2015 NGWA Conference on the Upper Great Plains: Alphabetical Content Listing

Agriculture and Groundwater

Russ Dahlgren

Classification of Irrigated and Non-Irrigated Land Using Remote Sensing Techniques: A Case Study in Nebraska

Ruopu Li, Ph.D.
Detailed and spatially explicit information on irrigated and non-irrigated land is critical to reliable estimation of recharge for building numerical groundwater models. Currently, such information is typically difficult and costly to compile, and its accuracy is often subject to considerable uncertainties. To develop a cost-effective land use product, a method integrating pixel-based remote sensing indexes and object-oriented classification is proposed for classifying irrigated and non-irrigated land. The method was tested in a study area in south-central Nebraska, and the results showed that the method can produce reasonable accuracy for irrigated and non-irrigated land classification. The method is expected to be applied in other parts of the state.

Simulating Coupled Reactive Salinity Transport in an Agricultural Groundwater System

Saman Tavakoli
The Lower Arkansas River Valley (LARV) in southeastern Colorado is a key resource for stakeholders in southeastern Colorado due to its valuable agriculture production. Because of a rising water table due to excessive irrigation and canal seepage, mobilization of native salts, and evaporative concentration, much of the soil-aquifer system in the valley has become salinized, thereby negatively impacting crop yield. High groundwater salinity loading to the Arkansas River stream network also impacts downstream areas, with saline river water diverted for application on irrigated fields. The overall aim of this project is to develop a numerical modeling framework capable of simulating the transport of salt ions within the stream-aquifer-soil system, so that current conditions of salinity can be assessed and possible remediation strategies in the region can be explored. Results of simulating the fate and transport of sulfur species (principally sulfate SO4) in a 500 km2 region of the LARV using the UZF-RT3D groundwater reactive transport model indicate that advection-dispersion processes, first-order kinetic reactions, and sources/sinks alone cannot account for the high groundwater SO4 concentrations and loadings to the Arkansas River. Hence, a comprehensive salinity module that can be coupled with the UZF-RT3D model and that accounts for salt ions equilibrium chemistry and precipitation-dissolution processes is being developed. Initial model testing with the nested equilibrium module occurs at the field scale, with model results compared with collected salinity data from a lysimeter site at the Arkansas Valley Research Center in Rocky Ford, Colorado.

What’s So Special About Nitrate? Implications for Water Quality in the Upper Great Plains

Scott Korom, PhD, PE
Ammonia synthesis, an economic means to fix nitrogen from the atmosphere, is arguably the most important technological invention of the 20th century; it allowed large-scale industrial production of explosives and nitrogen fertilizers. After World War II, the focus of nitrogen production switched from explosives to fertilizers. Today, without the large-scale use of N in agriculture, as much as 40% of the world’s population would starve due to protein deficiencies. However, as a consequence of its widespread use, nitrate has been called the most common groundwater contaminant. How does nitrate influence water quality?

On a molar basis, nitrate is only slightly less energetic than oxygen as an oxidant; however, nitrate solubility may be over 10,000 times that of oxygen in equilibrium with the atmosphere. As a result, geologic materials exposed to nitrate in groundwater may be oxidized at unprecedented rates. In this paper, I explore how the interaction of nitrate with minerals may have a profound influence on water quality in the Upper Great Plains and beyond. Examples, both actual and hypothetical, are provided to illustrate how nitrate may influence water quality in agriculture, coal mining, coal-fired power plants, and in-situ uranium leach mining.

Challenges in Assessing the Effects of Oil and Gas Development on Groundwater Quality in the Upper Great Plains

Peter B. McMahon, Ph.D.

