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At least 289 records · Page 16Linked to original sources

USGS2012

Effects of groundwater pumping in the lower Apalachicola-Chattahoochee-Flint River basin

USGS developed a groundwater-flow model of the Upper Floridan aquifer in lower Apalachicola-Chattahoochee-Flint River basin in southwest Georgia and adjacent parts of Alabama and Florida to determine the effect of agricultural groundwater pumping on aquifer/stream flow within the basin. Aquifer/stream flow is the sum of groundwater outflow to and inflow from streams, and is an important consideration for water managers in the development of water-allocation and operating plans. Specifically, the model was used to evaluate how agricultural pumping relates to 7Q10 low streamflow, a statistical low flow indicative of drought conditions that would occur during seven consecutive days, on average, once every 10 years. Argus ONETM, a software package that combines a geographic information system (GIS) and numerical modeling in an Open Numerical Environment, facilitated the design of a detailed finite-element mesh to represent the complex geometry of the stream system in the lower basin as a groundwater-model boundary. To determine the effects on aquifer/stream flow of pumping at different locations within the model area, a pumping rate equivalent to a typical center-pivot irrigation system (50,000 ft3/d) was applied individually at each of the 18,951 model nodes in repeated steady-state simulations that were compared to a base case representing drought conditions during October 1999. Effects of nodal pumping on aquifer/stream flow and other boundary flows, as compared with the base-case simulation, were computed and stored in a response matrix. Queries to the response matrix were designed to determine the sensitivity of targeted stream reaches to agricultural pumping. Argus ONE enabled creation of contour plots of query results to illustrate the spatial variation across the model area of simulated aquifer/streamflow reductions, expressed as a percentage of the long-term 7Q10 low streamflow at key USGS gaging stations in the basin. These results would enable water managers to assess the relative impact of agricultural pumping and drought conditions on streamflow throughout the basin, and to develop mitigation strategies to conserve water resources and preserve aquatic habitat.

Alabama, Georgia, Florida↗

USGS2023

A conceptual workflow for projecting future riverine and coastal flood hazards to support the federal flood risk management standard

In 2021, the reinstatement of the Federal Flood Risk Management Standard (FFRMS) required federally funded projects to recognize potential increases in flood hazards over their service lives due to climate change or local anthropogenic perturbations. Recognizing that the state of the science had advanced since the implementation guidelines for this standard were published in 2015 (WRC, 2015, Appendix H), an interagency state-of-the-science review committee conceptualized a workflow to guide the mapping and risk communication of projected future flood hazards in both riverine and coastal settings. This five-element workflow connects climate, hydrologic, and hydraulic models, incorporates land and water management impacts and ongoing geomorphic changes, and can be tailored to the unique nature of different agency needs and resources. These conceptual workflows also provide a basis for a Climate-Informed Science Approach (CISA) implementation roadmap that identifies incremental steps for addressing the research and data gaps elucidated in our review. Many of these incremental steps present opportunities for interagency collaboration that would facilitate the rollout of the FFRMS in diverse riverine and coastal settings of the United States. We conduct case-study thought experiments to evaluate the implementation of the riverine and coastal workflows at three different locations in the United States: central Indiana, Galveston, Texas, and a small coastal community in western Alaska (Shaktoolik). Our thought experiments consider different project horizons, data availability, failure consequences, technical training requirements, and computational resources.

Conference Paper↗

USGS2015

Hydraulic fracturing water use variability in the United States and potential environmental implications

Until now, up-to-date, comprehensive, spatial, national-scale data on hydraulic fracturing water volumes have been lacking. Water volumes used (injected) to hydraulically fracture over 263,859 oil and gas wells drilled between 2000 and 2014 were compiled and used to create the first U.S. map of hydraulic fracturing water use. Although median annual volumes of 15,275 m3 and 19,425 m3 of water per well was used to hydraulically fracture individual horizontal oil and gas wells, respectively, in 2014, about 42% of wells were actually either vertical or directional, which required less than 2600 m3 water per well. The highest average hydraulic fracturing water usage (10,000−36,620 m3 per well) in watersheds across the United States generally correlated with shale-gas areas (versus coalbed methane, tight oil, or tight gas) where the greatest proportion of hydraulically fractured wells were horizontally drilled, reflecting that the natural reservoir properties influence water use. This analysis also demonstrates that many oil and gas resources within a given basin are developed using a mix of horizontal, vertical, and some directional wells, explaining why large volume hydraulic fracturing water usage is not widespread. This spatial variability in hydraulic fracturing water use relates to the potential for environmental impacts such as water availability, water quality, wastewater disposal, and possible wastewater injection-induced earthquakes.

