local model refinements would facilitate further reductions in uncertainty associated with simulated areas contributing recharge to the wells. The likely extent of the Neopit wastewater plume was simulated by using the groundwater-flow model and Monte Carlo techniques to evaluate the sensitivity of predictive simulations to a range of model parameter values. Wastewater infiltrated from the currently operating lagoons flows predominantly south toward Tourtillotte Creek. Some of the infiltrated wastewater is simulated as having a low probability of flowing beneath Tourtillotte Creek to the nearby West Branch Wolf River. Results for the probable extent of the wastewater plume are considered to be qualitative because the method only considers advective flow and does not account for processes affecting contaminant transport in porous media. Therefore, results for the probable extent of the wastewater plume are sensitive to the number of particles used to represent flow from the lagoon and the resolution of a synthetic grid used for the analysis. Nonetheless, it is expected that the qualitative results may be of use for identifying potential downgradient areas of concern that can then be evaluated using the quantitative “area contributing recharge to wells” method or traditional contaminant-transport simulations.

Wisconsin

Hydrogeologic characteristics of the St. Croix River basin, Minnesota and Wisconsin: Implications for the susceptibility of ground water to potential contamination

Population growth in the St. Croix River Basin in Minnesota and Wisconsin has intensified concerns of county resource managers and the National Park Service, which is charged with protecting the St. Croix National Scenic Riverway, about the potential for ground-water contamination in the basin. This report describes a previously developed method that was adapted to illustrate potential ground-water-contamination susceptibility in the St. Croix River Basin. The report also gives an estimate of ground-water-residence time and surface-water/ground-water interaction as related to natural attenuation and movement of contaminants in five tributary basins. A ground-water-contamination-susceptibility map was adapted from a state-wide map of Wisconsin to the St. Croix River Basin by use of well-driller construction records and regional maps of aquifer properties in Minnesota and Wisconsin. Measures of various subsurface properties were combined to generate a spatial index of susceptibility. The subjective index method developed for the State of Wisconsin by Schmidt (1987) 1 was not derived from analyses of water-quality data or physical processes. Nonetheless, it was adapted for this report to furnish a seamless map across state boundaries that would be familiar to many resource managers. Following this method, areas most susceptible to contamination appear to have coarse-grained sediments (sands or gravels) and shallow water tables or are underlain by carbonate-bedrock aquifers. The least susceptible areas appear to have fine-grained sediments and deep water tables. If an aquifer becomes contaminated, the ground-water-residence time can affect potential natural attenuation along the ground-water-flow path. Mean basin ground-water-residence times were computed for the Apple, Kettle, Kinnickinnic, Snake and Sunrise River Basins, which are tributary basins to the St. Croix Basin, by use of average aquifer properties of saturated thickness, porosity, and recharge rates. The Apple River Basin had the shortest mean ground-water-residence times (20–120 years), owing largely to the moderate saturated thickness and high recharge rate in the basin. The Kinnickinnic and Sunrise River Basins had the longest mean residence times (60–350 and 70–390 years, respectively) chiefly because of the relatively large saturated thickness of the basins. Owing to limitations of the residence-time calculations, actual ground-water-residence times will vary around the mean values within each basin and may range from days or weeks in karst carbonate aquifers to millennia in deep confined sandstone aquifers. Areas of relatively short residence time (less than the median residence time in each basin) were identified by use of ground-water-flow models for each of the five tributary basins. Results of simulations show that these areas, in which contaminants may have relatively less time for natural attenuation along the short flow paths, generally occur near streams and rivers where ground water discharges to the surface. Finally, the ground-water-flow models were used to simulate ground-water/surface-water interaction in the five tributary basins. Results of simulations show that some lakes and reservoirs leak surface water into the ground-water-flow system on their downgradient side, where the surface-water outflow has been restricted by a dam or a naturally constricted outlet. These locations are noteworthy because contaminated surface waters could potentially enter the ground-water-flow system at these locations.

Minnesota, Wisconsin

Water quality of the Little Arkansas River and Equus Beds Aquifer before and concurrent with large-scale artificial recharge, south-central Kansas, 1995-2012

