NU Water-Related Research in Hall County

The hydrologic properties of channel sediments have an important role in controlling hydrologic process in streams. This study focused on the water exchange between a stream and an aquifer induced by groundwater withdrawal, with the purpose of investigating the interbedded feature of channel sediments and to evaluate its effects on the calculation of streamflow depletion. Field work was conducted at nine study sites between Kearney and Columbus during the summers of 2005 and 2006. Direct-push techniques were used to produce electrical conductivity logs and to collect sediment cores. Permeameter tests were conducted on the sediment cores. Stream-aquifer simulation models were used to evaluate streamflow depletion for various types of channel sediments.

Sediment core samples were categorized into four groups:

• sand and gravel,
• sand and gravel with interbedded silt and clay layers,
• fine sand with silt or clay layers, and
• silt and clay with some sand and gravel.

In general coarse sediments occur in the western part of the study area, and the amount of fine sand, silt and clay increases eastward along the river. However, the sediments in the top two meters are about the same for all the sites, consisting mainly of sand and gravel.

Project Support

The terms of the Cooperative Agreement for the Platte Basin and the Supreme Court settlement decision for the Republican Basin both require that Nebraska reduce its consumptive use of irrigation water. This analysis evaluated the economic and the budgetary costs of meeting these requirements. Both the on-farm and off-farm costs were evaluated for both land retirement and water allocation programs, implemented in several different ways, over three alternative time periods, 10, 25 and 50 years.

The on-farm economic costs were defined as the change in net farm income associated with less irrigation. Off-farm economic costs were defined as the statewide change in household income resulting from changes in irrigation, as the effects ripple through the Nebraska economy. Budgetary costs were defined as the cost to the state budget (taxpayers) of policies which compensate irrigators for reducing consumptive use are implemented. Statewide economic costs were found to be lower for land retirement than for allocation programs, assuming the same total change in consumptive use. Total budgetary costs depended primarily on: where the irrigation reductions occurred (proximity to river); on how long the program was continued (number of years), and on whether irrigation was reduced voluntarily with incentives, or by regulation, or by some combination of regulation and incentives. It was found that policy makers could minimize the cost of reducing consumptive use from irrigation and augmenting stream flow by purchasing rather than leasing irrigation rights, by using a regulatory rather than a willing seller incentive approach, and by reducing irrigation at locations close to the river.

The Sand Hills, the largest sand dune area in the Western Hemisphere, is now stabalized by native grasses. This was not always the case. The Sand Hills have mobilized several times over the last 10,550 years. Major droughts destabilized significant portions of the Sand Hills as recently as 1000 years ago. The stability of the Sand Hills affects not only hundreds of cattle ranches, but also the recharge of the High Plains Aquifer. Of the total groundwater stored in this vast aquifer, 65% occurs in Nebraska and over half of that lies under the Sand Hills. The groundwater connection is obvious throughout the region. Due to the high water table, interdunal valleys in portions of the Sand Hills contain extensive complexes of lakes, wetlands, and naturally sub-irrigated wet meadows, which together cover over 10% of the landscape.

The Sand Hills Biocomplexity Project is a major federal project led by Professor Wedin. The project is aimed at testing whether:

1. Evapotranspiration (ET) from wet valleys buffers the impacts of short-term drought on upland grasslands through local climate feedbacks. (resistance stability)
2. When wetlands go dry, the combined effect of lost upland grass cover and lost wetland ET creates a desertification feedback that amplifies drought impacts.
3. Since subregions of the Sand Hills differ in their extent of interdunal wetlands, subregions respond differently to paleo and historic droughts, thus enabling landowners to prepare for future droughts.
4. Increased groundwater recharge when dunes are bare hastens the rise of groundwater levels, which, together with the rapid recovery of warm season grasses, restabilizes the dunes. (resilience stability)

The project's Grassland Destabilization Experiment (GDEX) is studying what happens to a Sand Hills dune when the vegetation dies. Researchers have created 10 circular plots at the Barta Brothers Ranch, each 120 meters in diameter, and used herbicide to kill all the vegetation on several of them. The plots are kept clear of vegetation, so that information on vegetation coverage, root mass, soil organic matter, and sand movement may be monitored and recorded to determine the stability of the plots. Results indicate that the Sand Hills may be more stable than previously thought; that is, ersosion is just starting to occur were vegetation was killed two years ago. Additional studies are needed to determine what happens when sand dunes become mobile.

As a part of this project, Professor Vitaly Zlotnik carries out research on groundwater recharge, hydraulic properties of the dune cover, and the climate change effects on groundwater recharge.

