USGS Nebraska Water Science Center Science Highlights

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Scientists from the USGS Nebraska Water Science Center currently are working on the projects listed below. A summary of the project is available by clicking the project title. In addition to the projects listed below, we monitor streamflow, groundwater and water-quality throughout the state. Our data and site information is available on NWISweb.

Abbreviation: NRD, Natural Resources District

Green Infrastructure Monitoring in Omaha

Stormwater management methodologies are shifting from the traditional detention basin to a more green-infrastructure approach that stresses the importance of capturing, retaining, and treating stormwater. The implementation of green infrastructure uses various Best Management Practices (BMPs) to mitigate the detrimental effects of stormwater on water quality. A bioretention cell is a BMP that captures and treats stormwater by evapotranspiration and infiltration, thereby reducing the quantity of stormwater. Bioretention cells have been used for a number of years in the United States, and factors such as soil type, vegetation, evaporation rate, and cell design can affect performance. Site-specific scientific data is needed to evaluate and validate green-infrastructure BMPs. We will be monitoring the water balance of a bioretention cell in Omaha by measuring inflow, outflow, infiltration, and evapotranspiration (ET).

Project Website

For more information:
Kellan Strauch
402.328.4181
kstrauch@usgs.gov

Groundwater/Surface-Water Interaction Near the Confluence of the Elkhorn and Lower Platte Rivers

To sustain flows in the lower Platte River that are needed for municipal water supplies, water managers have proposed projects aimed at temporary storage of surface water in upstream parts of the basin to augment streamflows in the lower Platte River during low-flow periods. One area of interest to the Lower Platte North NRD and the Papio-Missouri River NRD is a reach of the lower Platte River that extends from downstream of Fremont to its confluence with the Elkhorn River.

Understanding how groundwater moves in the shallow alluvial aquifer along the lower Platte and Elkhorn Rivers is essential for conjunctive water management projects aimed at increasing base flows of the lower Platte River for municipal needs. We are using several approaches to improve the understanding of groundwater/surface-water interaction along the lower Platte and lower Elkhorn Rivers. The datasets produced with this project will provide cooperators with information needed to construct a numerical groundwater flow model, which can be used to estimate the volume of water that is exchanged between the Platte and Elkhorn Rivers under varying flow conditions. Specifically, we will

Instrument three groundwater-level recorder wells along a transect above the confluence of the Elkhorn and Platte Rivers. A coupled groundwater/surface-water gaging station will be installed at the Platte River near the Leshara gaging station to mirror the instrumentation set-up at the Elkhorn River at Waterloo coupled groundwater/surface-water gaging station.
Analyze and interpret data from a transect of groundwater level recorders and coupled groundwater/surface-water gages.
Plan and execute two synoptic groundwater level surveys during flow conditions that are of interest to the project cooperators.
Use the collected groundwater-levels and surveyed surface-water elevations to interpolate a groundwater-level surface, construct contours, and interpret flow paths
Use heat as a tracer to estimate hydraulic conductivity of the streambed sediment and estimate fluxes across the streambed.

For more information:
Chris Hobza
402.328.4133
cmhobza@usgs.gov

Missouri River Recovery—Chute Construction Monitoring

We are providing monitoring assistance related to the construction of off-channel aquatic habitat (such as chutes) along the Missouri River. This construction is currently done using a hydraulic dredge to excavate floodplain material. The dredge slurry is discharged into the main channel of the Missouri River. The potential impacts on nutrient and sediment levels in the river from this practice have created some concern from bordering states charged with reducing nutrient loading to the Gulf of Mexico. Our primary objective is to assess the downstream impact of hydraulic dredging discharge to the Missouri River.

We have collected data on 8 different sample events during active dredge operation periods at 4 sites along the Missouri River. Sampling occurred from fall 2013 through the 2014 navigation season.

Results from this study are being synthesized and will be released as a journal article.

For more information:
Dave Rus
402.328.4127
dlrus@usgs.gov

Missouri River Water-Quality Monitoring in Relation to Combine Sewer Overflow Systems near Omaha

In 2012, we began monitoring the Missouri River near Omaha to document water-quality changes in the river as the City improved their combined sewer overflow (CSO) system. The monitoring program, with both monthly (discrete) and continuous data collection, had to be designed to address a number of challenges:

Flows from CSO’s are a very small portion of the Missouri River receiving waters being sampled,
Trend detection is difficult because the hydrograph of the Missouri River within a year and between years is so variable
Contaminates can come from many upstream point and non-point sources which makes detecting what contaminates are coming from the Omaha area and which are coming from upstream sources hard, and
Simple grab samples do not represent the actual water quality of the river because the Missouri River is not well mixed.