The city of Wichita artificially recharged about 1 billion gallons of water into the Equus Beds aquifer during 2007–2012 as part of Phase I recharge of the Artificial Storage and Recovery project. This report, prepared in cooperation by the U.S. Geological Survey and the city of Wichita, Kansas, summarizes Little Arkansas River (source-water for artificial recharge) and Equus Beds aquifer water quality before (1995–2006) and during (2007–2012) Artificial Storage and Recovery Phase I recharge. Additionally, aquifer water-quality distribution maps are presented and water-quality changes associated with Phase I recharge timing are described. Computed chloride concentrations in the Little Arkansas River exceeded the Federal secondary maximum contaminant level (SMCL) about 20 percent of the time during 1999 through 2012, primarily during low-flow conditions. Groundwater chloride concentrations during 2001 through 2012 exceeded the SMCL in about 6 percent of shallow wells and 7 percent of deep wells, primarily near Burrton, Kansas and along the Arkansas River. Nearly all surface water nitrate plus nitrite concentrations during 1995 through 2012 were less than the Federal maximum contaminant level (MCL); groundwater nitrate plus nitrite concentrations exceeded the MCL in about 16 percent of shallow groundwater samples and were minimal in the deeper parts of the aquifer. Several trace elements frequently exceeded drinking water criteria, including arsenic, iron, and manganese. Recharge activities at Phase I recharge wells have not resulted in substantial effects on groundwater quality in the area, likely because the total amount of water recharged is relatively small (1 billion gallons) compared to aquifer storage volume (greater than 990 billion gallons in winter 2012). The eastward movement of the Burrton chloride plume is likely being slowed by a line of recharge locations associated with Phase I; however, chloride concentrations in deep groundwater still advanced to less than one half mile from the central part of the study area. Water-quality constituents of concern (major ions, nutrients, trace elements, triazine herbicides, and fecal indicator bacteria) have not increased substantially and are likely more affected by climatological (natural recharge by precipitation) and natural (geochemical oxidation/reduction, metabolic and decay rates) processes than artificial recharge. Arsenic remains a water-quality constituent of concern because of natural and continued persistence of concentrations exceeding the Federal maximum contaminant level of 10 micrograms per liter, especially in the deeper parts of the Equus Beds aquifer.

Kansas

Design and Performance of an Enhanced Bioremediation Pilot Test in a Tidal Wetland Seep, West Branch Canal Creek, Aberdeen Proving Ground, Maryland

Because of a lack of available in situ remediation methods for sensitive wetland environments where contaminated groundwater discharges, the U.S. Geological Survey, in cooperation with the U.S. Army Garrison, Aberdeen Proving Ground, Maryland, conceived, designed, and pilot tested a permeable reactive mat that can be placed horizontally at the groundwater/surface-water interface. Development of the reactive mat was part of an enhanced bioremediation study in a tidal wetland area along West Branch Canal Creek at Aberdeen Proving Ground, where localized areas of preferential discharge (seeps) transport groundwater contaminated with carbon tetrachloride, chloroform, tetrachloroethene, trichloroethene, and 1,1,2,2-tetrachloroethane from the Canal Creek aquifer to land surface. The reactive mat consisted of a mixture of commercially available organic- and nutrient-rich peat and compost that was bioaugmented with a dechlorinating microbial consortium, WBC-2, developed for this study. Due to elevated chlorinated methane concentrations in the pilot test site, a layer of zero-valent iron mixed with the peat and compost was added at the base of the reactive mat to promote simultaneous abiotic and biotic degradation. The reactive mat for the pilot test area was designed to optimize chlorinated volatile organic compound degradation efficiency without altering the geotechnical and hydraulic characteristics, or creating undesirable water quality in the surrounding wetland area, which is referred to in this report as achieving geotechnical, hydraulic, and water-quality compatibility. Optimization of degradation efficiency was achieved through the selection of a sustainable organic reactive matrix, electron donor, and bioaugmentation method. Consideration of geotechnical compatibility through design calculations of bearing capacity, settlement, and geotextile selection showed that a 2- to 3-feet tolerable thickness of the mat was possible, with 0.17 feet settlement predicted for unconsolidated sediments between 1.5 and 6 years following installation of the reactive mat. To ensure hydraulic compatibility in the mat design, mat materials that had a hydraulic conductivity greater than the surrounding wetland sediments were selected, and the mixture was optimized to consist of 1.5 parts compost, 1.5 parts peat and 1 part sand as a safeguard against fluidization. Sediment and matrix properties also indicated that a nonwoven geotextile with a cross-plane flow greater than that of the native sediments was suitable as the base of the reactive mat. Another nonwoven geotextile was selected for installation between the iron mix and organic zones of the mat to create more laminar flow conditions within the mat. Total metals and sequential extraction procedure analyses of mat materials, which were conducted to evaluate water-quality compatibility of the mat materials, showed that concentrations of metals in the compost ranged from one-half to one order of magnitude below consensus-based probable effect concentrations in sediment. A 22-inch-thick reactive mat, containing 0.5 percent WBC-2 by volume, was constructed at seep area 3-4W and monitored from October 2004 through October 2005 for the pilot test. No local, immediate failure of the mat or of wetland sediments was observed during mat installation, indicating that design estimates of bearing capacity and geotextile textile selection ensured the integrity of the mat and wetland sediments during and following installation. Measurements of surface elevation of the mat showed an average settlement of the mat surface of approximately 0.25 feet after 10 months, which was near the predicted settlement for unconsolidated sediment. Monitoring showed rapid establishment and sustainment throughout the year of methanogenic conditions conducive to anaerobic biodegradation and efficient dechlorination activity by WBC-2. The median mass removal of chloromethanes and total chloroethenes and ethane during the

Scientific Investigations Report

Water budgets for selected watersheds in the Delaware River basin, eastern Pennsylvania and western New Jersey