Nebraska’s native prairies are a valued resource and under constant anthropogenic demand and degradation. By engaging land owners in voluntary programs, the Platte River Habitat Partnership aims to restore and enhance this important natural resource. In this project, the Public Policy Center conducted a survey to assess land owners’ perceptions of the Platte River Habitat Partnership to help direct the Partnership’s second phase. Specifically, land owners who live in the region covered by the Partnership but did not participate, and those that did participate in the Partnership were surveyed in order to answer four key questions: 1. How knowledgeable are these land owners about the Partnership? 2. What is the nature of these land owners’ interactions with the Partnership? 3. How is the Partnership itself generally perceived by these land owners? 4. What would encourage land owners who had not participated in the Partnership to participate?

The goal of this project is to enable onsite wastewater treatment system professionals to apply science-based onsite wastewater design, installation, and maintenance practices and thereby protect water resources and human health. As of December 31, 2005, onsite professionals must pass exams to be certified pumpers, installers, and/or inspectors in the state of Nebraska. In-depth curriculum for Nebraska onsite wastewater system installers, inspectors and pumpers was developed to address this issue. The curriculum helps individuals prepare for exams, as well as help professionals apply science-based practices to protect water resources.

During 2005 and 2006, UNL Extension had 733 educational training contacts. Knowledge and competency was demonstrated by 86 percent passing their exam(s). Results from a follow-up survey of 460 of those who had attended training indicated pumpers (90%), installers (99%) and inspectors (100%) increased knowledge. Pumpers (76%), installers (71%), and inspectors (90%) reported they had made practices changes which would result in water quality and human health being better protected.

Certification training continues on an annual basis and new curriculum is being developed for advanced alternative treatment systems. These systems can achieve greater water quality protection in vulnerable areas including those with high groundwater levels and/or sandy soils. Merrick, Hall, and Hamilton Counties have geographic areas of high risk from traditional onsite wastewater treatment systems due to these factors. Alternative systems could greatly reduce the risk of water quality degradation from nitrate and other contaminants in these areas.

Educational materials have also been developed and delivered for homeowners with onsite systems. The goal is to empower rural homeowners to protect water resources and human health through application of science-based onsite system maintenance and operation practices. Training was delivered in Grand Island and to 50 residents with onsite systems at Turtle Beach near Central City.

This paper evaluated spatial patterns of nitrate-nitrogen contamination of groundwater in the High Plains Aquifer in the area of Dawson, Buffalo and Hall counties in the South-Central Platte River Valley of Nebraska. Geostatistical approaches including ordinary kriging, indicator kriging and cokriging, were used to analyze 1514 samples drawn from 465 irrigation wells over a 30-year period. The spatial trends of the nitrate-N concentration suggested that about one third of the aquifer in the area had been contaminated by nitrate-N above a level of 5 ppm.

The small areas along with the South-Central Platte River Valley were classified as high risk with the nitrate-N level above 10 ppm. The probabilistic maps exceeding thresholds (10 and 5 ppm) for the nitrate-N concentrations of the groundwater were created to assess vulnerability. The areas with the nitrate-N levels exceeding 10 ppm at an extremely high risk (>75%) were delineated for the future nitrate priority areas of management. Temporal trends of the nitrate-N contamination at 465 sampling locations were analyzed for a period of 30 years. Thirty-seven (37) sampling wells, accounting for 8.0% of the total sampling wells, were identified with an increasing trend, in which the maximum increase was estimated at 4.20 ppm per five-year. Twenty-nine (29) wells were identified with a decreasing trend, in which the average decrease was 0.48 ppm per five-year. It was concluded that the groundwater nitrate-N contamination in some areas, such as the middle area of Buffalo County, was improving, but was worsening in other areas, such as the middle portion of Hall County and the south-eastern corner of Buffalo County. It was found that groundwater irrigation level (or well density) has a positive correlation with high concentration of nitrate-N.

When new Environmental Protection Agency Safe Drinking Water Act standards for arsenic and uranium were enacted, 82 Nebraska public water supplies had arsenic concentrations above the maximum level allowed and 20 had uranium above the standard, including public water supplies in Hamilton, Hall, and Merrick counties. Since arsenic and uranium are naturally occurring in rocks and soil, private water supplies in these geographic areas could also be at risk of having elevated concentrations, possibly putting families at risk from chronic exposure.

A UNL Extension team with a drinking water focus developed and delivered training to UNL Extension faculty/staff in targeted areas at high risk for naturally occurring arsenic and/or uranium. Twelve training sessions were delivered in 2005 including training in Merrick and Hall Counties. Thirty-nine extension personnel with a focus or job description other than drinking water were trained, including 3 in Hall County and 3 in Merrick County. Participants increased their knowledge of the topic in order to work better with owners of private drinking-water wells in the high risk areas. Of those returning an evaluation, 92% strongly agreed or agreed their knowledge increased in regard to arsenic and uranium occurrence, risk, testing, and treatment. These faculty and staff have gone on to provide information and education at the local level to private well owners.