Energy, Mining, and Law

Kevin D. Frederick, PG

Assessment of Downhole Membrane-Diffused Hydrogen for Stimulating Uranium Reduction and Immobilization

Lewis Haynes
The most common technology currently used for restoring groundwater at in-situ recovery (ISR) uranium mining sites is reverse osmosis and reinjection of the permeate. However, this practice does not restore the formation to its original reduced state, and in many cases groundwater uranium concentrations are not restored to pre-mining baseline levels. This study was performed to evaluate the effectiveness of introducing dissolved hydrogen into a post-mined formation at an ISR mining site to stimulate reduction and immobilization of residual soluble uranium. The main objectives of this research project were: (1) to develop and optimize a system for minimizing air entrainment during water injection when employing a membrane gas-transfer device for downhole hydrogen infusion; and (2) to assess whether injecting dissolved hydrogen using the membrane gas-transfer device can promote immobilization of dissolved uranium in groundwater to near or below pre-mining concentrations. Approximately 15,000 gallons of groundwater were pumped to the surface and then re-injected into the subsurface while being supplied with dissolved hydrogen using the downhole membrane gas infusion device. The groundwater was pumped back to the surface after several months to evaluate the extent to which dissolved uranium had been removed. Initial results indicate an approximately 80% reduction in soluble uranium concentration was achieved. Microbial analyses indicated a significant increase in iron-reducing bacteria, but less significant increases in sulfate-reducing bacteria. A bromide tracer study was performed concurrently with the hydrogen injection study so that the effective zone of influence of the push-pull test could be estimated, while pump tests were performed before and after the hydrogen injection study so the effect of the injected hydrogen on the formation permeability could also be assessed.

Available Groundwater Determination Technical Memoranda for Wyoming River Basin Plans

Karl Taboga, M.S., P.G.
From 2010–2014, the Wyoming State Geological Survey (WSGS) and the U.S. Geological Survey prepared extensive groundwater availability memoranda for five major river basins in Wyoming. The memoranda, developed for inclusion in Wyoming’s State Water Plan, examine groundwater resources for future management in the Green, Wind-Bighorn, Platte, Bear, and Snake-Salt river basins. Extensive analyses of geology, hydrostratigraphy, physical and chemical characteristics, recharge, groundwater uses, and potential sources of contamination are provided for the hydrogeologic units in each river basin. Recent groundwater development projects are reviewed and published studies are listed.

Wyoming’s river basins encompass highly diverse physical, climatologic, and geologic settings. Surface areas of the studied basins range from 2,600 to over 26,000 square miles. Climates vary from semi-arid basin interiors to humid mountains. Laramide structural basins dominate Wyoming’s geology, but the Wyoming Overthrust Belt and Cenozoic volcanic provinces constitute important geologic settings in the western part of the state. Major aquifers consist of Quaternary alluvial deposits, Cretaceous and Tertiary sandstones, and Paleozoic carbonates. Recharge occurs as direct precipitation and streamflow infiltration to bedrock aquifer exposures along basin margins and to basin interior alluvial units.

 The memoranda and associated GIS data can be accessed online, free of charge, at the WSGS website, http://www.wsgs.wyo.gov/Research/Water-Resources/River-Basin-Plans.aspx or at the Wyoming Water Development Commission, http://waterplan.state.wy.us/.

Groundwater Issues for Electric Power Producers Implementing the New Federal Coal Combustion Residuals Rule

Jim Aiken
The new Coal Combustion Residuals (CCR) rule has stringent new groundwater monitoring requirements for existing and future coal ash management facilities. A unique aspect of the rule is its “one size fits all” approach that places prescriptive requirements on facilities across the United States. The rule as written is intended to be self-implementing: there is no regulator unless individual states agree to enforce the requirements of the rule. Instead, enforcement will be through citizen lawsuits under the Resource Conservation and Recovery Act. The EPA has acknowledged that the rules were not developed with attention to the unique groundwater issues faced by professionals in the Upper Great Plains and arid western states. For example, they include prescriptive requirements for the following:
  1. Site characterization and monitoring wells, which in arid states could require drilling multiple wells hundreds of feet or more below the ground surface.
  2. Corrective action or immediate closure if parameters are above MCLs, or in some cases background even though some parameters may be mobilized by ground disturbance unrelated to CCR disposal.

Development of groundwater monitoring strategies will need to address well locations, baseline monitoring, statistical options, parameter specific strategies, integrating groundwater data into ash management decisions, and considerations for retrofit/remediation in light of the new rule.

Facilitated Discussion

Geophysics Equipment Demonstration

Brad Carr, Ph.D.

