University of Nebraska-Lincoln, Conservation and Survey Division

Link to: University of Nebraska-Lincoln, Conservation and Survey Division Groundwater Information

NGWMN Contact:

Aaron Young

(402) 472-8339

The University of Nebraska-Lincoln, Conservation and Survey Division's (UNLCSD) is a water-level data provider to the National Groundwater Monitoring Network (NGWMN). UNLCSD's mission is to investigate and record information about Nebraska's geologic history, its rock and mineral resources, the quantity and quality of its water resources, land cover and other aspects of its geography, as well as the nature, distribution and uses of its soils. UNLCSD maintains a network of 59 real-time monitoring sites and provides data from 47 wells to the NGWMN Portal. UNLCSD has been a part of the Network since 2016.

UNLCSD provides water-level data from the High Plains Aquifer and other minor aquifers.

NGWMN Projects:

2016 Round 2: 8/15/2016 to 8/14/2017

Initial project to become a NGWMN data provider. Fifty-nine wells with continuous water-level data were added to the Network.

2017: 7/1/2017 to 3/1/2020

Project to provide well maintenance and replacement well drilling for the NGWMN. Well maintenance work is to replace fences at 17 wells located in cattle fields to protect the equipment. Well drilling work is proposed to replace 8 aging wells with depths range from 45 to 318 feet.

2018: 7/1/2018 to 6/30/2019

Project provides persistent data services and well maintenance activities. Well maintenance work is to pump eight wells to determine connection to the aquifer.

2019 Round 1: 7/15/2019 to 7/14/2020

One-year project to add High Plains water-level sites to the NGWMN. The new sites are to support the USGS High Plains aquifer assessment.

2020: 7/15/2020 to 7/14/2022

Project is to provide persistent data services for two years to ensure that data continues to flow to the NGWMN Data Portal, and that sites and site information are up to date They will also drill a new well to fill a gap in the High Plains aquifer.

2021 Round 1: 7/15/2021 to 7/14/2022

Project is to provide persistent data services for one year to ensure that data continues to flow to the NGWMN Data Portal and that sites and site information are up to date. They will also do borehole logging at 15 wells to ascertain the condition of the wells and to fill data gaps.

2021 Round 2: 11/1/2021 to 10/31/2022

Project is to replace continuous water-level monitoring equipment at 8 sites.

NGWMN Presentations:

December 2016 presentation to SOGW

Site Selection and Classification

Site Selection

Data history. Sites were selected with a reasonably continuous data set of at minimum five years.
Wells were located in the High Plains Aquifer, or in an aquifer or location hydrologic importance to Nebraska.
Sites where water level information is of regional or local importance.

Site Classification

Most wells in the UNL-CSD Network are in the NGWMN "Background" subnetwork. All wells included in the NGWMN are measured hourly, with daily readings at 12:00 UTC reported to the NGWMN. Wells were evaluated on a well-by-well basis.

Thirty-four wells with the following criteria were included in the "Background" subnetwork:

Minimum of 5 years data.
Hydrographs were evaluated for signs of human influence, and included if no sign of human influence was detected.
Proximity to nearby pumping wells. Minimum distance to nearby pumping wells varies by well location and local aquifer conditions, but must not be close enough to impact water levels in observation well.

Ten wells were categorized in the NGWMN "Suspected Changes" subnetwork. Although these wells may have suspected changes, they are still of great value in evaluating water-level changes. These wells were classified using the following criteria:

Minimum of 5 years data.
Hydrographs were evaluated and signs of possible human influence were observed. Signs of influence include:
High frequency (hours to days), low magnitude (0.5 foot or less) water-level changes. These changes are likely the result of pumping nearby domestic or stock wells.
Evidence of potential leakage between grouting at nested well sites.
Wells formerly used as irrigation wells, if evidence of prolonged recovery is suspected.

Five wells were categorized in the NGWMN "Documented Changes" subnetwork. These wells were classified using the following criteria:

In heavily pumped areas to show long-term trends in regional drawdowns.
In aquifers which are heavily pumped for irrigation.
Have a minimum of five years of data.

Although all wells are monitored at the same frequency (hourly, with daily values reported to NGWMN) UNL-CSD has wells classified as both trend and surveillance. Wells with robust data histories, which represent regional changes in an aquifer were placed in the trend category. Wells classified as surveillance are wells that can be compared against trend wells to get an overall picture of groundwater-level changes. Surveillance wells may be screened in secondary aquifers, or locations with different pumping histories than nearby trend wells.

Data Collection Techniques

Field techniques for water-level measurement:

Automated water level readings at all sites are recorded using pressure transducers manufactured by PMC Engineering. All pressure transducers have a 15 PSI range, except at sites #57 (Alliance), #59 (Burress2), and #58 (Rising City2), which have 30 PSI sensors. All pressure transducers have a reported accuracy of +/-0.1% of the stated pressure range.
Wells monitored for groundwater levels as part of the NGWMN are checked for sensor drift annually, using a Solinst model 101-P7 water level meter, Ser# 203199. All wells have been measured with the same tape since 2012. All water levels are recorded from the land surface, any stick-up of the well casing is subtracted from the water-level reading before broadcast.
No water quality samples are collected by the CSD as part of the NGWMN.

Data Management

Description of data quality and quality assurance processes:

Individual wells are checked for sensor drift annually. If sensor drift measured is in excess of 0.10 foot, readings are corrected assuming a linear sensor drift since last measurement. Data recorded in the database is checked monthly for obvious anomalous readings resulting from issues with electronics, weather, or maintenance/pumping at the well site. Any anomalous readings are deleted or field checked for accuracy.
A flow chart shows the process of data moving from the wells to the UNL-CSD and then to the NGWMN Data Portal.

Minimum data elements included in the Well Registry include the following fields: Unique Site Number, Site Name, State, County, National Aquifer, Local Aquifer(Where applicable), Site Type, Aquifer Confinement, Latitude, Longitude, Datum Altitude, Altitude Units, Vertical Datum, Water Level Network, Well Depth, and Well Depth Units.

The web service were developed using Microsoft .NET framework. The web services attach to a UNL database which stores water-level information collected by the UNL-CSD. The service allows for retrieval of data on all, or specific wells for a date range. Well construction and lithology data can also be accessed at separate web service links for each well, but do not have date range modifiers, as none are needed. Access of the service will allow USGS, or anyone who has the link, to retrieve water levels over specified time spans for requested wells which can, in turn, be posted to the USGS repository.

Other Agency Information

Additional information on ground water conditions in Nebraska is available at: https://snr.unl.edu/csd/water/