Training on arsenic and uranium in drinking water was delivered at the Nebraska Well Drillers Winter Short Course in 2006 and information on arsenic in drinking water was presented in 2007. Nearly 300 water well professionals attended in 2006 and approximately 250 attended in 2007. Seven percent of 2006 participants evaluating the program indicated the arsenic and uranium program was the best topic during the event, and 19% indicated they were interested in learning more about the topic. Participants indicated they would use the information gained to "spread knowledge on arsenic and uranium to pivot system owners," "educate/inform constituents, customers," "expand markets in arsenic and uranium testing," or "provide safer water."

UNL Extension also delivered training on arsenic and uranium in drinking water at a Professionals Seminar in 2006. Thirty-eight professionals attended. Several professionals involved stated that the focused three-hour presentation gave them an excellent overview of the pertinent design issues which communities and engineers should consider when selecting a method of dealing with high arsenic and uranium levels. They especially appreciated the mix of technical presentations with a panel discussion by community members, regulators, and local engineers.

The Rainwater Basin is one of the most endangered wetland ecosystems in North America. This ecosystem is critical to many species including migratory waterfowl. Land use and runnoff from agriculture and cattle confinement operations are likely to be reducing the basin's health and diversity, however little information exists concerning macroinvertebrates. Twenty-two locations were assessed for water quality parameters, vegetation composition, and macroinvertebrates identified to genus. Samples were collected biweekly starting in April through July for three years. Macroinvertebrate diversity was impacted in areas with little buffer although the effects were not pronounced. Institution of a more effective vegetative buffers strip may reverse this trend to improve ecosystem quality and provide for invertebrate resources for migratory birds.

Click here to see a poster about this research

River otters (Lontra canadensis) are native to Nebraska but were extirpated by the early 1900s. River otters became reestablished in Nebraska following their reintroduction in the mid 1980s and early 1990s by the Nebraska Game and Parks Commission. The species is currently listed as threatened in Nebraska. Despite the high profile of the reintroduction and the otters' role as a flagship species, relatively little is known about river otter ecology in Nebraska. In order to provide information for management, research was conducted to determine home range, habitat use, overnight movement distance, and annual survival of river otters in the central Platte River of Nebraska.

Eighteen river otters were trapped, implanted with telemetry transmitters, and tracked during 2006-2009. Researchers obtained 996 telemetry locations and constructed 13 annual home ranges. Male home ranges were larger than female home ranges. Habitat use was determined by comparing used versus available habitats using compositional analysis. Open water was used more than any other habitat type in all three comparisons tested.

Nineteen overnight movements were recorded (465 total telemetry locations) for four river otters during 2007-2008. Movements during January-February, when NGPC conducts winter bridge surveys, were lower than during the rest of the year. Annual survival was 100% as no river otter mortalities were detected during the study period.

River otters in the central Platte River select open water over other habitat types, exhibit reduced movements during winter months, and have high annual survival. This information will be used by NGPC to assess the status of river otters in Nebraska and direct management efforts for the species.

Click here to read Brenda Pracheil's dissertation on Paddlefish populations

Catfish angling is popular throughout the United States and catfish are the most sought after fish species in the Platte River. However, catfish management in the Platte River is minimal as little is known about current populations. The objective of this study was to determine the current status of channel catfish and flathead catfish populations in the central and lower Platte River. Specifically, the study evaluated population characteristics including relative abundance, size structure, condition, age, growth and mortality.

Channel catfish are much more abundant than flathead catfish in the Platte River. The current Platte River channel catfish population appears to be average, comparable to many Nebraska and Midwestern rivers. Population characteristics displayed considerable variation along the Platte River and some longitudinal patterns were evident. Channel catfish in the central Platte River had lower relative abundances, higher condition, greater size structure, faster growth and lower mortality compared to lower Platte River channel catfish. Key factors likely influencing differences in channel catfish population characteristics are prey availability, flow modifications, habitat characteristics, tributary inflows and angler exploitation. Water manipulations from the Loup River Power Canal were also identified as a possible negative influence on lower Platte River channel catfish populations because hydropeaking is likely creating a stressful environment. However, channel catfish in the central Platte River appear to have benefited from recent high flows that likely increased productivity and food availability in the central Platte River.

Tony Barada's Master's Thesis on Catfish Population Dynamics in the Platte River

Lindsay Vivian's Master's Thesis on Platte River Caddisfly