Poster

Brine Contamination from Oil and Gas Development in the Williston Basin, Montana

Joanna Thamke
Since the 1950s, billions of barrels of brine have been produced with oil from deep formations (>5,500 feet) in the Williston Basin. This brine is some of the most saline water in the nation and can contain chloride concentrations that are near saturation. Brine disposal and handling methods use storage tanks and wells connected by a network of pipelines that include pits and injection into subsurface geologic units. These disposal and handling methods have resulted in contamination of surface water and shallow groundwater at multiple locations throughout the Williston Basin.

Using a combination of geophysical and geochemical methods, the U.S. Geological Survey (USGS) has delineated brine contamination in and near the East Poplar oil field along the western flank of the Williston Basin. Results of this effort show the brine is present throughout the shallow saturated zone in contaminated areas. The brine contamination has been documented for several decades and has not only affected the water quality of privately owned wells, but also the City of Poplar’s public-water supply wells.

The USGS, the Montana Bureau of Mines and Geology, and the U.S. Fish and Wildlife Service have identified brine contamination at multiple locations throughout the Medicine Lake National Wildlife Refuge, located in the northwestern portion of the Williston Basin. The source of the brine may be from buried storage pits that were installed in the mid- to late 1960s.

Concerns about current energy development of the Bakken Formation in the Williston Basin often focus on the hydraulic fracturing component and the associated chemical additives. Lessons from previous energy development in the Williston Basin indicate that concerns should also focus on the large volumes of brine that can inadvertently cause serious effects to water resources from oilfield infrastructure.

More information about these projects can be obtained at:

http://mt.water.usgs.gov/projects/east_poplar/index.html

http://steppe.cr.usgs.gov/

Energy and the Environment in the Williston Basin: Ongoing USGS Projects and Recent USGS Publications

Joanna Thamke
The Williston Basin has been a leading source for domestic oil and gas production since the 1950s and underlies about 135,000 square miles primarily in eastern Montana, North Dakota, and southern Saskatchewan. Today this region, which includes the oil-producing Bakken and Three Forks Formations, is in the midst of a modern energy boom, driven by technological advances in oil and gas development methods.

Multiple ongoing USGS projects are focused on various aspects related to energy and the environment in the Williston Basin. Specifically, these projects address brine contamination of shallow groundwater, wetlands, and streams; brine salt toxicity to invertebrates; groundwater availability; changes in groundwater geochemistry; changes in local land-use; surface water and groundwater chemistry; and trends in migratory bird populations. Principal investigators of these projects coordinate with multiple agencies and entities in addition to participating on bi-monthly conference calls within the USGS.

The USGS has also coordinated with multiple agencies and entities to prepare and release publications that discuss the relation between energy and the environment in the Williston Basin. These recent USGS publications focus on assessing brine-contamination vulnerability, delineating brine contamination plumes characterizing the spatial relations between energy and the environment, investigating the effects of brine salt on aquatic resources, and describing the hydrogeologic framework and conceptual flow model of the Williston Basin.

Information about these projects and publications can be located:

http://steppe.cr.usgs.gov/
http://wy-mt.water.usgs.gov/projects/WaPR/index.html
http://wy-mt.water.usgs.gov/projects/east_poplar/index.html
http://pubs.er.usgs.gov/

Physical and Chemical Characteristics of Tertiary and Upper Cretaceous Units in Laramie County, Southeastern Wyoming

Timothy Bartos
Most of Laramie County, located in southeastern Wyoming, is underlain by Tertiary and Upper Cretaceous lithostratigraphic units. Aquifers in the Tertiary lithostratigraphic units (Tertiary aquifers) compose the locally and regionally important High Plains aquifer system. These aquifers have been the primary source of groundwater for domestic, public supply, industrial, and irrigation use in the county, as well as for much of the High Plains area in southeastern Wyoming. Heavily utilization has caused local groundwater levels to decline. Concern about the groundwater-level declines has resulted in special regulation of new groundwater diversions from the aquifer system in these areas, as well as created substantial ongoing debate as to how to arrest the declines and where to obtain additional groundwater supplies within the county.

Consequently, the U.S. Geological Survey, in cooperation with the Wyoming State Engineer’s Office, is conducting studies to improve understanding of the geologic and hydrogeologic characteristics of Tertiary lithostratigraphic units composing the High Plains aquifer system. Additionally, stratigraphically lower and deeper Tertiary and Upper Cretaceous lithostratigraphic units underlying the High Plains aquifer system also are being studied to evaluate potential use as alternative sources of groundwater supply within the county.

