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Nitrate in Drinking Water, 2003-2017: Nebraska

Between 2003 and 2017, tests detected elevated levels of nitrate (3 milligrams per liter, or mg/L) in the tap water supplies of 349 towns and cities in Nebraska, serving approximately 1.4 million people.

Contamination is getting worse in 159 of those community water systems1 – 46 percent, serving approximately 252,000 people. Nebraska towns and cities rely almost entirely on groundwater for drinking water: 99 percent of the systems that had increasing nitrate use groundwater, and serve 96 percent of all people in communities where contamination is getting worse.

Nebraska Communities With Increases in Nitrate Contamination, 2003 to 2017
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Source: EWG, from Nebraska Department of Health and Human Services data.

Average nitrate contamination across these communities jumped by 28 percent between 2003 and 2017. In 2003, average contamination was 4.42 mg/L. By 2009, average contamination had increased to 5.54 mg/L and continued climbing to 5.81 mg/L in 2017.

Average Nitrate Levels in Nebraska Communities Where Contamination Rose, 2003 to 2017

Source: EWG, from Nebraska Department of Health and Human Services data.

Health Hazards of Nitrate

Nitrate is a primary chemical component of fertilizer and manure that can run off farm fields and seep into drinking water supplies. Under the federal Safe Drinking Water Act, the legal limit for nitrate, measured as nitrogen, in drinking water is 10 mg/L. This limit was set in 1962 to guard against so-called blue baby syndrome, a potentially fatal condition that starves infants of oxygen if they ingest too much nitrate.

But more recent studies show strong evidence of an increased risk of colorectal cancer, thyroid disease and neural tube birth defects at levels at 5 mg/L or even lower. During the period studied, drinking water was getting worse in 126 Nebraska communities, serving approximately 226,000 people, that already had tested at or above 5 mg/L at least once.

Drinking water for approximately 64,027 of those people in 43 communities had already tested at or above the legal limit at least once and had increasing nitrate levels during the period analyzed. Of the 139 communities where nitrate exceeded the Environmental Protection Agency’s legal limit at least once, 19 systems, serving approximately 48,000 people, tested at or above the legal limit in 2017.

People who want to know the level of nitrate in their community’s water system can visit the Nebraska page of EWG’s Tap Water Database.

Who Is Affected?

Contamination was more likely to get worse in smaller communities between 2003 and 2017. Ninety-three percent of systems with worsening nitrate contamination served 3,300 people or fewer. For our analysis, systems were put into the EPA-designated size categories based on how many water customers they serve.

Number and Percent of Systems With Increasing Nitrate Levels, by System Size, 2003 to 2017

System size System count Percent of systems
Very small (<501) 94 59%
Small (501-3,300) 54 34%
Medium (3,301-10,000) 7 4%
Large (10,001-100,000) 4 3%
Very large (>100,000) 0 0%

Source: EWG, from Nebraska Department of Health and Human Services data.

Nitrate contamination was also more likely to get worse for people living in rural areas. Out of the 10 states in this analysis, Nebraska had the highest proportion of increasing nitrate systems that were rural – 86 percent – with just 14 percent that were urban, as defined by the U.S Census Bureau.


1 Community water systems are public water supplies that serve residents in cities and towns year-round.

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