NGWA Forum on Managing Groundwater and Surface Water as a Single Resource: Merging Science and Policies: Alphabetical Content Listing

Alan Matheson

Panel Discussion: How States Are Addressing Water Management Challenges

Fifty years ago, Colorado passed the Water Right Determination and Administration Act, starting down a path developing some of the most precise groundwater administration in the world. Groundwater regulations have largely been driven by the goal of preventing well pumping impacts on senior surface water rights. In the past, this has stifled acceptance of innovative ways to utilize aquifers. However, Colorado has evolved its groundwater administration and continues to do so in an effort to facilitate innovative aquifer management as a solution to address some of the State’s daunting water storage and drought contingency challenges.

This presentation will celebrate Colorado’s 50 years of historic water administration and will describe regulatory adaptation for the future. We will also discuss how technological advancements in groundwater science are allowing us to realize aquifer storage advantages within a strict regulatory environment.

Conjunctive Management of the Waters of the Humboldt River Basin, Nevada

Jon Benedict, Senior Hydrogeologist

The Nevada State Engineer has determined that evolving legal views of the treatment of the connectivity between surface water and groundwater, combined with the potential for conflict, necessitate conjunctive management in the Humboldt River Basin. In so doing, the State Engineer has chosen to promulgate regulations to mitigate conflict rather than to attempt to resolve the problem using curtailment by priority. The proposed regulations include the opportunity for groundwater users to file a mitigation plan, using replacement water to mitigate conflict from streamflow depletion. For those who do not file a mitigation plan, the regulations would require them to financially mitigate their injurious depletion. Mitigation funds would be collected by the State Engineer and then be used to compensate eligible surface water users. Determination of surface water conflict caused by groundwater pumping would be quantified in the field based on actual surface water deliveries. Determination of streamflow depletion caused by individual groundwater users would be quantified using groundwater models developed by the U.S. Geological Survey and the Desert Research Institute. Both assessment fees and compensation amounts would be based on the value of water established by an agricultural economist retained by the State Engineer.

Exempt Wells

Nathan Bracken

Impact of Vertical Discretization of Aquifers in Models on Simulation of Stream Aquifer Interaction

Mesut Cayar, Ph.D., P.E.

Stream-aquifer interaction will be one of the most difficult sustainability indicators to be evaluated by all the Groundwater Sustainability Agencies (GSAs) under California’s Sustainable Groundwater Management Act (SGMA) due to its complicated nature and lack of general understanding of the process and appropriate data. Integrated water resources models will serve as important tools for understanding and assessment of stream-aquifer interactions in many groundwater basins in California.

This paper investigates the minimum, optimum, and desirable number of aquifer layers needed to simulate stream-aquifer interactions with desired level of accuracy using two integrated water resources models, CA DWR’s IWFM and USGS’s MODFLOW models. Finer vertical layering will theoretically provide better estimates of stream-aquifer interaction if supported with appropriate filed data. However, in a real world, the calibration parameters might take away the gains made by finer discretization, specifically for big scale regional models. Many test cases were developed to evaluate the sensitivity of vertical discretization on model output related to stream-aquifer interaction due to pumping from a well based on the distance of the well from the stream, depth of pumping and range of various aquifer and stream bed parameters such as aquifer hydraulic conductivity, storage coefficient, and stream bed conductance.

Integrated Remote Sensing, Groundwater Monitoring & Modeling to Manage Groundwater-Dependent Ecosystems (GDEs)

Brian Schmid

California’s Sustainable Groundwater Management Act requires establishing measurable objectives, trigger thresholds and management actions to protect GDEs. Effective resource management must consider groundwater hydrology, surface-groundwater interaction, plant physiology, and habitat quality. We will discuss projects where remote sensing data were used to assess GDE stress and establish management action thresholds related to groundwater extraction, and present an approach that correlates GDE stress and habitat suitability indicators with hydrologic indicators to establish GDE management frameworks.