The studies include detailed geologic and hydrogeologic characterization of the Tertiary and Upper Cretaceous lithostratigraphic units including lithologic description, lithostratigraphy, groundwater quality, hydraulic properties, groundwater age and recharge, hydraulic head/groundwater flow, and hydrostratigraphy. The detailed hydrogeologic characterization will provide water resources managers of the High Plains aquifer system with greater insight into the possibility of identifying and developing deeper and stratigraphically lower aquifers in Tertiary and Upper Cretaceous lithostratigraphic units.

Surface and Groundwater Data Collection and Application for Integrated Water Management in Nebraska

Colby Osborn
The Integrated Water Management Division of the Nebraska Department of Natural Resources (the Department) works to ensure a balance between water supplies and demands and to protect the rights of existing users of surface water and groundwater. Because groundwater and surface water are hydrologically connected, water supply management decisions should take into account the availability and use of both surface and sub-surface water supplies, as well as the interactions between them. This poster explores the path of hydrogeologic data for integrated water management in Nebraska from the collection of data through surface and groundwater monitoring, through model development and integration, to sharing data through the Department’s new INSIGHT website, and finally to the application of data during the integrated management planning process.

The Department first gathers information from a variety of monitoring networks. These data are then incorporated into the Department’s groundwater, surface water, and watershed models, which are then integrated to simulate the flow of water resources through the natural hydrologic cycle in combination with historical anthropogenic activities. Together, these models provide a better understanding of the complex interactions between groundwater systems and other hydrologic components. The Department’s INSIGHT website makes the results of these modeling efforts available to the public in an easy-to-use format. The data available on INSIGHT can be used by water managers, including those in Nebraska’s 23 Natural Resources Districts (NRDs), to support proactive water supply management decisions. Through the state’s integrated management planning and basin-wide planning processes, the Department and NRDs collaborate to work towards maintaining or achieving a balance between water supplies and demands. Effective water management decisions are based on the best available scientific data; therefore, the Department continually strives to identify areas where having additional data will help to present a more complete picture of a basin’s water supplies or demands.

Water Quality and Availability in the Upper Great Plains Aquifers

Jeremy Manley

Investigating the Temporal and Spatial Characteristics of Groundwater Discharge in the Loup River Basin

Christopher M. Hobza
Streams in the Loup River basin are sensitive to groundwater withdrawals because of the close hydrologic connection between groundwater and surface water. Groundwater discharge constitutes over 90 percent of streamflow in the Loup River basin in the Nebraska Sand Hills. The Upper and Lower Loup Natural Resources Districts, in cooperation with the U.S. Geological Survey, recently initiated a study to investigate the temporal and spatial characteristics of surface-water/groundwater interaction within the Loup River basin. Four stream reaches, totaling approximately 320 river miles, have been identified by the Upper and Lower Loup Natural Resources Districts as priority reaches where additional information is needed to protect stream flows. Currently, groundwater discharge is estimated from seepage runs completed in 2006, where streamflow was measured at various points along a stream’s reach, often up to 15 miles apart. Within the four stream reaches, a network of six coupled surface-water/groundwater gages will be installed, each consisting of a stream gage coupled with an observation well screened below the elevation of the streambed and instrumented with a groundwater-level recorder. Information from the network of monitoring stations will provide scientists and water managers with information about temporal and spatial changes in streamflow and groundwater discharge. Additionally, airborne thermal imagery will be collected over the four stream reaches to identify thermal anomalies in stream-surface temperatures, which may be indicative of focused groundwater discharge. Airborne thermal imagery will be verified with continuous water-temperature data from stream gages and self-logging thermistors. Mapped thermal anomalies will be further investigated using a variety of techniques, including water and streambed temperature surveys and potentiomanometer measurements.

