Omaha sits on the west bank of the Missouri River, the longest river in North America. The Missouri drains 500,000 square miles — over one-sixth of the continental United States — collecting runoff from the Rocky Mountains, the Great Plains, and the most intensively farmed landscape in the world. By the time it reaches Omaha, the river carries the chemical signature of everything upstream.
The Missouri River and Alluvial Wellfields
The Metropolitan Utilities District (MUD) serves approximately 225,000 accounts in the Omaha metro, drawing water from the Missouri River and from alluvial wellfields adjacent to the Platte River (which converges with the Missouri just south of Omaha).
The alluvial wellfields are the backbone of Omaha’s supply. These wells tap shallow sand and gravel deposits along the river corridors, drawing groundwater that is naturally recharged by — and filtered through — river water. This riverbank filtration provides a first line of treatment, with the sand and gravel removing particles, bacteria, and some dissolved contaminants before the water reaches the well.
The Florence Water Treatment Plant processes Missouri River water directly, while the Platte South and Platte West wellfields provide naturally filtered groundwater. MUD’s treatment process includes coagulation, sedimentation, granular activated carbon filtration, and chloramine disinfection.
Atrazine: The Spring Surge
Atrazine is the herbicide that defines the Missouri River basin’s water quality challenge. Applied across millions of acres of corn and sorghum fields from Kansas to the Dakotas, atrazine washes into streams and rivers with spring rainfall — arriving at Omaha’s intake in a predictable annual pulse.
The EPA’s MCL for atrazine is 3 micrograms per liter, measured as a running annual average. MUD manages atrazine through activated carbon treatment and seasonal blending — using more alluvial wellfield water (which has lower atrazine due to natural filtration) during the spring peak, and drawing more river water when atrazine levels drop in fall and winter.
This strategy works, and Omaha’s finished water consistently meets the atrazine standard. But it requires constant monitoring and operational adjustments, and the costs — activated carbon isn’t cheap — are borne by ratepayers rather than the agricultural operations creating the contamination.
Beyond atrazine, the Missouri carries a cocktail of agricultural chemicals: metolachlor, acetochlor, and other herbicides have been detected in the river by USGS monitoring programs. The question of cumulative exposure to multiple low-level pesticides — each individually below regulatory limits — is an area of ongoing research.
The 2019 Flood: When the River Fought Back
In March 2019, a “bomb cyclone” hit the Great Plains, and the resulting snowmelt and rainfall caused catastrophic flooding across the Missouri River basin. In Omaha, the Missouri crested at historic levels, and levee breaches along the Platte River threatened the wellfields that supply a significant portion of the city’s drinking water.
MUD’s Platte West wellfield was inundated, temporarily cutting off a major source of supply. The utility scrambled to increase treatment at the Florence plant and bring backup wells online. The flood demonstrated the vulnerability of alluvial wellfields to the very river system they depend on — when the river floods, the wells flood too.
The 2019 flood also contaminated the floodplain with sewage, agricultural chemicals, and petroleum from storage tanks overwhelmed by floodwaters. As the water receded, this contamination percolated into the shallow aquifer, affecting water quality in the wellfields for months afterward.
MUD has since invested in flood hardening for its wellfield infrastructure and developed contingency plans for extended loss of wellfield capacity. But the Missouri River’s flood potential — potentially amplified by climate change — remains an existential risk for a water system designed around riverside wells.
Nitrate in the Shallow Aquifer
Nebraska has one of the most extensive agricultural groundwater contamination problems in the country. The state’s reliance on irrigated agriculture — powered by the Ogallala Aquifer and alluvial systems — has driven nitrate concentrations above the EPA MCL in many rural wells.
In the Omaha metro, MUD’s deep alluvial wells generally draw water below the nitrate-contaminated shallow zone. But private wells in Douglas and Sarpy counties — particularly in agricultural areas outside the municipal service boundary — are vulnerable. The Nebraska Department of Health and Human Services recommends annual nitrate testing for all private wells in the state.
What Omaha Residents Can Do
MUD’s treatment system is sophisticated and handles the Missouri’s challenging source water effectively. Key awareness points:
- Review the annual CCR — MUD publishes water quality data including atrazine and other agricultural chemicals.
- Test for lead if your home was built before 1986 — Omaha’s older neighborhoods have lead plumbing.
- Private well owners: test for nitrate, atrazine, and bacteria annually.
- Flood preparedness: keep bottled water on hand during spring flood season; the 2019 event showed how quickly supply can be disrupted.
If you’re concerned about your water quality, a certified water treatment professional can help you test your water and recommend the right solution for your home.