To address these challenges, the monitoring program consists of four sampling sites on the Missouri River near Omaha. Monitoring at each site includes monthly discrete depth-integrated equal discharge water-quality sampling for

nutrients,
chlorine,
biological oxygen demand, and
total suspended solids.

Grab samples are collected to test for Escherichia coli. Each discrete water-quality sample collected is classified as local wet or dry and Missouri River high or normal flow. We also have three continuous water-quality monitoring sites at NP Dodge, Lake Manawa, and La Platte.

For more information:
Brenda Densmore
402.328.4145
bdensmore@usgs.gov

Papio-Missouri River NRD Groundwater-Quality Monitoring

The USGS, in cooperation with the NRD, has been collecting groundwater quality samples within the district, to support the district’s groundwater management plan, since 1992. We are currently monitoring the groundwater supplies for agricultural-related chemicals, and continuing to monitor contaminants that have been detected previously in the aquifers at at least 30% of the maximum contaminant level. These contaminants are naturally occurring, but have limits set for domestic drinking water supplies by Nebraska Title 118, which are similar to EPA drinking water standards.

We sample wells across the district on a 4 year schedule. We monitor domestics, industrials, municipal, stock and irrigation wells, which we refer to as the network wells. The NRD also has a set of dedicated monitoring wells installed in clusters across the district. These clustered wells are multiple wells in the same location, but are screened at differing depths within the aquifer.

In 2015, we sampled at 26 sites, for a total of 33 wells. We collected additional samples for quality control purposes that are not included in this total. We collected samples at 22 Platte/Elkhorn alluvial aquifer sites, and also collected samples at one area of interest clusters. The Tekamah cluster is sampled yearly as they have shown high nitrates parts of the aquifer. Additionally we collected samples at 3 Dakota aquifer sites. These sites had been previously sampled in 2013, and were sampled again to determine if concentrations of specific analytes had changed within the past two years.

Project Website

For more information:
Amanda Flynn
402.328.4144
aflynn@usgs.gov

Stormwater Bioretention Implementation, Monitoring, and Outreach, Douglas County

During rainfall events a portion of Omaha’s stormwater is collected into a combined sewer overflow (CSO) system. In a combined sewer system both sanitary and stormwater are collected into the same pipe network. Rainfall greater than approximately 0.1 inches creates a combined sewer overflow (CSO) and releases raw sewage into streams. One method of addressing the problem is by using detention and capture of stormwater with bioretention cells. We are monitoring the volume and quality of stormwater runoff entering the bioretention cells located in the Douglas County Health Center and the Eastern Nebraska Office on Aging to determine

effectiveness of bioretention cells at reducing flow into the combined sewer system,
effectiveness of current designs being applied in Omaha and surrounding areas, and
long term performance of bioretention gardens.

The water-balance components of the cells that are being measured/estimated are

flow into the cell,
precipitation,
evapotranspiration,
infiltration, and
flow out of the cell.

A 9-inch Parshall flume is used to measure inflow. A weather station at each site measures precipitation and meteorological data that will be used to calculate potential evapotranspiration. Infiltration is estimated using soil-matrix potential and water-content relationships. Outflow is estimated by measuring the depth of the water above the outlet pipe, and using orifice flow equations to estimate the amount of water leaving the cell.

Project Website

For more information:
Kellan Strauch
402.328.4181
kstrauch@usgs.gov

	Project Title	Cooperating Agency
	Green Infrastructure Monitoring in Omaha	EPA office of Research and Development (ORD), City of Omaha
	Lower Elkhorn Groundwater/Surface-Water Interaction	Papio-Missouri River Natural Resources District
	Missouri River Recovery Program Monitoring	U.S. Army Corps of Engineers
	Missouri River Water-Quality Monitoring near Omaha	City of Omaha
	Papio-Missouri River NRD Groundwater-Quality Monitoring	Papio-Missouri River Natural Resources District
	Stormwater Bioretention Implementation, Monitoring, and Outreach, Douglas County	Douglas County

USGS Nebraska Water Science Center

Congressional District 2

Congressman Brad Ashford

Research Projects