This pilot study, done by the U.S. Geological Survey in cooperation with the Delaware River Basin Commission, developed annual water budgets using available data for five watersheds in the Delaware River Basin with different degrees of urbanization and different geological settings. A basin water budget and a water-use budget were developed for each watershed. The basin water budget describes inputs to the watershed (precipitation and imported water), outputs of water from the watershed (streamflow, exported water, leakage, consumed water, and evapotranspiration), and changes in ground-water and surface-water storage. The water-use budget describes water withdrawals in the watershed (ground-water and surface-water withdrawals), discharges of water in the watershed (discharge to surface water and ground water), and movement of water of water into and out of the watershed (imports, exports, and consumed water). The water-budget equations developed for this study can be applied to any watershed in the Delaware River Basin. Data used to develop the water budgets were obtained from available long-term meteorological and hydrological data-collection stations and from water-use data collected by regulatory agencies. In the Coastal Plain watersheds, net ground-water loss from unconfined to confined aquifers was determined by using ground-water-flow-model simulations. Error in the water-budget terms is caused by missing data, poor or incomplete measurements, overestimated or underestimated quantities, measurement or reporting errors, and the use of point measurements, such as precipitation and water levels, to estimate an areal quantity, particularly if the watershed is hydrologically or geologically complex or the data-collection station is outside the watershed. The complexity of the water budgets increases with increasing watershed urbanization and interbasin transfer of water. In the Wissahickon Creek watershed, for example, some ground water is discharged to streams in the watershed, some is exported as wastewater, and some is exported for public supply. In addition, ground water withdrawn outside the watershed is imported for public supply or imported as wastewater for treatment and discharge in the watershed. A GIS analysis was necessary to quantify many of the water-budget components. The 89.9-square mile East Branch Brandywine Creek watershed in Pennsylvania is a rural watershed with reservoir storage that is underlain by fractured rock. Water budgets were developed for 1977-2001. Average annual precipitation, streamflow, and evapotranspiration were 46.89, 21.58, and 25.88 inches, respectively. Some water was imported (average of 0.68 inches) into the watershed for public-water supply and as wastewater for treatment and discharge; these imports resulted in a net gain of water to the watershed. More water was discharged to East Branch Brandywine Creek than was withdrawn from it; the net discharge resulted in an increase in streamflow. Most ground water was withdrawn (average of 0.25 inches) for public-water supply. Surface water was withdrawn (average of 0.58 inches) for public-water and industrial supply. Discharge of water by sewage-treatment plants and industries (average of 1.22 inches) and regulation by Marsh Creek Reservoir caused base flow to appear an average of 7.2 percent higher than it would have been without these additional sources. On average, 67 percent of the difference was caused by sewage-treatment-plant and industrial discharges, and 33 percent was caused by regulation of the Marsh Creek Reservoir. Water imports, withdrawals, and discharges have been increasing as the watershed becomes increasingly urbanized. The 64-square mile Wissahickon Creek watershed in Pennsylvania is an urban watershed underlain by fractured rock. Water budgets were developed for 1987-98. Average annual precipitation, streamflow, and evapotranspiration were 47.23, 22.24, and 23.12 inches, respectively. The watershed is highly u

Pennsylvania

Estimates of gains and losses from unmeasured sources and sinks for streamflow and dissolved-solids load in selected reaches of the Arkansas River, southeastern Colorado, 2009-2010

The Arkansas River is an important municipal water supply and is the primary supply for about 400,000 acres of irrigated land in southeastern Colorado. The suitability of this water for domestic, agricultural, and industrial use is affected by high salinity in parts of the Arkansas River. There is a need to quantify mass loading of dissolved solids (DS) in the Arkansas River. In 2009, the U.S. Geological Survey, in cooperation with the Arkansas River Basin Regional Resource Planning Group and the Colorado Water Conservation Board, began a study to estimate gains and losses from unmeasured sources and sinks for streamflow and DS load in selected reaches of the Arkansas River in southeastern Colorado. Two study reaches were selected for investigation—Canon City to just upstream from Pueblo Reservoir (UARB) and Avondale to Las Animas (LARB). The results from the water-budget analyses indicated that potential areas of unmeasured sources and sinks of streamflow were identifiable in the two study reaches. In the UARB, a substantial volume of water in the subreach from Ark at Canon City to the seasonal gaging station 5 miles downstream (Ark nr Canon City) was unaccounted for by the methodology used in this analysis. The daily gain from unmeasured sources in this subreach was estimated to be about 100 cubic feet per second (ft 3 /s) or about 20 ft 3 /s per river mile. Water-budget estimates for the remaining 18 miles of the UARB study reach indicated that gains or losses from unmeasured sources or sinks were within the measurement error as defined for this report. In the LARB, gains and losses from unmeasured sources and sinks were identified in some of the subreaches but the magnitude of the flux generally was small. Unmeasured sources ranging from less than 2 to 3 ft 3 /s per mile were identified in the river subreaches from Ark at Catlin Dam downstream to Ark at Swink. A streamflow loss was indicated along the subreach from Ark at Nepesta to Ark at Catlin Dam, particularly in 2010. The mechanism and spatial extent of this sink was not identified, and further investigation would be required to better quantify the loss. The results from the analyses of unmeasured sources of DS load indicated that potential source areas were identifiable in the study areas. It might be expected that unmeasured DS load flux would be identified along the same reaches where unmeasured streamflow flux was identified. To that extent, some of the observed results from the analysis of daily DS loading did mirror the streamflow results. In some subreaches of the Arkansas River, however, unmeasured sources and sinks of DS load did not appear to be directly associated with unmeasured sources and sinks of streamflow. In the UARB from Ark at Canon City to Ark nr Canon City, unmeasured gains in DS load were estimated to range from 11 to 22 tons per day per mile in 2009 and from about 8 to 13 tons per day per mile in 2010; streamflow from unmeasured sources was estimated to be about 20 ft 3 /s per mile along this same reach. Downstream from this short reach, DS load to the river from unmeasured sources was estimated to range from 5.4 to 7.6 tons per day per mile in 2010 for Ark nr Canon City to Ark at Portland and from 11 to 16 tons per day per mile in 2009 for Ark at Portland to Ark nr Portland. Unmeasured gains in streamflow were not identified in either of these subreaches. Several small tributaries with DS concentrations ranging from 3,000 mg/L to as high as 6,000 mg/L enter the river along these subreaches. These inputs may indicate a potential source of groundwater that could affect DS loading in the river. Further investigation would be needed to identify the unmeasured source or sources of DS load to determine the nature and extent of unmeasured inputs. In the LARB, gains in DS load from unmeasured sources were identified for the subreach from Ark nr Avondale to Ark at Nepesta, although no substantial amounts of streamflow from unmeasured sources were identified for this subreach. In 2009, the estimated gain in DS load from unmeasured sources for this subreach was 4.7 tons per day per mile. An increase in DS load from unmeasured sources also was identified along the subreach of the river from Ark at Catlin to Swink; the DS load from unmeasured sources was estimated to range from 10 to 28 tons per day per mile. The only loss of DS load was identified for the subreach from Nepesta to Catlin Dam in 2010. The mechanism and spatial extent of the losses were not identified, and further investigation would be required to better understand the results.

