Before the houses came, water rarely flowed through Chalk Creek in Northwest Reno. Then, in the mid-2000s, new developments added lawns, a school, a golf course. People moved into the houses and began washing their cars, watering and fertilizing their grass, sweeping their leaves into storm drains. Chalk Creek began to flow year-round.
But the water flowing through it is brimming with nitrogen, phosphorous, sulfate-heavy salt—with year-round levels 10-100 times higher than that found in surrounding creeks. Those nutrients and salts enter the Truckee River, the region’s main drinking water source.
“The nitrogen and phosphorous we put on our grass and trees and gardens—our over-watering carries those off the sidewalk, onto the curb and into the river,” says city of Reno hydrologist Lynell Garfield-Qualls.
The city will hold its first Urban Watershed Awareness Day on Aug. 27. Volunteers will meet at the Purple Bean at 8 a.m. before going out into northwest Reno neighborhoods to stencil storm drains with “No Dumping” messages and to disperse information. Then on Aug. 30, the city and the Northwest Neighborhood Advisory Board (NAB) will unveil new interpretive signs for the Chalk Creek Sulfate-Reducing Wetland.
Garfield-Qualls says aerial photographs from 1986-2006 used bright pink to indicate areas of water. “In 1986, there was almost no pink at all in the photograph,” she says. “There was no water in Chalk Creek to support vegetation. Then you look at 2006. … Suddenly, you can trace the pink lines down the stream. Suddenly, the creek is running year-round.”
That may not have been so bad, except that the soils of the Chalk Creek watershed contain Hunter Creek sandstone, which leaches salt when water runs through it. And it doesn’t help that polluted water is flowing through it.
“So we have natural salts but artificial transport just through irrigation,” says Garfield-Qualls. “It comes out super salty and super high in nutrients.”
Just downhill from Rainbow Ridge Park, pockets of cattails and tall grasses attempt to counteract some of this with a wetland, funded by the Truckee River Fund and Northwest NAB. As water filters through the wetland, microorganisms in the soil eat the sulfates, producing hydrogen sulfide gas. The gas, which smells like rotten eggs, evaporates or is carried by the wind, removing sulfates from the system. Meanwhile, nearby cottonwoods and willow trees take up the nutrients the water is better off without.
“So nutrients are being taken up by the plants, and the salt is being taken out by the bugs,” says Garfield-Qualls.
While the bugs are hard at work, residents can also minimize their impacts. First, understand that, unlike some cities, Reno doesn’t have a separate storm drain system leading to a water treatment plant; if it goes in the storm drain, it finds its way to the Truckee. Also, reduce use of chemicals, like fertilizers and pesticides. Consider xeriscaping and using drip irrigation. Residents in the Chalk Creek watershed are encouraged to wash cars at a car wash rather than their homes. Reevaluate home watering times; try watering in short, frequent intervals, like for five minutes three times a day.
“Our crown jewel of the city is the Truckee River,” says Garfield-Qualls. “It’s smart in a lot of ways to think about what we’re putting on the ground, in our drinking water, and what we’re putting in our river.”