Water Resources Research↗

USGS2008

Deep drilling into the Chesapeake Bay impact structure

Samples from a 1.76-kilometer-deep corehole drilled near the center of the late Eocene Chesapeake Bay impact structure (Virginia, USA) reveal its geologic, hydrologic, and biologic history. We conducted stratigraphic and petrologic analyses of the cores to elucidate the timing and results of impact-melt creation and distribution, transient-cavity collapse, and ocean-water resurge. Comparison of post-impact sedimentary sequences inside and outside the structure indicates that compaction of the crater fill influenced long-term sedimentation patterns in the mid-Atlantic region. Salty connate water of the target remains in the crater fill today, where it poses a potential threat to the regional groundwater resource. Observed depth variations in microbial abundance indicate a complex history of impact-related thermal sterilization and habitat modification, and subsequent post-impact repopulation.

Science↗

USGS2025

Streamflow as a stressor: Disentangling hydrology and water quality impacts to characterize flow-ecology relationships for two stream assemblages across two southeastern landscapes

Disassociating the independent effects of flow and water quality on the ecology of flowing waters is an overarching goal in water resource science needed to improve the efficacy of watershed management. However, the interrelatedness of these gradients and their subsequent alteration due to land use change has constrained progress made on this front. The objective of this study was to use benthic macroinvertebrate and fish assemblage data to characterize flow-ecology relationships that were unchanged by water quality impacts across two southeastern landscapes in the USA to help detect ecological change driven by flow alteration. General linear latent models were used to identify taxa that were responsive to high or low flow metrics and water quality gradients. Bayesian hierarchical generalized additive models were then developed using these indicator taxa and three biological metrics to identify flow-specific relationships that were unaffected by water quality impacts. Three low flow-specific relationships were identified, illustrating how potential agricultural or urban impacts to hydrology reduced stream biological health. Importantly, flow-ecology relationships developed using indicator taxa in this study effectively captured hydrology-specific impacts while biological metrics typical of state monitoring and assessment programs did not. Therefore, developing flow-specific biological metrics is a critical step when developing management strategies targeting flow alteration. Implementing standardized frameworks such as the one characterized here can limit contradictory findings and improve streamflow enhancement and restoration project efficacy. These low flow-specific relationships will enhance managers' capacity to develop environmental flow standards, monitor their success, and better understand urban and agricultural impacts on stream assemblages.

Alabama↗

USGS1987

Hydrologic monitoring of selected streams in coal fields of central and southern Utah — Summary of data collected, August 1978-September 1984

The U.S. Geological Survey conducted a coal-hydrology monitoring program in coal-field areas of central and southern Utah during August 1978-September 1984 to determine possible hydrologic impacts of future mining and to provide a better understanding of the hydrologic systems of the coal resource areas monitored. Data were collected at 19 gaging stations--18 stations in the Price, San Rafael, and Dirty Devil River basins, and 1 in the Kanab Creek Basin. Streamflow data were collected continuously at 11 stations and seasonally at 5 stations. At the other three stations streamflow data were collected continuously during the 1979 water year and then seasonally for the rest of their periods of record. Types of data collected at each station included quantity and quality of streamflow; suspended sediment concentrations; and descriptions of stream bottom sediments, benthic invertebrate, and phytoplankton samples. Also, base flow measurements were made annually upstream from 12 of the gaging stations. Stream bottom sediment sampled at nearly all the monitoring sites contained small to moderate quantities of coal, which may be attributed chiefly to pre-monitoring mining. Streamflow sampled at several sites contained large concentrations of sulfate and dissolved solids. Also, concentrations of various trace elements at 10 stations, and phenols at 18 stations, exceeded the criteria of the EPA for drinking water. This may be attributed to contemporary (water years 1979-84) mine drainage activities. The data collected during the complete water years (1979-84) of monitoring do provide a better understanding of the hydrologic systems of the coal field areas monitored. The data also provide a definite base by which to evaluate hydrologic impacts of continued or increased coal mining in those areas. (Author 's abstract)

Utah↗

USGS1985

Effects of flood control alternatives on fish and wildlife resources of the Malheur-Harney lakes basin