Colorado

Groundwater-quality monitoring program in Chester County, Pennsylvania, 1980-2008

The U.S. Geological Survey in cooperation with the Chester County Water Resources Authority and the Chester County Health Department began a groundwater-quality monitoring program in 1980 in Chester County, Pa., where a large percentage of the population relies on wells for drinking-water supply. This report documents the program and serves as a reference for data collected through the program from 1980 through 2008. The initial focus of the program was to collect data on groundwater quality near suspected localized sources of contamination, such as uncontrolled landfills and suspected industrial wastes, to determine if contaminants were present that might pose a health risk to those using the groundwater. Subsequently, the program was expanded to address the effects of widely distributed contaminant sources associated with agricultural and residential land uses on groundwater quality and to document naturally occurring constituents, such as radium, radon, and arsenic, that are potential hazards in drinking water. Since 2000, base-flow stream samples have been collected in addition to well-water and spring samples in a few small drainage areas to investigate the relation between groundwater quality measured in well samples and streams. The program has primarily consisted of spatial assessment with limited temporal data collected on groundwater quality. Most data were collected through the monitoring program for reconnaissance purposes to identify and locate groundwater-quality problems and generally were not intended for rigorous statistical analyses that might determine land-use or geochemical factors affecting groundwater quality in space or through time. Results of the program found several contaminants associated with various land uses and human activities in groundwater in Chester County. Volatile organic compounds (such as trichloroethylene) were measured in groundwater near suspected localized contaminant sources in concentrations that exceeded drinking-water standards. Groundwater in some agricultural areas had concentrations of nitrate and some pesticides that exceeded drinking-water standards. Elevated concentrations of chloride were measured near salt storage areas and highways. Formaldehyde was detected in groundwater near cemeteries. In residential areas with on-site wastewater disposal, effects on groundwater quality included elevated nitrate concentrations and low concentrations of volatile organic compounds and wastewater compounds, such as antibiotics and detergents. Base-flow samples indicated that groundwater discharge to streams carried contaminants such as nitrate, pesticides, wastewater compounds, and other contaminants. Radionuclides, including radium-226, radium-228, radium-224, and radon-222, and gross alpha-particle activity were measured in groundwater at levels above established and proposed drinking-water standards in some geologic units, particularly in quartzite and quartzite schists. Arsenic concentrations above drinking-water standards were measured in a few samples and were most likely to occur in groundwater in the shales and sandstones in the northern part of the county. Other potential natural hazards, such as lead from aquifer materials or leached from plumbing because of pH, were present in concentrations above drinking-water standards infrequently (less than 10 percent of samples). Limited temporal sampling suggested that chloride concentrations in groundwater increased in the county since the program began in 1980 through 2008, reflecting increasing population and urbanization in that period.