Wyoming Groundwater-Quality Monitoring Network

Greg Boughton
The Wyoming Groundwater-Quality Monitoring Network is a cooperative program with the Wyoming Department of Environmental Quality, begun in 2009 to establish baseline groundwater conditions in the state. Representatives from the U.S. Geological Survey, Wyoming Department of Environmental Quality, U.S. Environmental Protection Agency, Wyoming Water Development Office, Wyoming Geological Survey, and Wyoming State Engineer’s Office formed a steering committee, which meets periodically to evaluate progress and consider modifications to strengthen program objectives.

Ambient or baseline monitoring is being conducted in “priority” areas where groundwater has been identified as an important source of drinking water to public and private water supplies, is susceptible to contamination, and is overlain by one or multiple land-use activities that could negatively impact groundwater resources.

Groundwater samples were collected from 146 existing shallow (less than or equal to 500 feet deep) wells from November 2009 through September 2012. These randomly selected wells were a mix of domestic, stock, municipal, and monitoring wells. Samples were analyzed for a broad suite of inorganic and organic constituents. Several different laboratories capable of varying reporting levels and using dissimilar data formats performed the analyses.

Values of physical characteristics, major ions, trace elements, nutrients, radionuclides, volatile organic compounds, and coliform bacteria were compared to federal and state regulatory water standards. Major-ion chemistry was characterized for different hydrogeologic units. Stable isotopes of hydrogen and oxygen were compared to the Global Meteoric Water Line and Local Meteoric Water Lines.

Water-quality data are stored in the USGS National Water-Information system data base. Data are publicly available and are used by interested stakeholders to establish baseline groundwater-quality conditions to serve as a reference to which future groundwater-quality data can be compared. Well owners were notified of results exceeding federal or state regulatory water standards.

Water Quality and Availability in the Upper Great Plains Aquifers (cont.)

Jeremy Manley

A Simplified and More Efficient Solution for Stream Depletion Analysis in MODFLOW

Gengxin Ou
Current processes being used at the Nebraska Department of Natural Resources for the calculation of stream depletions requires the performance of a change analysis, both a baseline run and a scenario run of MODFLOW, to calculate the baseflow difference. The current process for obtaining a stream depletion distribution pattern is computationally inefficient because separate model runs with a pumping well in each individual grid cell are required. This study proposes a simplified and more efficient solution to estimate a stream depletion rate at a given location by using coefficients of the baseline run in the scenario runs. Groundwater internal flow coefficients are head-dependent in the unconfined layer. However, the head change between two model runs is usually minimal compared with the aquifer thickness. In the stream package, streambed conductance can be changed as the wet radius changes with stream stage. Using the assumption that the accretion flow is negligible to streamflow, the change of the stream stage can be neglected. Since flow coefficients have been calculated in the baseline model run, the solution becomes very efficient and does not require the MODFLOW input files to be repeatedly read into the scenario run. The change in the head-dependent boundary flow and storage can then be calculated using the head difference. This solution dramatically reduces computer time (in both computation and IO) and noise because the new estimate is a change in heads. The change in heads can then be canceled out in the original model because the difference is small relative to the head. This presentation will describe the simplified and more efficient solution for stream depletion analysis.

Intentional Groundwater Recharge Through Canal Seepage in the Upper Platte River Basin of Nebraska

Jessie Winter
In the Upper Platte River Basin of Nebraska, due to the over-appropriation of hydrologically connected surface water and groundwater, state statutes require the Department of Natural Resources (NDNR) and the local Natural Resources Districts (NRDs) to offset streamflow depletions caused by surface water or groundwater uses initiated after 1997, and prevent depletions that would cause noncompliance with the Platte River Recovery Implementation Program interstate cooperative agreement. While some of these stream depletions can be made up through the retirement of surface water and groundwater irrigation, other offset schemes allow beneficial uses like irrigation to be maintained. Some such offset schemes involve the utilization of excess surface water flows, flows above what is already appropriated for surface water irrigation and other uses, through conjunctive water management. Conjunctive water management strategies take advantage of the connection between surface water and groundwater to increase the availability and reliability of the water supply as a whole within a region.

