Cities often send nitrates downstream after treatment

Des Moines, site of the world's largest nitrate-removal facility, last year dumped an estimated 13,500 pounds of the chemical back into the river, sending it downstream where other cities and towns had to once again remove it, a Des Moines Register investigation shows.

The federal government mandates that nitrates — the chemical linked to some cancers and the so-called "blue-baby syndrome" in which infants suffocate — be below certain levels in drinking water. But federal and state officials don't say what has to be done with nitrates after they're removed.

Recycling nitrates into fertilizers generally isn't an option since the typical removal system uses technology known as ion exchange. The nitrate-rich residue that remains from that process contains a salt solution, which is detrimental to vegetation.

And creating systems that remove the chemical naturally through processes that in some ways mimic swamplands can be prohibitive because they gobble many acres of land and cost millions of dollars. So many municipalities simply put the nitrates back into Iowa's waterways.

Water superintendents acknowledge the process of removing nitrates and then dumping them back into the water seems counterproductive — but note that it's legal.

"Symbolically, it's a troublesome issue for me," Des Moines Water Works Director Bill Stowe said in November when first questioned by the Register about nitrate-dumping practices. "Frankly, we're saying to the single farmer, 'Please don't do this,' and yet we're imitating the behavior we're trying to avoid."

Des Moines isn't alone in the practice.

Operators of the majority of Iowa's other 15 nitrate removal systems told the Register they also dump their nitrates back into water or local sewer systems after initially removing them from their town's drinking water supplies.

It's not known how much of the removed nitrates are being returned because operators of most of the systems say they don't keep track.

Some levels of nitrates occur naturally and are in the foods we eat. But health problems can occur when the chemicals are elevated, frequently attributed to high levels in water. Some of the sources cited in nitrate spikes in water include sewage or leaking septic tanks, runoff from fertilizer use and the natural erosion of nitrate deposits.

The U.S. Environmental Protection Agency mandates that water suppliers monitor drinking water for the chemicals, limiting nitrates to no more than 10 milligrams per liter. Sixteen municipal water utilities in Iowa have nitrate removal systems, spending millions of dollars each year to comply with federal drinking water standards.

The utilities are allowed to put the removed nitrates back into the state's waterways because they are not considered to be net generators of the chemical.

"You have to have a permit for treating water and then a different permit for what (chemicals) you emit, but in the case of nitrogen — at least at this point — it's kind of considered a no-net gain," said Kevin Baskins, a spokesman for the Iowa Department of Natural Resources.

Cities: We're concerned but options are limited

Nitrates not only increase health risks in humans but also contribute to the so-called dead zone in the Gulf of Mexico. Midwest fertilizers from 31 states that feed into the Mississippi River basin are often blamed for the problem, where algae blooms thrive off of nitrate-rich waters and make it difficult to sustain aquatic life.

The Des Moines Register in 2012 visited key parts of Louisiana and published a series of articles about the zone. The Register also explored efforts made by farmers, scientists, environmental groups and government agencies in reducing the runoff, such as planting a winter crop of rye to hold the soil and using wetlands to break down pollutants.

A few nitrate removal system operators told the Register they believe those efforts will help resolve their problems. But they also say their current options are limited.

Jon Martens, president of the Iowa Groundwater Association, called it a bit concerning that nitrates are being returned to Iowa waterways by municipal water utilities, "but I don't know what to do about it."

Martens, director of water operations for Atlantic Municipal Utilities, also oversees the city of Lewis' aquifer-supplied water system. Lewis has a de-nitrification system. The removed nitrates are pumped into two lagoons where they sit for around 180 days before being released into the Nishnabotna River.

While it's possible that some of Lewis' nitrates dissipate in the lagoon, the waste water isn't tested before it's released — so it's likely that much of the nitrates are being returned to Iowa waters, Martens said.

"You take it out of one source, and you dump into another source, and it's just weird to me," Martens said.

Des Moines has a detention basin where the mix of nitrates and a salt solution used in the de-nitrification process is pumped and diverted from being placed back into the Raccoon River.

But during high waters, the detention basin is full, and Des Moines Water Works has no other place to divert the nitrate solution but downstream and directly into the river. That resulted in the 13,500 pounds of nitrates being returned to the Raccoon last year.