Scientific Investigations Report

Chloride in ground water and surface water in the vicinity of selected surface-water sampling sites of the beneficial use monitoring program of Oklahoma, 2003

The Oklahoma Water Resources Board Beneficial Use Monitoring Program reported exceedances of beneficial-use standards for chloride at 11 surface-water sampling sites from January to October 2002. The U.S. Geological Survey, in cooperation with the Oklahoma Department of Environmental Quality, conducted a study to determine the chloride concentrations in ground water in the vicinity of Beneficial Use Monitoring Program surface-water sampling sites not meeting beneficial use standards for chloride and compare chloride concentrations in ground water and surface water. The chloride-impaired Beneficial Use Monitoring Program surface-water sampling sites are located in the western and southern regions of Oklahoma. The ground-water sampling sites were placed in proximity to the 11 surface-water sampling sites designated impaired by chloride by the Oklahoma Water Resources Board. Two surface-water sampling sites were located on the Beaver River (headwaters of the North Canadian River), three sites on the Cimarron River, one site on Sandy Creek, one site on North Fork Red River, and four sites on the Red River. Six ground-water samples were collected, when possible, from two test holes located upstream from each of the 11 Beneficial Use Monitoring Program surface-water sampling sites. One test hole was placed on the left bank and right bank, when possible, of each Beneficial Use Monitoring Program surfacewater sampling site. All test holes were located on alluvial deposits adjacent to the Beneficial Use Monitoring Program surface-water sampling sites within 0.5 mile of the stream. Top, middle, and bottom ground-water samples were collected from the alluvium at each test hole, when possible. Water properties of specific conductance, pH, water temperature, and dissolved oxygen were recorded in the field before sampling for chloride. The ground-water median chloride concentrations at 8 of the 11 Beneficial Use Monitoring Program sites were less than the surface-water median chloride concentrations. The Turpin and Beaver sites had similar ground-water and surface-water median chloride concentrations. The Buffalo site was the only site that had a large difference between the ground-water and surface-water chloride concentrations. The ground-water median chloride concentration was approximately 14,500 mg/L greater than the surface-water median chloride concentration at the Buffalo site.

Scientific Investigations Report

Permeable groundwater pathways and tritium migration patterns from the HANDLEY underground nuclear test, Pahute Mesa, Nevada

The HANDLEY nuclear test was detonated at about 2,700 feet below the water table on March 26, 1970, in Pahute Mesa, south-central Nevada. Measured tritium concentrations in boreholes ER-20-12 and PM-3 indicate that a shallow tritium plume has migrated more than 1 mile (mi) downgradient from the HANDLEY test within a semi-perched aquifer and deeper tritium plumes have migrated 4.5 miles (mi) within underlying regional aquifers. Boreholes ER-20-12 and PM-3 are in an area of moderate-to-low transmissivity, but observation of tritium moving 4.5 mi within 40 years of the detonation indicates that high-transmissivity intervals exist. However, the location of these permeable pathways is unknown. This report integrates geologic, hydrologic, and tritium data to infer the location of permeable pathways near and downgradient from the HANDLEY test. Numerical groundwater-flow and tritium-transport models were developed to estimate hydraulic and transport properties between the HANDLEY test and boreholes ER-20-12 and PM-3 . Recharge, hydraulic-conductivity, specific-yield, specific-storage, and effective-porosity distributions were estimated with the numerical models by fitting simulated water-level altitudes, vertical-head differences, aquifer-test transmissivities, tritium concentrations, and drawdowns in wells PM-3-1 and PM-3-2 to measured equivalents. Drawdowns were estimated in wells PM-3-1 and PM-3-2 in response to groundwater withdrawals during the drilling of borehole ER-20-12 . A modified hydrostratigraphic framework model (mHFM) was developed that incorporates hydrostratigraphic units (HSUs) from the Pahute Mesa–Oasis Valley hydrostratigraphic framework model (PMOV HFM). HSUs in the mHFM were modified from the PMOV HFM by grouping HSUs that, conceptually, are hydraulically similar and splitting HSUs based on water-level, aquifer-test, and tritium data. Shallow and deeper tritium plumes have migrated to borehole ER-20-12 from the HANDLEY test. The shallow plume migrated from the HANDLEY test through the Timber Mountain welded tuff aquifer, whereas the deeper plumes moved through the Belted Range aquifer (BRA) and modified pre-Belted Range lava flow aquifer (mPBRLFA). Simulated tritium concentrations indicate that the leading edges of tritium plumes reached borehole ER-20-12 by 1990. From 1970 to 2020, the simulated tritium load mostly occurs between borehole ER-20-12 and the HANDLEY test. An unmapped permeable feature was simulated between borehole ER-20-12 and the downgradient Ribbon Cliff structural zone. This permeable feature hydraulically connects the BRA and mPBRLFA with the Tiva Canyon aquifer (TCA). The TCA is the most transmissive unit in the study area. Simulated tritium from the deeper plumes moves through the permeable feature downgradient from borehole ER-20-12 and then migrates toward well PM-3-1 through the TCA. The leading edge of the deeper simulated tritium plumes reaches well PM-3-1 by 2010. The mHFM and PMOV HFM do not include a permeable HSU at the water table near borehole PM-3 , which is necessary for numerical flow and transport models to match measured water levels, transmissivities, and tritium concentrations in well PM-3-2 . Consistently higher measured tritium concentrations in shallow well PM-3-2 , compared to deeper well PM-3-1 , and a downward vertical gradient between these wells indicate that a permeable feature exists near the water table that causes faster tritium migration toward the shallow well. Reevaluation of the PMOV HFM and geologic investigations, such as drilling another well, are needed to more precisely understand the shallow permeable pathway from the Handley test to well PM-3-2 .