Satellite data were used to map spatial and temporal changes in Leaf Area Index (LAI) and wetland free water surface area, which are useful indicators of wetland health and productivity. For a site in eastern California, LAI over a 5-year period was compared to baseline conditions, and effects of groundwater extraction quantified. A change threshold was developed to trigger on-the-ground GDE surveys of habitat quality and degradation. The findings of these surveys and the remote sensing data were used to prepare a Habitat Suitability Index model and develop groundwater pumping prescriptions.

We propose a process which correlates remote sensing metrics of GDE stress with groundwater levels, stream baseflow, seepage discharge, ponding depth or other hydrologic indicators to establish a system of thresholds and escalating management actions.

Managing Groundwater and Surface Water--Putting Utah's Water Strategy to the Test

Jeff Davis

In 2017, Utah’s Governor Herbert received the recommendations of comprehensive water strategy on the future management of groundwater and surface water resources for the state. It is a difficult situation with Utah being one of the driest states in the country and experiencing a booming economy that is expected to double the population before 2060. One city, Provo is facing the challenge of protecting ownership of water rights, replenishing diminishing underground aquifers, and providing a sustainable water supply for its growing population. Currently, a number of aquifer storage alternatives are being investigated to meet these challenges and this presentation will address these alternatives and how success can be achieved.

Need for Essential Data/Collaboration for Practical Policy: Case Study of Collaborative Federalism and Management

Sara Larsen

The US Forest Service published the Proposed Directive for Groundwater Resource Management in the Federal Register in May, 2014, to set policy for groundwater management and use on USFS lands. It included direction for agency activities, approvals, and authorizations, protection for source waters, water conservation, and procedures for reviewing new applications for groundwater withdrawals on Forest Service lands-- and a provision for continuous measuring and reporting to USFS quarterly, of volumes of water extracted by community water systems (CWS) and high-capacity wells (> 35 gpm) on or near USFS lands. Some states, including members of the Western States Water Council (WSWC) and Western Governors' Association questioned USFS authority to require and agency capacity to review and monitor states' groundwater. During USFS/WSWC conversations, regarding the directive, the parties discussed the extent of the impact the new regulation would have on water users on or near USFS lands, the states, and USFS staff. Given the directive language, tens of thousands of well owners within and adjacent to USFS lands would be required to measure/report well use. Conversations between USFS/WSWC highlight the advantages gained by early and substantial engagement between federal and state agencies with water management responsibilities in the West.

New Ways of Looking at Water Resources Data vs. Instincts)

Todd Halihan, Ph.D., P.Gp.

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Resilience from Below: Proactively Managing Groundwater to Sustain Communities and Nature in an Uncertain Future

Maurice Hall, Ph.D.

2019 David Keith Todd Lecture

Groundwater provides a wide array of services to support our economy and communities. Perhaps most obviously, it captures distributed rainfall and delivers it to wells. It also sustains rivers and streams, supports groundwater-dependent ecosystems, and serves as an incredible storage reservoir. Yet, except for a few notable exceptions, our groundwater basins, these amazing natural infrastructure facilities, are largely managed passively, if they are managed at all. Even the most successful examples of proactive groundwater basin management tend to be focused primarily on one service – sustained supply to wells. Inevitably, this passive or singularly focused groundwater management means that other groundwater services are compromised over time. With a bit more attention and sophistication, however, the multiple benefits that groundwater basins provide can be preserved, and in some cases, enhanced.

In his David Keith Todd Distinguished lecture for 2019, Maurice Hall will share his vision on how more holistic and inclusive groundwater management can increase the resilience of our water supply and sustain and enhance the services that groundwater basins provide for a wide range of stakeholders.

Riverbank Filtration Provides Natural Filtration of Surface Water

Henry Hunt, CPGS

Riverbank filtration is a natural process that permits surface water to be infiltrated into alluvial aquifers to replenish groundwater pumped from a well, gallery, or other water-producing structure. As water is pumped from the well, the water table is lowered resulting in a reversal of the hydraulic gradient that would normally discharge groundwater to the surface water source. Once groundwater has been pumped sufficiently, the surface water that is replacing groundwater from within the aquifer receives very slow filtration by riverbank and riverbed sediments as it migrates toward the well screens and pumps. During this slow infiltration, suspended particulates, such as turbidity and organic matter, are naturally filtered by the soils typically providing a consistent water quality, often characterized as of groundwater quality (or not under the direct influence of surface water) and thus not requiring full surface water treatment. Hydrogeological testing can illustrate the recharging of the pumped water by surface water to meet surface water rights, where applicable. Case examples of operating systems, the system characteristics and water quality issues for several utilities will be presented.