Malheur Lake is the largest freshwater marsh in the western contiguous United States and is one of the main management units of the Malheur National Wildlife Refuge in southeastern Oregon. The marsh provides excellent waterfowl production habitat as well as vital migration habitats for birds in the Pacific flyway. Water shortages have typically been a problem in this semiarid area; however, record snowfalls and cool summers have recently caused Malheur Lake to rise to its highest level in recorded history. This has resulted in the loss of approximately 57,000 acres of important wildlife habitat as well as extensive flooding of local ranches, roads, and railroad lines. Because of the importance of the Refuge, any water management plan for the Malheur-Harney Lakes Basin needs to consider the impact of management alternatives on the hydrology of Malheur Lake. The facilitated modeling workshop described in this report was conducted January 14-18, 1985, under the joint sponsorship of the Portland Ecological Services Field Office and the Malheur National Wildlife Refuge, Region 1, U.S. Fish and Wildlife Service (FWS). The Portland Field Office is responsible for FWS reporting requirements on Federal water resource projects while the Refuge staff has management responsibility for much of the land affected by high water levels in the Malheur-Harney Lakes Basin. The primary objective of the workshop was to begin gathering and analyzing information concerning potential fish and wildlife impacts, needs, and opportunities associated with proposed U.S. Army Corps of Engineers (COE) flood control alternatives for Malheur Lake. The workshop was structured around the formulation of a computer model that would simulate the hydrologic effects of the various alternatives and any concommitant changes in vegetation communities and wildlife use patterns. The simulation model is composed of three connected submodels. The Hydrology submodel calculates changes in lake volume, elevation, and surface area, as well as changes in water quality, that result from the proposed water management projects (upstream storage, upstream diversions, drainage canals) and the no action alternative. The Vegetation submodel determines associated changes in the areal extent of wetland and upland vegetation communities. Finally, the Wildlife submodel calculates indices of abundance or habitat suitability for colonial nesting birds (great egret, double-crested cormorant, white-faced ibis), greater sandhill crane, diving ducks, tundra swan, dabbling ducks, and Canada goose based on hydrologic and vegetation conditions. The model represents the Malheur-Harney Lakes Basin, but provides water quantity and quality indicators associated with additional flows that might occur in the Malheur River Basin. Several management scenarios, representing various flood control alternatives and assumptions concerning future runoff, were run to analyze model behavior. Scenario results are not intended as an analysis of all potential management actions or assumptions concerning future runoff. Rather, they demonstrate the type of analysis that could be conducted if the model was sufficiently refined and tested. Early in a model development project, the process of building the model is usually of greater benefit than the model itself. The model building process stimulates interaction among agencies, assists in integrating existing information, and helps identify research needs. These benefits usually accrue even in the absence of real predictive power in the resulting model. This workshop initiated interaction among the primary State and Federal resource and development agencies in a nonadversarial forum. The exchange of information and expertise among agencies provided the FWS with the best information currently available for use in the Planning Aid Letter it will develop at the Reconnaissance state of the COE study. If the COE subsequently initiates a Feasability Study, this information will be refined further and will aid the FWS in preparing its Coordination Act Report on any flood control alternative proposed by the COE. The model building and testing process also helped identify model limitations and more general information needs that should be evaluated for further study prior to preparation of an FWS Coordination Act Report. Major needs associated with the Hydrology submodel include a more detailed representation of hydrologic units (separately consider Harney Lake, Mud Lake, and Malheur Lake or the three hydrological units within Malheur Lake, rather than a combined lake system) and explicitly representation of groundwater storage and discharge in water budget calculations. A better representation of the hydrological units will require more detailed topographic data for the basin, capacity-elevation and elevation-surface area curves for each unit, and better water flow data between the units. Additional water quality parameters and constraints on proposed canal operation due to conditions in the Malheur River might also be added. Key Vegetation submodel needs include fine-tuning existing vegetation relationships in the model and adding relationships to address the influence of historical conditions on vegetation development, effects of very rapid changes in lake level, effects of wildlife populations (e.g., carp, muskrat), responses of vegetation to habitat management actions (e.g, haying, grazing, burning), and better representation of sago pondweed dynamics. A complementary geographic information system might also be developed for spatial analyses. Major needs that should be evaluated for the Wildlife submodel include addition of other wildlife species that have important effects on habitat on the Refuge (e.g., carp, muskrat) and consideration of additional life-cycle requisites and controlling variable for species presently in the model. Some of these limitations could perhaps be overcome if historical data on habitat conditions were developed to use with historical data on wildlife populations.

Oregon↗

USGS2005

Impact of anthropogenic development on coastal ground-water hydrology in southeastern Florida, 1900-2000