Conventional diversion of streamflow into unlined canals during the irrigation season typically results in seepage of water through the canal bottom during transit from the stream to the field. This water percolates into the unsaturated zone, making its way to the local aquifer. Excess streamflows during the non-irrigation season provide opportunities to divert flow into existing canals to recharge groundwater, increasing long-term water supply and availability within the basin. In 2011, flooding in the Upper Platte created an initial opportunity to test the viability of such a conjunctive water management project. Since then, the coordinated efforts of NDNR, NRDs, and irrigation districts have resulted in several diversions of excess flows into irrigation canals, recharge pits, and surface water reservoirs. Initial analytical evaluations show positive impacts to streamflows continuing well into the future. These recharge events can also be analyzed using numerical groundwater models.

Modeling Accretions to Baseflow in Response to a Scenario of High-Flow Diversions into Canals

Colby Osborn
Snowmelt in the early spring and heavy thunderstorms can create high streamflow events and pose flooding threats to areas along streams in the Central Platte River Basin in Nebraska. For floodwater relief and the retiming of water for later use, the State of Nebraska implemented a proactive management approach in partnership with local natural resources districts and irrigation districts, diverting the high flow into canals that extend into agricultural fields and allowing the diverted flows to recharge the aquifer. To make optimal integrated water management decisions, it is essential to estimate the amount and timing of changes to stream baseflow. Work already completed by the Nebraska Department of Natural Resources used analytical tools to evaluate the impacts of diverted flows. Numerical modeling is an additional tool available that complements analytical tools.

This numerical analysis uses COHYST, a regional groundwater model, to gain a better understanding of the relationship between the diversion of water into canals along the Platte River and the resulting impacts to streamflow. Thirteen canals within the Central Platte River Basin received an arbitrary diversion of 100,000 cubic feet per day for the first simulation month. After using data from the model runs, the accretion to baseflow from individual canals was calculated. After the 21 years modeled, the percentage of the diversions that returned to the stream ranged from approximately 30 percent to nearly all of the total diverted water, and the timing of the peak return ranged from shortly after the diversion to a couple of years afterwards. These variations were most consistently dependent on the canals’ proximity to the stream. Fluctuations and anomalous spikes found within the baseflow response curves were concluded to be a result of numeric noise. This presentation will describe the analysis and results.

Water Quality and Availability in the Upper Great Plains Aquifers (cont.)

Kevin Boyce

Groundwater Availability and Flow Processes in the Williston and Powder River Basins, Upper Great Plains

Joanna Thamke
The recent oil and gas development in the Williston Basin and the Powder River Basin in the Upper Great Plains provides an opportunity to examine the groundwater and energy nexus in this region. A substantial amount of water is needed for energy development in these basins, and the primary groundwater sources are glacial sand and gravel aquifers and the lower Tertiary and Upper Cretaceous bedrock aquifer systems.

The U.S. Geological Survey is preparing a groundwater availability study of these regional aquifer systems, which includes a numerical model of groundwater flow. The hydrogeologic framework and conceptual model have been published and include a three-dimensional framework, a lithostratigraphic correlation chart that spans the states and provinces, potentiometric surfaces, a description of groundwater flow processes, and quantification of recharge and discharge components. The published information is currently being used to develop inputs for the numerical model of groundwater flow for the Williston Basin, which include initial and boundary conditions, aquifer geometries, and calibration targets. A calibrated steady-state model will be used to estimate initial hydraulic properties and conditions for a transient simulation spanning 1960-2005. The transient simulation will be calibrated to hydraulic-head measurements and stream base flows for the same time period. The transient model will be used to simulate aquifer responses to increases in groundwater withdrawals and different climate scenarios.

This study will provide an assessment of how the groundwater resources have changed over time, an estimate of groundwater-flow directions and inter-aquifer connection, and an estimate of the possible effects of potential future environmental and anthropogenic stresses on groundwater in the Upper Great Plains.

Project web site: http://mt.water.usgs.gov/projects/WaPR/

Groundwater-Quality Sampling for the USGS National Water-Quality Assessment Program in Nebraska During 2015