Nevada

Water Use in Oklahoma 1950-2005

Comprehensive planning for water resources development and use in Oklahoma requires a historical perspective on water resources. The U.S. Geological Survey, in cooperation with the Oklahoma Water Resources Board, summarized the 1950-2005 water-use information for Oklahoma. This report presents 1950-2005 estimates of freshwater withdrawal for water use in Oklahoma by source and category in 5-year intervals. Withdrawal source was either surface water or groundwater. Withdrawal categories include: public supply, irrigation, livestock and aquaculture, thermoelectric-power generation (cooling water), domestic and commercial, and industrial and mining. Withdrawal data were aggregated and tabulated by county, major river basin, and principal aquifer. The purpose of this report is to summarize water-use data in Oklahoma through: (1) presentation of detailed information on freshwater withdrawals by source, county, major river basin, and principal aquifer for 2005; (2) comparison of water use by source, category, major river basin, and principal aquifer at 5-year intervals from 1990-2005; and (3) comparison of water use on a statewide basis by source and category at 5-year intervals from 1950-2005. Total withdrawals from surface-water and groundwater sources during 2005 were 1,559 million gallons per day-989 million gallons a day or 63 percent from surface-water sources and 570 million gallons per day or 37 percent from groundwater sources. The three largest water use categories were: public supply, 646 million gallons per day or 41 percent of total withdrawals; irrigation, 495 million gallons per day or 32 percent of total withdrawals; and livestock and aquaculture, 181 million gallons per day or 12 percent of total withdrawals. All other categories were 237 million gallons per day or 15 percent of total withdrawals. The influence of public supply on the total withdrawals can be seen in the eastern two-thirds of Oklahoma; whereas, the influence of irrigation on total withdrawals can be seen in the western third of Oklahoma. Surface-water sources were dominant in the eastern half of Oklahoma and groundwater sources were dominant in the western half of Oklahoma. Public supply withdrawals increased steadily from 1990-2000 and then decreased slightly in 2005, mainly because of a decrease in surface-water withdrawals. Irrigation withdrawals increased from 1990-1995 and then decreased steadily to 2005. Total livestock and aquaculture withdrawals steadily increased from 1990-2005. The largest increase in the other categories was for thermoelectric power generation that has steadily increased and almost doubled from 1990-2005. Surface-water sources have been increasing in importance from 1950-2005, in part because of the increasing percentage of surface-water for public supply as the total population of Oklahoma and population served by surface-water sources increased. Groundwater sources have been generally decreasing in importance as a percentage of total withdrawals in recent years. However, the magnitude of groundwater withdrawals was greatly dependent on irrigation withdrawals and specifically irrigated acreage in the panhandle.

Scientific Investigations Report

Potential water-quality effects of coal-bed methane production water discharged along the upper Tongue River, Wyoming and Montana

Water quality in the upper Tongue River from Monarch, Wyoming, downstream to just upstream from the Tongue River Reservoir in Montana potentially could be affected by discharge of coal-bed methane (CBM) production water (hereinafter referred to as CBM discharge). CBM discharge typically contains high concentrations of sodium and other ions that could increase dissolved-solids (salt) concentrations, specific conductance (SC), and sodium-adsorption ratio (SAR) in the river. Increased inputs of sodium and other ions have the potential to alter the river's suitability for agricultural irrigation and aquatic ecosystems. Data from two large tributaries, Goose Creek and Prairie Dog Creek, indicate that these tributaries were large contributors to the increase in SC and SAR in the Tongue River. However, water-quality data were not available for most of the smaller inflows, such as small tributaries, irrigation-return flows, and CBM discharges. Thus, effects of these inflows on the water quality of the Tongue River were not well documented. Effects of these small inflows might be subtle and difficult to determine without more extensive data collection to describe spatial patterns. Therefore, synoptic water-quality sampling trips were conducted in September 2005 and April 2006 to provide a spatially detailed profile of the downstream changes in water quality in this reach of the Tongue River. The purpose of this report is to describe these downstream changes in water quality and to estimate the potential water-quality effects of CBM discharge in the upper Tongue River. Specific conductance of the Tongue River through the study reach increased from 420 to 625 microsiemens per centimeter (.μS/cm; or 49 percent) in the downstream direction in September 2005 and from 373 to 543 .μS/cm (46 percent) in April 2006. Large increases (12 to 24 percent) were measured immediately downstream from Goose Creek and Prairie Dog Creek during both sampling trips. Increases attributed to direct CBM discharges were smaller. In September 2005, the SC of 12 measured CBM discharges ranged from 1,750 to 2,440 .μS/cm, and the combined discharges increased SC in the river by an estimated 4.5 percent. In April 2006, the SC of eight measured CBM discharges ranged from 1,720 to 2,070 μS/cm; the largest of these discharges likely increased SC in the river by 5.8 percent. Estimates of potential effects of the CBM discharges on the SC of the Tongue River near the Tongue River Reservoir were calculated using a two-step process involving linear regression and mass-balance calculations for a range of streamflow and CBM-discharge conditions. Potential effects from CBM discharges are larger increases of SC and SAR at lower flows than at higher flows and relative increases that are substantially smaller for SC than for SAR. For example, if the streamflow was 100 cubic feet per second (ft 3 /s) in the Tongue River near the Tongue River Reservoir and CBM discharge ranged from 1,250 to 5,000 gallons per minute, the projected increases would range from 4.4 to 16 percent for SC and from 39 to 151 percent for SAR. In comparison, if the streamflow was 600 ft 3 /s, the projected increases would range from 2.2 to 8.4 percent for SC and from 21 to 79 percent for SAR. This analysis of potential water-quality effects on the SC and SAR of the Tongue River in the study area assumes that the quantity and quality of water flowing into the study reach at the time of this study was the same as during the period before CBM development (data from water years 1985-99).