Southeastern Florida is an area that has been subject to widely conflicting anthropogenic stress to the Everglades and coastal ecosystems. This stress is a direct consequence of the 20th century economic competition for limited land and water resources needed to satisfy agricultural development and its expansion, its displacement by burgeoning urban development, and the accompanying growth of the limestone mining industry. The development of a highly controlled water-management system designed to reclaim land for urban and agricultural development has severely impacted the extent, character, and vitality of the historic Everglades and coastal ecosystems. An extensive conveyance system of canals, levees, impoundments, surface- water control structures, and numerous municipal well fields are used to sustain the present-day Everglades hydrologic system, prevent overland flow from moving eastward and flooding urban and agricultural areas, maintain water levels to prevent saltwater intrusion, and provide an adequate water supply. Extractive mining activities expanded considerably in the latter part of the 20th century, largely in response to urban construction needs. Much of the present-day urban-agricultural corridor of southeastern Florida lies within an area that is no more than 15 feet above NGVD 1929 and formerly characterized by freshwater marsh, upland, and saline coastal wetland ecosystems. Miami- Dade, Broward, and Palm Beach Counties have experienced explosive population growth, increasing from less than 4,000 inhabitants in 1900 to more than 5 million in 2000. Ground-water use, the principal source of municipal supply, has increased from about 65 Mgal/d (million gallons per day) obtained from 3 well fields in 1930 to more than 770 Mgal/d obtained from 65 well fields in 1995. Water use for agricultural supply increased from 505 Mgal/d in 1953 to nearly 1,150 Mgal/d in 1988, but has since declined to 764 Mgal/d in 1995, partly as a result of displacement of the agricultural industry by urban growth. Present-day agricultural supplies are obtained largely from surface-water sources in Palm Beach County and ground-water sources in Miami-Dade County, whereas Broward County agricultural growers have been largely displaced. The construction of a complex canal drainage system and large well fields has substantially altered the surface- and ground-water hydrologic systems. The drainage system constructed between 1910 and 1928 mostly failed to transport flood flows, however, and exacerbated periods of low rainfall and drought by overdraining the surficial aquifer system. Following completion of the 1930s Hoover Dike levee system that was designed to reduce Lake Okeechobee flood flows, the Central and Southern Florida Flood Control Project initiated the restructure of the existing conveyance system in 1948 through canal expansion, construction of protective levees and control structures, and greater management of ground-water levels in the surficial aquifer system. Gated canal control structures discharge excess surface water during the wet season and remain closed during the dry season to induce recharge by canal seepage and well withdrawals. Management of surface water through canal systems has successfully maintained lower ground-water levels inland to curb urban and agricultural flooding, and has been used to increase ground-water levels near the coast to impede saltwater intrusion. Coastal discharge, however, appears to have declined, due in part to water being rerouted to secondary canals, and to induced recharge to the surficial aquifer system by large municipal withdrawals. Southeastern Florida is underlain by Holocene- to Tertiary-age karstic limestone deposits that form (in descending order): a highly prolific surficial aquifer system, a poorly permeable intermediate confining system, and a permeable Floridan aquifer system. Prior to construction of a complex drainage netwo

Florida↗

USGS2024

Effects of 2D hydrodynamic model resolution on habitat estimates for rearing Coho Salmon in contrasting channel forms

Estimating the impacts of water allocation decisions on fish populations and habitat availability is an important part of environmental flow assessments, especially in locations where water resources are limited. Two-dimensional hydrodynamic models (2DHMs) are commonly coupled with biological models to estimate fish habitat quality, area, and capacity across a range of proposed streamflows. Increasingly, resource managers are relying on landscape-scale model domains with coarse model resolutions to maintain feasible computational loads, but this may affect habitat estimates if the mesh element size of the model exceeds the spatial scale relevant to the organism. We investigated how coarsening the resolution of a 2DHM influences the area and spatial distribution of estimated Coho Salmon ( Oncorhynchus kisutch ) fry habitats. We used an interpolation scheme that upscaled mesh elements from a high-resolution (0.25 m 2 ) 2DHM to quantify and visualize the effects of 2DHM resolution on estimates of Coho Salmon fry habitat for two contrasting channel morphologies and across a broad range of streamflows. Estimates of Coho Salmon fry habitat at increasingly coarser resolutions led to 20%–50% reductions in weighted usable habitat area (WUA) across several streamflow scenarios for a complex channel type, but did not impact estimates in a confined, flume-like channel. Additionally, flow-to-habitat area relationships were not congruent at a given streamflow when resolution coarsened. Along with almost 500% more high-quality habitat area estimated in the complex channel type over the confined, discrepancies in habitat area increased with higher flows in areas defined as optimal for rearing Coho Salmon fry. Considering that complex channel types contain critical habitat for Coho Salmon fry, this study suggests coarse 2DHM resolutions may exclude important wetted edge and off-channel habitats from environmental flow assessments.