Jonathan Traylor
During spring and summer 2015, the U.S. Geological Survey (USGS) Nebraska Water Science Center conducted extensive groundwater quality sampling as a part of the USGS National Water Quality Assessment (NAWQA) program. The main goal of NAWQA is to provide high quality, long-term datasets to aid in understanding natural and anthropogenic factors that affect water quality. Data from three separate NAWQA studies—Principal Aquifer, Vertical Flow Path, and Agriculture and Land Use—is being used to characterize the water quality of three different aquifers in Nebraska. All samples collected for these three studies were analyzed for organic, inorganic, and age-dating constituents. For the Principal Aquifer study, 32 public-supply wells, screened in the deeper portions of the High Plains aquifer, were sampled to evaluate the quality of public drinking water supply. For the Vertical Flow Path study, 15 moderate-depth domestic wells and 15 shallow-depth monitoring wells, screened in shallow quaternary aquifers within the High Plains aquifer in eastern Nebraska, were sampled to evaluate age-related trends of constituents across different land uses. For the Agriculture and Land Use study, 30 monitoring wells in the shallow glacial aquifers of eastern Nebraska were sampled to evaluate the amount of agricultural chemicals. All samples were collected and analyzed using the rigorous and comprehensive NAWQA protocols and methods ensuring high quality, consistent, and reliable data.

Integrated Water Management Modeling for Climate Variability Study in the Niobrara River Basin

Mahesh Pun, M.S.
The Niobrara River Basin Study is a collaborative effort by the Nebraska Department of Natural Resources and the U.S. Bureau of Reclamation under the federal WaterSMART (Sustain and Manage America’s Resources for Tomorrow) program. The objective of the WaterSMART program is to make use of the best available science in the assessment of current and projected future water supply and demand with the goal of securing future water supplies. The technical analysis of the Niobrara River Basin Study involves an Integrated Water Management Model which consists of three different water resources models—a groundwater model, watershed model, and surface water operations model. The three water resources models are integrated with each other to simulate the flow of water through the natural hydrological cycle as historical changes occurred through time due to anthropogenic activities. Projection results of future climate from the Intergovernmental Panel on Climate Change are incorporated into the Integrated Water Management Model to assess projected future water supply and demand. This talk will explore the mechanics of the Integrated Water Management Model as used to assess the impacts of climate variability in the Niobrara River Basin and will discuss some results of the technical analysis.

Water-Level Changes in the High Plains Aquifer, Predevelopment to 2013 and 2011-2013

Virginia L. McGuire
The High Plains aquifer underlies 111.8 million acres (175,000 square miles) in parts of eight states—Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming. Water-level declines began in parts of the High Plains aquifer soon after the beginning of substantial irrigation with groundwater (about 1950). The U.S. Geological Survey, in response to a request from Congress, has monitored water levels in the aquifer since 1987 using water-level data from local, state, and federal entities.

In 2005, estimated irrigated acreage in the aquifer area was 15.5 million acres, or about 14 percent of the aquifer area. In 2005, estimated groundwater withdrawals from the High Plains aquifer for irrigation were 19 million acre-feet, or about 95 percent of total groundwater withdrawals.

Water-level changes from predevelopment to 2013 were assessed using measurements from 3,349 wells. Water-level changes from predevelopment to 2013, by well, ranged from a rise of 85 feet to a decline of 256 feet. Area-weighted, average water-level change from predevelopment to 2013 by state ranged from a rise of 1.8 feet in South Dakota to a decline of 41.2 feet in Texas and was an overall decline of 15.4 feet.

Water-level changes from 2011 to 2013 were assessed using measurements from 7,460 wells. Water-level changes from 2011 to 2013, by well, ranged from a rise of 19 feet to a decline of 44 feet. Area-weighted, average water-level change from 2011 to 2013 by state ranged from 0 feet in South Dakota and Wyoming to a decline of 3.5 feet in Texas and was an overall decline of 2.1 feet.

Total water in storage in the aquifer was about 2.92 billion acre-feet in 2013. This was a decline of about 266.7 million acre-feet since predevelopment and a decline of 36.0 million acre-feet from 2011 to 2013.