Using Groundwater Models to Inform Water Management Decisions – from Months to Minutes!

James Schneider, PhD

Groundwater models are an indispensable source of information for the management of groundwater and surface water as a single resource. Their use is the only way to estimate and understand the effect of discrete changes to the groundwater system on surface water, and vice versa. By running a groundwater model both with and without a specific stress (e.g., a well or a recharge event) to the system, we can estimate how changes to that stress ripple through the overall hydrologic system.

These change simulations are straightforward in theory, however in practice they can become impractical given their esoteric nature. Unfortunately, one cannot simply pose the question and receive the desired information directly back from a model. There typically are numerous complicated steps that must be precisely completed by trained experts.

Leveraging technology to simplify this process enables water managers and policy makers to directly utilize complex models. Specifically, cloud technology has substantially reduced the time/cost of getting meaningful answers to these questions. Model evaluations that typically took months to complete, can now be efficiently executed in minutes using a standard laptop with an internet connection, and a little bit of curiosity.

Session II

Differentiating Plume Expansion from Regional Climate Effects for Ground Water Discharge Permits

Dan Bryant, Ph.D., PG

At facilities with known discharges of contaminants to ground water, a common regulatory requirement is to construct a sentry well network outside the contaminant plume and monitor those wells for plume expansion. Plume expansion is commonly defined by an increase in a contaminant concentration above a threshold based upon background concentrations and/or a risk assessment. Metals and common ions may exist both naturally and as contaminants, thus it is important to differentiate plume expansion from concentration shifts associated with natural phenomena. We present two examples from a site in northern Utah. Ammonia exhibited increases above protection levels in sentry wells, which could be interpreted as indicating plume expansion. Analysis of ammonia concentration and nitrogen isotopic composition in surface water, soil, and shallow ground water demonstrated that the increased concentration reflected regional climate effects rather than plume expansion. A similar analysis for barium in another area of the site yielded a similar result. Demonstration that the increases reflected climate-related hydrologic shifts rather than plume expansion averted compliance issues and additional monitoring requirements dictated by a ground water discharge permit. This example illustrates the need to consider regional climate patterns for similar permitting requirements.

Observing, Documenting, And Quantifying Flow From A Reservoir To A Karst Aquifer

Joe Yelderman Jr., PhD, PG

Surface-water/groundwater interactions from constructed reservoirs are less studied than the interconnections from natural lakes. Reservoirs have been constructed to manage water supply for a thirsty populace and provide flood protection for development. Stillhouse Hollow Reservoir was impounded in 1968 and anecdotal evidence of increased spring flow below the dam has been a topic of conversations ever since. A recent study combining flow, ionic chemistry, stable isotopes, and environmental DNA confirm surface-water connections from the reservoir to the local groundwater flow system. The surface-water/groundwater interaction between the reservoir and the aquifer exhibited heterogeneity characteristic of the karst aquifer but followed a general flow path. Results may have important implications regarding groundwater quality and use below the reservoir while quantity estimates may encourage management for enhanced aquifer recharge.

Physical Considerations in Managing and Modeling Stream-Aquifer Systems

Dan Stephens, Ph.D.

Aquifers overlain by streams are common throughout the US. The degree to which the streams connect hydraulically with the aquifer is critical to managing the coupled resource. Hydraulic connection controls the rate of exchange of water between the aquifer and stream, and vice versa. Hydraulic connection at a location may vary due to water table depth related to geology or to drawdown in the aquifer, it may vary with distance along the stream channel, and it may vary temporally with stream discharge rate and sediment load. Hydraulic disconnection may occur when there is an unsaturated zone beneath the channel or when a clogging layer develops. This presentation will briefly review the evolution of conceptual models of stream-aquifer hydraulic connections and the implications for resource management. Examples will e provided of data collected along selected western perennial and ephemeral streams.