California↗

USGS2004

Direction of ground-water flow in the surficial aquifer in the vicinity of impact areas G-10 and K-2, Camp Lejeune Marine Corps Base, North Carolina, 2004

Marine Corps Base Camp Lejeune is located in Onslow County in the North Carolina Coastal Plain. In support of North Carolina Department of Environment and Natural Resource requirements, Camp Lejeune is developing a site closure plan for two Resource Conservation and Recovery Act (RCRA) regulated open burn/open detonation (OB/OD) facilities located within Impact Area K-2 and Impact Area G-10, respectively. Both Impact Areas are used for training activities involving live artillery fire. The two OB/OD facilities are used to treat RCRA regulated waste munitions. To provide Base officials with information needed for assessing the quality of ground water at these sites, hydrologic data were used to characterize groundwater flow directions and hydraulic gradients in the surficial aquifer underlying the Impact Areas. Water-level data in the unconfined surficial aquifer and potentiometric head data in the underlying Castle Hayne aquifer were compiled from existing and newly drilled wells. Water-table contour maps were developed for Impact Areas K-2 and G-10 to examine the direction of ground-water flow in the surficial aquifer. The primary directions of ground-water flow beneath K-2 are southward and eastward toward discharge zones along the New River and its tributaries. Beneath interior areas of G-10, water in the surficial aquifer flows outward in all directions toward discharge zones along local streams that drain westward to the New River or to streams that drain southward and eastward to the Intracoastal Waterway and the Atlantic Ocean. Long-term water-level data for the period October 1994 through September 2004 at selected Camp Lejeune well sites were used to examine trends in ground-water levels and vertical hydraulic gradients between the surficial and Castle Hayne aquifers. Evaluation of water-level data for three wells in the surficial aquifer indicated no significant trends for this period of record. The apparent water-level declines in two of the three Castle Hayne wells examined are likely the result of local pumping of the Castle Hayne aquifer. Vertical hydraulic gradients determined for two well cluster sites indicate a downward flow of water from the surficial aquifer into the underlying Castle Hayne aquifer.

Scientific Investigations Report↗

USGS2009

Social, political, and institutional setting: Water management problems of the Rio Grande

This paper discusses various water management issues facing federal, state, and local agencies charged with managing the water resources of the Rio Grande River Basin and its major tributaries. The Rio Grande - 3,058 km (=1,900 mi) long - is the fourth longest river in the United States. The river's basin is 870,236 km 2 (=336,000 mi 2 ) and for roughly two-thirds of its length it forms the United States-Mexican border. It is a major recreational resource providing world class trout fishing near its headwaters in Colorado's San Juan Mountains and shoreline, angling, and boating opportunities near the Colorado-New Mexico border. The Rio Grande is the principal tourist attraction of Big Bend National Park and flows through downtown Albuquerque and El Paso. Many reaches are wide and broad, but almost all are relatively shallow and not navigable by commercial ships. Nevertheless, it is one of the most important renewable water resources of the southwestern United States and North America. The issue of the "manageability" of the river in the face of social forces and disparate administrative jurisdictions that adversely impact Rio Grande flows is a thread linking various sections of the paper together. The length of the river; the fact that major reaches lie in Colorado, New Mexico, and Texas; and its unique role as an international boundary pose complex management problems. The allocation status quo formed by the complex nexus of existing river laws make it difficult to reshape Rio Grande management. ?? 2009 ASCE.

Journal of Water Resources Planning and Management↗

USGS2016

Hydrologic restoration in a dynamic subtropical mangrove-to-marsh ecotone

Extensive hydrologic modifications in coastal regions across the world have occurred to support infrastructure development, altering the function of many coastal wetlands. Wetland restoration success is dependent on the existence of hydrologic regimes that support development of appropriate soils and the growth and persistence of wetland vegetation. In Florida, United States, the Comprehensive Everglades Restoration Program (CERP) seeks to restore, protect, and preserve water resources of the greater Everglades region. Herein we describe vegetation dynamics in a mangrove-to-marsh ecotone within the impact area of a CERP hydrologic restoration project currently under development. Vegetation communities are also described for a similar area outside the project area. We found that vegetation shifts within the impact area occurred over a 7-year period; cover of herbaceous species varied by location, and an 88% increase in the total number of mangrove seedlings was documented. We attribute these shifts to the existing modified hydrologic regime, which is characterized by a low volume of freshwater sheet flow compared with historical conditions (i.e. before modification), as well as increased tidal influence. We also identified a significant trend of decreasing soil surface elevation at the impact area. The CERP restoration project is designed to increase freshwater sheet flow to the impact area. Information from our study characterizing existing vegetation dynamics prior to implementation of the restoration project is required to allow documentation of long-term project effects on plant community composition and structure within a framework of background variation, thereby allowing assessment of the project's success in restoring critical ecosystem functions.