Western Water Use Management Modeling— A Decision Support Tool for the Southern Nebraska Panhandle

Thad Kuntz, PG
The Western Water Use Management Modeling is a cooperative effort between the North Platte Natural Resources District (NRD), South Platte NRD, and Nebraska Department of Natural Resources to create a robust modeling tool for water resource management decisions. The NRDs are local government entities and are responsible for regulating and managing groundwater pumping. The model extends from the Wyoming-Nebraska border in the west to Ogallala, Nebraska in the east and from Alliance, Nebraska (in the middle of the Nebraska Panhandle) in the north to the Nebraska-Colorado border in the south. The primary surface water bodies within the model are the North Platte River, South Platte River, and Lodgepole Creek. The primary groundwater aquifers are the alluvial and High Plains aquifer systems. The modeling consists of a surface water operations model of the North Platte River system that provides a portion of the estimated pumping, canal operations and recharge, and river operations; a regionalized soil water balance model to estimate crop consumptive use, groundwater pumping, and recharge; and a groundwater model to provide storage amounts and movement of water through the alluvial and High Plains aquifers. The three models are partially integrated and share datasets, with each model providing outputs and feedback for use in calibration. Extensive climate, land use, hydrologic, hydrogeologic, and metered agricultural, municipal, and industrial pumping information was utilized to create models that simulate hydrologic and hydrogeological conditions from 1953 through 2013. These models are being utilized by the NRDs for day to day operations and regional to subregional management decisions. Recent studies have included aquifer life analyses of the High Plains Aquifer and well depletion quantification to rivers and streams.

Water Quality and Availability in the Upper Great Plains Aquifers (cont.)

Russ Dahlgren

Forest Service Stewardship of Groundwater Resources on National Forest System Lands

Elizabeth Berger
The National Forests and Grasslands were established in large part to improve the management of lands that provide freshwater to the nation. The U.S. Forest Service is responsible for managing 193 million acres of public lands that are the source of about 14 percent of the nation’s overall freshwater supply and approximately one-fifth of the municipal supply. Groundwater plays a significant role in sustaining those water supplies. In recent years, attention to groundwater has become more pronounced due in part to droughts, and the public and the courts have increasingly expressed expectations that the Forest Service will address potential impacts to groundwater resources as part of its decision making.

To help meet these expectations, the Forest Service has been working on national direction to its decentralized field units on how to fulfill the agency’s stewardship responsibilities for groundwater, recognizing state and tribal authorities for water allocation and water quality protection. The goal is to make Forest Service decision making more consistent, credible, predictable, and transparent and help the agency be a better partner with states, tribes, and others when decisions are being made about uses of National Forests and Grasslands that may affect groundwater.

In May 2014, the Forest Service published for public comment and initiated tribal consultation on a proposed directive (internal instructions to agency offices in 44 states and territories) on groundwater resource management, Forest Service Manual 2560. The Forest Service received over 250 comment submittals containing more than 2500 individual comments. In response to the concerns raised about the proposed directive, the Forest Service stopped the directives process in December 2014 and is proceeding with additional engagement with states and tribes. The agency wants to make sure it clearly understands their concerns and can appropriately address them before proceeding with public comment and tribal consultation on a new directive.

Tracking Montana’s Groundwater

John LaFave
In Montana, more than 200,000 wells withdraw about 285 million gallons of groundwater per day. Most wells (93%) provide domestic or stock water, but account for only 12 percent of groundwater withdrawals; irrigation, public water supply, and industrial wells—7 percent of all wells—account for 88 percent of withdrawals.

Since 1993, the Montana Ground Water Assessment Program has been monitoring groundwater levels in the state’s major aquifers. The monitoring network consists of more than 900 wells, from less than 10 to more than 3,600 feet deep, that provide data for unconfined alluvial, deep basin-fill, and deep confined bedrock aquifers. Some of these wells have been consistently monitored since the 1950s.

Groundwater levels vary seasonally and from year to year in response to changing climatic conditions, nearby groundwater withdrawals, and changing land use. Data from the long-term monitoring network have helped document the effects of: (1) climatic variability on the Madison Limestone aquifer near Great Falls, (2) groundwater development on the Fox Hills–Hell Creek aquifer in eastern Montana, (3) land use impacts on the alluvial aquifers in southwest Montana, and (4) the dynamic adjustment of water-level fluctuations in response to groundwater development in the deep aquifer of the Kalispell valley in northwest Montana.

These examples highlight the importance of long-term, systematic groundwater-level monitoring to: (1) develop a comprehensive understanding of how aquifers respond to different stresses, and (2) develop meaningful evaluations of the groundwater supply.

Welcome

Patrick Tyrrell

WyCEHG Discussion

Brad Carr, Ph.D.