So far this year, Des Moines hasn't run its de-nitrification system, but that could change as nitrate levels rise from spring runoff, Stowe said. Last year, the detention basin prevented roughly 26,300 pounds of nitrates from being returned to the river, Water Works officials estimate. The cost to water users was more than $500,000.

Winterset also has a lagoon system where nitrite-rich water is held for a week or so before being released to Cedar Creek. But water superintendent Steve Benshoof said he doesn't believe many of the nitrates are removed in that process. He doesn't like returning the nitrates to Iowa waterways, but said creating a natural nitrate filtration system would likely require millions of dollars in investments and tens of acres of land.

"Everything we're taking out is probably going back to the creek," Benshoof said.

Effects are cumulative, environmentalist says

Lagoon systems may remove nitrates if algae or other plant material is grown in them, but generally, the process doesn't greatly diminish the chemicals, said Bill Wilber, program chief for the U.S. Geological Survey's National Water-Quality Assessment Program.

The impact of Iowa municipalities releasing nitrates into waterways depends upon the amounts released. Small releases to large sources of water may have essentially no effect on the overall levels, but that doesn't mean it's harmless, Wilber said.

"Yes, some of it degrades but it's cumulative. Even some of that waste in small amounts from different municipalities in the waste water treatment plants in Iowa ultimately ends in the Gulf of Mexico," Wilber said.

The Gulf of Mexico's dead zone covered more than 5,800 square miles along Louisiana's coastline last summer, according to a survey at the Louisiana Universities Marine Consortium, a science-based group. That was more than twice the measured area the prior year and greater than the average size during the previous five years, the group's research shows.

Low oxygen levels in the zone kill organisms and reduce habitat for shrimp and many recreational fish species like red snapper.

Nancy Rabalais, the consortium's executive director, said some nitrates naturally dissipate as they move downstream.

"The total amount that goes in is not the total amount that comes out, but every addition contributes to what goes out," Rabalais said.

The Iowa chapter of the Sierra Club has tracked situations where untreated water bypassed state treatment facilities due to situations like floods, failed sump pumps and sewage leaks.

More than 500 such situations have occurred since 2007, some where hundreds of thousands of gallons of untreated water is released to waterways, the group's research shows.

Like runoff from a single farm, those individual situations may contribute only minute levels in comparison to the overall problem, but they nonetheless contribute to water nitrate levels and should be taken seriously, said Neila Seaman, director of the Iowa Sierra chapter.

Sierra supporters would prefer that water facilities not return nitrates to Iowa water systems, but Seaman also said they understand the issue is complex. Resolution will require a more holistic approach that involves science, as well as improved farm techniques and water treatment facilities or infrastructure, she said.

"Des Moines Water Works customers like me have to pay a lot more to take nitrates out. When they put the nitrates back into the water then it potentially costs cities downstream like Ottumwa a lot of money." Seaman said. "It's a cycle."

NITRATES 101

Nitrates are chemical compounds, sometimes naturally formed in foods like spinach, that are found in a normal part of a diet but can cause health problems when in excessive levels. They've been linked to diseases including leukemia and non-Hodgkin lymphoma.

DRINKING WATER

The major sources of nitrates in drinking water are runoff from fertilizer use; leaking from septic tanks, sewage; and erosion of natural deposits.

IS MY WATER SAFE?

When routine monitoring indicates that nitrate levels are above the federally accepted level, water suppliers must take steps to reduce the amount of nitrate so that it is below that level. Water suppliers must also notify their customers as soon as practical, but no later than 24 hours after the system learns of the violation. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health.

REDUCTION

Scientists and farmers continue to work on nitrate reduction studies or farm practices to reduce the amount of the chemical released into water systems. Some studies include such practices as planting fall ground crops to help maintain nitrogen-rich soil in place.

SOURCES: U.S. Environmental Protection Agency and Healthy Child Healthy World, a California-based advocacy group.

13,500

pounds of nitrates were

returned to the Raccoon

River last year

26,300

pounds of nitrates were prevented from being returned to the river by the Des Moines Water Works detention basin

$500,000+

cost of the de-nitrification system to water users