Florida↗

USGS2023

Hypoxia and anoxia tolerance in diploid and triploid eastern oysters at high temperature

Increasing reliance on the use of triploid oysters to support aquaculture production relies on their generally superior growth rate and meat quality over that of diploid oysters. Reports of elevated triploid mortality have generated questions about potential trade-offs between growth and tolerance to environmental stressors. These questions are particularly relevant as climate change, coastal activities, and river management impact water salinity, temperature, nutrients, pH, and oxygen levels within key estuarine oyster growing areas. In particular, the co-occurrence of warm water temperatures and low dissolved oxygen concentration (DO) events are increasingly reported in estuaries, with potentially lethal impacts on sessile, oyster resources. To investigate potential differences in DO tolerance, diploid and triploid market-sized or seed oysters were exposed to continuous normoxia (DO > 5.0 mg L –1 ), hypoxia (DO < 2.0 mg L –1 ), and anoxia (DO < 0.5 mg L –1 ) at 28°C and their mortalities were monitored. The hemolymph of the market-sized oysters was collected to measure cellular and biochemical changes in response to hypoxia and anoxia, whereas their valve movements were also measured. In general, about half of market-sized oysters died within about 1 wk under anoxia (LT 50 : 5.7–8.9 days) and within about 2 wk under hypoxia (LT 50 : 11.9–19.4 days) with diploid oysters tending to die faster than triploid oysters. Seed oysters took longer to die than market-sized oysters under both anoxia (LT 50 : 9.5–12.1 days) and hypoxia (LT 50 : 21.8–25.0 days) with diploid oysters (LT 50 : 9.5–11.8 days) dying slightly faster than triploid oysters (LT 50 : 11.8–12.1 days) under anoxia. Hemolymph pH decreased and plasma calcium and glutathione concentrations increased with decreasing DO, with values under anoxia being different than those under normoxia. Hemocyte density was also lower under anoxia than under either normoxia or hypoxia. Overall, few differences in physiological responses to hypoxia and anoxia were found between diploid and triploid oysters suggesting that ploidy (2N versus 3N) had limited effect on the tolerance and response of eastern oysters to low DO.

Journal of Shellfish Research↗

USGS2023

Prediction of the probability of elevated nitrate concentrations at groundwater depths used for drinking-water supply in the Puget Sound basin, Washington, 2004–19

The Puget Sound basin encompasses the 13,700-square-mile area that drains to the Puget Sound and the adjacent marine waters of Washington State. Well more than 4 million people live within the basin, with numbers continuing to increase, who rely on the basin’s natural resources including groundwater. The Puget Sound Partnership was created by a Washington State statute to implement a science-based recovery of the Puget Sound to help address impacts to these resources. As part of the recovery, the partnership developed the Puget Sound Vital Signs as measures of ecosystem health that guide the assessment of progress toward Puget Sound recovery goals. The Puget Sound Partnership Leadership Council adopted a Drinking Water Vital Sign associated with human health and quality of life, recognizing certain indicators as integral to the sustainability of Puget Sound recovery efforts. One such Vital Sign indicator was the vulnerability of groundwater throughout the aquifers of the Puget Sound basin to elevated nitrate concentrations as defined by the probability of exceeding 2 milligrams/liter (mg/L) at a specific location and well depth. The U.S. Geological Survey (USGS) led the effort to characterize groundwater vulnerability. For this study, groundwater vulnerability refers to a probability with which a contaminant applied at or near the land surface can migrate to the aquifer of interest for a given set of land-use practices. Nitrate concentration data were selected for evaluation because elevated nitrate concentrations are typically caused by anthropogenic activities and have been associated with deleterious impacts on human health. To identify groundwater vulnerability to elevated nitrate concentrations, logistic regression was used to relate anthropogenic (human associated) and natural variables to the occurrence of elevated nitrate concentrations in untreated groundwater from large public water supply system wells found within the Washington State Department of Health Sentry database. Variables that were analyzed included well depth, soil hydraulic conductivity, precipitation, population density, fertilizer application amounts, and land-use types. Statistically significant models that predicted the probabilities of groundwater nitrate concentrations greater than 2 mg/L based on the predictor variables were created for the time periods 2000–04, 2005–09, 2010–14, and 2015–19. For all time periods, well depth and a measure of the abundance of urban and agricultural land over or near the well consistently helped explain the vulnerability of the well to elevated nitrate concentrations defined as a probability of exceeding 2 mg/L of nitrate. Precipitation and (or) soil hydraulic conductivity were also important predictor variables in the models. The models for each time period were used to create maps of groundwater vulnerability at 150- and 300-foot depths throughout the Puget Sound basin. As expected, the most vulnerable locations were associated with shallower well depths and increased agriculture and urban land cover. Across all four time periods, groundwater vulnerability throughout the Puget Sound was low, with probabilities of exceeding 2 mg/L concentrations of nitrate at depths at 150 and 300 feet typically less than 50 percent. Results also found a slight decrease in probabilities of elevated nitrate concentrations throughout the basin over time. More specifically, additional statistical tests found that groundwater with probabilities of less than about 60 percent declined from 2000 to 2019 and represented more than 75 percent of the modeled Puget Sound basin aquifer. Wells with greater than 60 percent probability increased over the same time period but represented only about 25 percent of the aquifer. The maps and statistical analysis presented in the study provide valuable and informative evaluation of the vulnerability of groundwater in the Puget Sound basin to elevated nitrate concentrations. The probability maps do not represent measured nitrate concentrations in groundwater, but rather they present the probability that nitrate concentrations exceed 2 mg/L. The models and predictions from this study are a viable indicator for the Puget Sound Partnership’s Healthy Human Population—Drinking Water Vital Sign. The logistic regression modeling approach presented here benefits water managers by allowing them to assess temporal trends in a range of probabilities, explore vulnerability changes as new regional land cover and anthropogenic data are generated, and distinguish vulnerabilities at different depths within the aquifer.

