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.
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