Wyoming;Montana

Occurrence of Uranium and 222Radon in Glacial and Bedrock Aquifers in the Northern United States, 1993-2003

Water-quality data collected from 1,426 wells during 1993-2003 as part of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) program were evaluated to characterize the water quality in glacial and bedrock aquifers of the northern United States. One of the goals of the NAWQA program is to synthesize data from individual studies across the United States to gain regional- and national-scale information about the behavior of contaminants. This study focused on the regional occurrence and distribution of uranium and 222radon in ground water in the glacial aquifer system of the United States as well as in the Cambrian-Ordovician and the New York and New England crystalline aquifer systems that underlie the glacial aquifer system. The occurrence of uranium and 222radon in ground water has long been a concern throughout the United States. In the glacial aquifers, as well as the Cambrian-Ordovician and the New York and New England crystalline aquifer systems of the United States, concentrations of uranium and 222radon were highly variable. High concentrations of uranium and 222radon affect ground water used for drinking water and for agriculture. A combination of information or data on (1) national-scale ground-water regions, (2) regional-scale glacial depositional models, (3) regional-scale geology, and (4) national-scale terrestrial gamma-ray emissions were used to confirm and(or) refine the regions used in the analysis of the water-chemistry data. Significant differences in the occurrence of uranium and 222radon, based primarily on geologic information were observed and used in this report. In general, uranium was highest in the Columbia Plateau glacial, West-Central glacial, and the New York and New England crystalline aquifer groups (75th percentile concentrations of 22.3, 7.7, and 2.9 micrograms per liter (ug/L), respectively). In the Columbia Plateau glacial and the West-Central glacial aquifer groups, more than 10 percent of wells sampled had concentrations of uranium that exceeded the U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Level of 30 ug/L; in the New York and New England crystalline aquifer group, 4 percent exceeded 30 ug/L. Ground-water samples with high concentrations of uranium were commonly linked to geologic sources rich in uranium. In eight of nine aquifer groups defined for this study, concentrations of uranium correlated significantly with concentrations of sulfate in ground water (Spearman's rho = 0.20 to 0.56; p < 0.05). In the Columbia Plateau, glacial aquifers were derived in part from basaltic lava flows, some felsic volcanic rocks, and some paleo-lake bed materials that may be rich in uranium. In the Columbia Plateau and West-Central glacial aquifer groups, uranium correlated with total dissolved solids, bicarbonate, boron, lithium, selenium, and strontium. In the West-Central glacial aquifer group, rocks such as Cretaceous marine shales, which are abundant in uranium, probably contribute to the high concentrations in ground water; in the southern part of this group, which extends into Nebraska, the glacial or glacial-related sediment may be interbedded with uranium-rich materials that originated to the north and west and in the Rocky Mountains. In New England, crystalline bedrock that is granitic, such as two-mica granites, as well as other high-grade metamorphic rocks, has abundant uranium that is soluble in the predominantly oxic to sub-oxic geochemical conditions. This appears to contribute to high uranium concentrations in ground water. The highest 222radon concentrations were present in samples from wells completed in the New York and New England crystalline aquifer group; the median value (2,122 picocurries per liter (pCi/L)) was about 10 times the median values of all other aquifer groups. More than 25 percent of the samples from the New York and New England crystalline aquifer group wells had 222radon concentrations that exceeded the USEPA Alternative