Washington↗

USGS2007

Benthic habitats and offshore geological resources of Kaloko-Honokohau National Historical Park, Hawai‘i

Kaloko-Honokōhau National Historical Park (KAHO) is one of three National Park lands located along the western coast of the Island of Hawai‘i and the only one to include submerged lands and marine resources within its official boundaries. The park was established in 1978 and is 1,160 acres in size, including 596 acres of marine area. The submerged lands are currently managed by the State of Hawaii, Department of Land and Natural Resources, Division of Aquatic Resources (DLNR-DAR). Marine resources located within KAHO include coral reef and habitat for many marine animals, including the green sea turtle and a variety of fish and invertebrates. In addition, many archeological, cultural, and recreational resources are located within the marine realm of the park. Potential threats and stressors to the modern marine environment include ground-water and surface-water contamination, invasive plants and algae, fishing pressure and use of monofilament gill nets (which can ensnare marine life or become tangled on reefs and be left behind as fishing debris), and visitor use impacts, such as scuba diving and snorkeling. Illegal dumping, oil releases, boat groundings, and other physical damage to reef resources are potential threats from users of the nearby harbor. Special issues of concern for the park include establishing baseline conditions of the offshore resources before the development of adjacent coastal lands. Until this study, only a general knowledge of the distribution of benthic habitats and the characteristics of the offshore region of Kaloko-Honokōhau National Historical Park was available. In 2003, a collaborative project between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program and the National Park Service (NPS) was initiated to develop detailed benthic-habitat classification maps for the marine lands within and adjacent to the park. The intent of this project is to provide baseline maps and a Geographic Information System (GIS) database and description of the biological and geological resources of these marine lands in order to facilitate the management, interpretation, and understanding of park resources. A benthic-habitat classification map was created for the park using existing color aerial photography, Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) bathymetric data, georeferenced underwater video, and still photography. Individual habitat polygons were classified using five basic attributes: (1) major structure or substrate, (2) dominant structure, (3) major biologic cover on the substrate, (4) percentage of major biological cover, and (5) geographic zone. Additional information regarding geology, morphology, and coral species were also noted. Marine resources located within KAHO include coral reef and habitat for many marine animals, including the green sea turtle and a variety of fish and invertebrates. In addition, many archeological, cultural, and recreational resources are located within the marine realm of the park. Potential threats and stressors to the modern marine environment include ground-water and surface-water contamination, invasive plants and algae, fishing pressure and use of monofilament gill nets (which can ensnare marine life or become tangled on reefs and be left behind as fishing debris), and visitor use impacts, such as scuba diving and snorkeling. Illegal dumping, oil releases, boat groundings, and other physical damage to reef resources are potential threats from users of the nearby harbor. Special issues of concern for the park include establishing baseline conditions of the offshore resources before the development of adjacent coastal lands. Until this study, only a general knowledge of the distribution of benthic habitats and the characteristics of the offshore region of Kaloko-Honokōhau National Historical Park was available. In 2003, a collaborative project between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program and the National Park Service (NPS) was initiated to develop detailed benthic-habitat classification maps for the marine lands within and adjacent to the park. The intent of this project is to provide baseline maps and a Geographic Information System (GIS) database and description of the biological and geological resources of these marine lands in order to facilitate the management, interpretation, and understanding of park resources. A benthic-habitat classification map was created for the park using existing color aerial photography, Scanning Hydrographic Operational Airborne Lidar Survey (SHOALS) bathymetric data, georeferenced underwater video, and still photography. Individual habitat polygons were classified using five basic attributes: (1) major structure or substrate, (2) dominant structure, (3) major biologic cover on the substrate, (4) percentage of major biological cover, and (5) geographic zone. Additional information regarding geology, morphology, and coral species were also noted.

