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Seeking Clarity On Storm Runoff

Ed Williams
Stormwater flowing into the Rio Grande from the Tijeras Arroyo south of Albuquerque

It’s a peaceful scene on the banks of the Rio Grande south of Albuquerque, with ducks paddling on the slow moving current and the breeze rustling the willows at the water’s edge. But not all is well with the river, says Rich Schrader of the conservation group River Source. He’s out analyzing water samples with students, and there’ve been some troubling results—mainly, the turbidity, or murkiness, of the water.

"What we found is that in Rio Rancho the turbidity was about 60 ntu’s, and down here it was 143 ntu’s. That’s almost a threefold increase in turbidity between here and Rio Rancho," Schrader said. "So there’s got to be some source of turbidity coming from between here and the south side of Albuquerque."

Recent rains have made this the wettest spring New Mexico has had in years. That's good news for the drought, but storm water can also wash dangerous levels of pollution into the Rio Grande. And there's a lot we don't know about what pollution in the river means for public health.

The most likely culprit? Water from rainstorms and melting snow flowing into tributaries around the Rio Grande, picking up sediment, farm fertilizers, bacteria and whatever else, and washing it all into the river.

But pretty much the entire stretch of the Rio Grande running through New Mexico is in violation of water quality standards—for things like E. Coli contamination, PCB's, even radioactivity in the water. And most of that pollution gets washed into the river during storms, like the unusually strong rains that hit Albuquerque in early May.

This kind of pollution is enough of a concern for water managers that cities like Albuquerque and Santa Fe shut off drinking water intakes from the river during big rains to keep contaminants out. And there’s good reason to avoid the river after storms, according to a recent report by the U.S. Geological Survey.

Researchers there found high levels of E. Coli in Albuquerque’s stormwater, as well as chemicals calledPAH’s, that have been linked to cancer. They also found that levels of suspended solids, phosphorus, and bacteria in Albuquerque’s storm runoff are higher than in much larger cities like Denver and Phoenix.

Credit Ed Williams
Stormwater drainage on Kirtland Air Force Base

"There is a standard, it gets violated every time it rains," said Bruce Thompson, Professor of Civil Engineering at the University of New Mexico. He says a lot of pollution probably comes from natural sources like bacteria from animals and metals in the soil. But people in the city are contaminating stormwater, too—the problem is, the pollution varies so much from storm to storm that researchers haven’t been able to figure out where it’s coming from.

"One storm the water quality is really poor, the contaminants are sky high, the next storm it’s really good. It doesn’t make any sense," Thompson said.

Part of what makes understanding stormwater contamination in New Mexico so hard is that 93 percent of the tributaries in the state have not been assessed for pollution by environmental officials. That’s led to a lot of mysteries in terms of what kind of pollution is coming from where.

And Rachel Conn of the river watchdog group Amigos Bravos says what has been measured shows some concerning results.  

"More than half of the assessed streams are showing up not meeting one or more of the standards that apply. So, we do have a large water quality problem in here in New Mexico," Conn said.

The New Mexico Department of Health has not studied what the impacts of this pollution might be. To make things even more complicated, many of the state's streams and tributaries are not covered by the federal Clean Water Act. But that might be changing soon—this week the Environmental Protection Agency announced a new rulethat it says will protect more streams and prevent pollution in drinking water sources like the Rio Grande.

Credit Rashad Mahmood via Google Earth
Map of streams the New Mexico Environment Department has assessed for pollution. Assessed streams are in yellow.

Ed Williams came to KUNM in 2014 by way of Carbondale, Colorado, where he worked as a public radio reporter covering environmental issues. Originally from Austin, Texas, Ed has reported on environmental, social justice, immigration and Native American issues in the U.S. and Latin America for the Austin American-Statesman, Z Magazine, NPR’s Latino USA and others. In his spare time, look for Ed riding his mountain bike in the Sandias or sparring on the jiu-jitsu mat.
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