Scientific Investigations Report

Floods of 2011 in New York

Record rainfall combined with above-average temperatures and substantial spring snowmelt resulted in record flooding throughout New York during 2011. Rainfall totals in eastern New York were the greatest since 1895 and as much as 60 percent above the long-term average within the Catskill Mountains area and the Susquehanna River Basin. This report documents the three largest storms and resultant flooding during the year: (1) spring storm during April and May, (2) Tropical Storm Irene during August, and (3) remnants of Tropical Storm Lee during September. According to the Federal Emergency Management Agency (FEMA), the cost of these three storms exceeded $1 billion in Federal disaster assistance. A warm and wet spring in northern New York resulted in record flooding at 21 U.S. Geological Survey (USGS) active streamgages during late April to early May with the annual exceedance probabilities (AEPs) of 11 peak discharges equaling or exceeding 1 percent. Nearly 5 inches of rain during late April combined with a rapidly melting snowpack caused widespread flooding throughout northern New York, resulting in many road closures, millions of dollars in damages, and 23 counties declared disaster areas and eligible for public assistance. On May 6, Lake Champlain recorded its highest lake level in over 140 years. Hurricane Irene entered New York State on August 28 as a tropical storm and traveled up the eastern corridor of the State, leaving a path of destruction and damage never seen in many parts of New York. Thirty-one counties in New York were declared disaster areas with damages of over $1.3 billion dollars and 10 reported deaths. Storm rainfall exceeded 18 inches in the Catskill Mountains area of southeastern New York with many other areas of eastern New York receiving over 7 inches. Catastrophic flooding resulted from the extreme rainfall in many locations, including Schoharie Creek and its tributaries, the eastern Delaware River Basin, the Ausable and Bouquet River Basins in northeastern New York, and several other stream basins throughout southeastern New York. Downstream reaches of the Mohawk River also had substantial flooding. Sixty-two USGS streamgages throughout eastern New York documented record high stream flows and elevations with AEPs of 25 peak discharges equaling or exceeding 1 percent. The USGS streamgage for the Schoharie Creek at Prattsville recorded its greatest peak discharge in 109 years of record at 120,000 cubic feet per second (greater than the 0.2-percent AEP discharge) on August 28. The peak water-surface elevation at the streamgage in Prattsville was 5 feet higher than its previous record in 1996. USGS personnel surveyed 184 high-water marks (HWMs) at 30 locations along an 84-mile reach of Schoharie Creek and compared the elevations to those published by FEMA for the 10-, 2-, 1-, and 0.2-percent AEP floods. Elevations in the lower reaches of the basin exceeded published elevations for the 0.2-percent AEP flood. Remnants of Tropical Storm Lee brought a third major storm to New York in September 2011. Moisture from Lee began moving into New York on September 7 and intensified over the already saturated Susquehanna River Basin. Most of the rain fell on September 8 with storm totals nearing 13 inches in some areas (12.73 inches at Apalachin in Tioga County). Major disaster declarations were issued for 15 counties in and around central New York, making them eligible for individual or public assistance. Ten USGS streamgages within the Susquehanna River Basin documented record-high stream discharges and elevations on September 8, and all were greater than the 1-percent AEP discharge. USGS personnel surveyed 20 HWMs at 18 locations along a 114- mile reach of the Susquehanna River and compared the elevations to those published by FEMA for the 10-, 2-, 1-, and 0.2-percent AEP floods. Several of the surveyed HWMs exceeded published elevations for the 0.2-percent AEP flood.

New York

Volcano and earthquake monitoring plan for the Yellowstone Caldera system, 2022–2032

Executive Summary The Yellowstone Volcano Observatory (YVO) is a consortium of nine Federal, State, and academic agencies that: (1) provides timely monitoring and hazards assessment of volcanic, hydrothermal, and earthquake activity in and around Yellowstone National Park, and (2) conducts research to develop new approaches to volcano monitoring and better understand volcanic activity in the Yellowstone region and elsewhere. The U.S. Geological Survey (USGS) arm of YVO is also responsible for monitoring and reporting on volcanic activity in the Intermountain West of the United States. The previous YVO monitoring plan for the Yellowstone region spanned 2006–2015 and focused on strengthening the region-wide coverage, or backbone, of monitoring systems (Yellowstone Volcano Observatory, 2006). The goals of that plan have largely been achieved thanks to significant investments in instrumentation and infrastructure, especially by the National Science Foundation EarthScope Plate Boundary Observatory (now known as the Network Of The Americas, or NOTA) and the American Reinvestment and Recovery Act. This revision of the monitoring plan, covering 2022–2032, builds upon these improvements to monitoring systems in the Yellowstone region while also accounting for new insights into the dynamics of the area’s seismic, volcanic, and hydrothermal activity. These additional improvements are designed to fill gaps in the monitoring network and to better understand and track hazards associated with hydrothermal processes. These improvements include: Conversion of remaining analog seismic stations to digital, Addition of Global Positioning System (GPS) stations in the vicinity of Norris Geyser Basin and other areas where changes in deformation rate and style have been observed, Implementation of continuous gas monitoring in several areas of Yellowstone National Park, and Improvements to lake, meteorological, and hydrological monitoring to better track hydrothermal activity, including that occurring on lake bottoms, and to aid in understanding of whether such activity might be influenced by external forces, like environmental conditions. The 2022–2032 monitoring plan for the Yellowstone volcanic system also proposes to improve monitoring of hydrothermal areas to better understand these dynamic systems and their associated hazards. To date, only a single seismometer has been placed within one of Yellowstone National Park’s geyser basins because seismic noise associated with boiling water can hinder interpretation of overall seismic and magmatic activity, but this concern has been mitigated by improvements to backbone monitoring. Deployment of geophysical, geochemical, hydrological, and geological monitoring instruments in geyser basins will be accompanied by campaigns to measure gas and water chemistry and flux, as well as aerial and satellite surveys of gas and thermal emissions. Close collaboration between YVO member institutions and other research agencies is needed to achieve these monitoring goals and to use the derived data to advance understanding of how Yellowstone Caldera and similar volcanic systems work. At the same time, attention must be paid to minimize the impact of monitoring efforts and infrastructure on the environment. YVO thus commits to serving as stewards of the natural, cultural, and historical resources in and around Yellowstone National Park while maximizing scientific gain for the betterment of society.

Wyoming