Hawai'i↗

USGS2012

A stakeholder project to model water temperature under future climate scenarios in the Satus and Toppenish watersheds of the Yakima River Basinin Washington, USA

The goal of this study was to support an assessment of the potential effects of climate change on select natural, social, and economic resources in the Yakima River Basin. A workshop with local stakeholders highlighted the usefulness of projecting climate change impacts on anadromous steelhead ( Oncorhynchus mykiss) , a fish species of importance to local tribes, fisherman, and conservationists. Stream temperature is an important environmental variable for the freshwater stages of steelhead. For this study, we developed water temperature models for the Satus and Toppenish watersheds, two of the key stronghold areas for steelhead in the Yakima River Basin. We constructed the models with the Stream Network Temperature Model (SNTEMP), a mechanistic approach to simulate water temperature in a stream network. The models were calibrated over the April 15, 2008 to September 30, 2008 period and validated over the April 15, 2009 to September 30, 2009 period using historic measurements of stream temperature and discharge provided by the Yakama Nation Fisheries Resource Management Program. Once validated, the models were run to simulate conditions during the spring and summer seasons over a baseline period (1981–2005) and two future climate scenarios with increased air temperature of 1°C and 2°C. The models simulated daily mean and maximum water temperatures at sites throughout the two watersheds under the baseline and future climate scenarios.

Washington↗

USGS2024

Quantifying aspect-dependent snowpack response to high-elevation wildfire in the southern Rocky Mountains

Increasing wildfire frequency and severity in high-elevation seasonal snow zones presents a considerable water resource management challenge across the western United States (U.S.). Wildfires can affect snowpack accumulation and melt patterns, altering the quantity and timing of runoff. While prior research has shown that wildfire generally increases snow melt rates and advances snow disappearance dates, uncertainties remain regarding variations across complex terrain and the energy balance between burned and unburned areas. Utilizing paired in situ data sources within the 2020 Cameron Peak burn area on the Front Range of Colorado, U.S., during the 2021–2022 winter, we found no significant difference in peak snow water equivalent (SWE) magnitude between burned and unburned areas. However, the burned south aspect reached peak SWE 22 days earlier than burned north. During the ablation period, burned south melt rates were 71% faster than unburned south melt rates, whereas burned north melt rates were 94% faster than unburned north aspects. Snow disappeared 7–11 days earlier in burned areas than unburned areas. Net energy differences at the burned and unburned weather station sites were seasonally variable, the burned area snowpack lost more net energy during the winter, but gained more net energy during the spring. Increased incoming shortwave radiation at the burned site was 6 x more impactful in altering the net shortwave radiation balance than the decline in surface albedo. These findings emphasize the need for post-wildfire water resource planning that accounts for aspect-dependent differences in energy and mass balance to accurately predict snowpack storage and runoff timing.

Colorado↗

USGS2020

Climate and human water use diminish wetland networks supporting continental waterbird migration

Migrating waterbirds moving between upper and lower latitudinal breeding and wintering grounds rely on a limited network of endorheic lakes and wetlands when crossing arid continental interiors. Recent drying of global endorheic water stores raises concerns over deteriorating migratory pathways, yet few studies have considered these effects at the scale of continental flyways. Here, we investigate the resiliency of waterbird migration networks across western North America by reconstructing long-term patterns (1984–2018) of terminal lake and wetland surface water area in 26 endorheic watersheds. Findings were partitioned regionally by snowmelt- and monsoon-driven hydrologies and combined with climate and human water-use data to determine their importance in predicting surface water trends. Nonlinear patterns of lake and wetland drying were apparent along latitudinal flyway gradients. Pervasive surface water declines were prevalent in northern snowmelt watersheds (lakes −27%, wetlands −47%) while largely stable in monsoonal watersheds to the south (lakes −13%, wetlands +8%). Monsoonal watersheds represented a smaller proportion of total lake and wetland area, but their distribution and frequency of change within highly arid regions of the continental flyway increased their value to migratory waterbirds. Irrigated agriculture and increasing evaporative demands were the most important drivers of surface water declines. Underlying agricultural and wetland relationships however were more complex. Approximately 7% of irrigated lands linked to flood irrigation and water storage practices supported 61% of all wetland inundation in snowmelt watersheds. In monsoonal watersheds, small earthen dams, meant to capture surface runoff for livestock watering, were a major component of wetland resources (67%) that supported networks of isolated wetlands surrounding endorheic lakes. Ecological trends and human impacts identified herein underscore the importance of assessing flyway-scale change as our model depictions likely reflect new and emerging bottlenecks to continental migration.

Global Change Biology↗