As part of an ongoing series called “Follow the Flow” that examines Utah’s water future, this story examines how water managers in Utah are shifting their point of view when it comes to stormwater. New practices promise to reduce the pollution that stormwater brings, and turn stormwater into a resource that can help replenish parched lands.
With every storm comes stormwater that sweeps up anything in its path, including oil, grease, leaves, litter, fertilizer and what ever else accumulates on roadways, parking lots, and on our lawns. It washes down gutters and into underground pipes that deliver the gunk straight to our rivers and streams.
“The big problem we have with stormwater is that it’s not treated before it goes into the rivers,” says Jason Draper, a stormwater manager for Salt Lake City. “And so as water comes off the parking lot, it would go in a pipe and go in the river with whatever else is in the parking lot.”
In fact, half of the pollutants in our nations waterways come from stormwater runoff, causing civic leaders to rethink how they should deal with it. “Traditionally it’s been about flood control and getting water away,” says Draper. “Now we’re looking at this water as a resource and what we can do to clean it up. It’s an exciting time.”
Managers like Draper are looking toward the next generation of stormwater management practices called Low Impact Development (LID). It’s sort of a throw back to nature. The idea is to keep rain as close as possible to where it naturally falls, and let soils and plants do the hard work of filtering out pollutants as it seeps into the ground.
The U.S. Environmental Protection Agency has been promoting LID for years, but it’s been slow to catch on here in Utah, and the semi-arid West. “People have the perception that it doesn’t rain. Well, it does rain here, just during certain times of year,” says Christine Pomeroy, a professor of Civil and Environmental Engineering at the University of Utah. “We don’t get as much rain but it doesn’t mean that we don’t have pollutants accumulating on our surfaces that end up in the stormwater. So it’s still important.”
Planning for the urban future
LID projects are finally starting to pop up, even in Utah. Midway between Provo and Salt Lake City, the planned community of Daybreak offers a glimpse into the urban future. Along with light rail and solar powered homes, it has put it’s own twist on stormwater management.
When rain falls, stormwater travels through a series of gutters and above ground channels into common-use lawns that sink into swimming pool sized infiltration basins. Dry wells at the bottom of the basins act like drains that send the water deep underground, promising to replenish lands that have been parched in recent years.
Plus, the system catches nearly all of the stormwater runoff, keeping pollutants out of the nearby Jordan River.
Daybreak engineer Gary Langston says their system will save $70 million over the lifetime of the community, largely because they didn’t have to put much pipe in the ground. “For me, one of the personal things that I like about our stormwater system is that it keeps the stormwater where it landed,” says Langston. “Obviously with development we’re modifying the natural environment a little bit but it maintains the ecosystem in place as much as we’re able.”
Though their custom approach appears to work as planned, it isn’t a one-size-fits-all solution. “Storing the 100-year storm event doesn’t work for every project,” says Langston. “When you have the size of the development we have it makes a lot of sense. When you have a small 10-lot subdivision it probably doesn’t work for you.”
Rain gardens in the desert
Yet there are some LID practices that can fit nearly anywhere. These include green roofs, pervious pavement, rain barrels, and rain gardens. Originally designed to handle the soggy East Coast weather, scientists with the water research group iUTAH are now adapting them to cope with the unique conditions of the semi-arid West.
The University of Utah in Salt Lake City is home to some of these experimental gardens. One, nestled between a parking lot and brick building, is planted with clusters of bunch grass and rabbitbrush, bursting with pretty yellow flowers. Under crushed rock and topsoil is two-feet of gravel, which acts like a reservoir.
“What happens when it rains, the water goes to that gravel layer and fills that gravel layer during the storm and then after the storm slowly infiltrates to the soil below. Then during the summer these plants can root down, as far as 20 or 30 feet in some cases, to access that water during the summer, reducing your need for irrigation,” explains Dasch Houdeshel. He built the rain garden four years ago when he was a scientist with the water research group iUTAH.
By many measures, the garden is doing quite well. Unlike the lawn it replaced, it hasn’t needed sprinklers or drip irrigation in three years. “We’ve probably saved 37,000 gallons per year which is roughly one-third acre-foot of water since the garden was built,” says Houdeshel. That’s equivalent to one-half of a football field filled one foot deep with water.
But, Houdeshel acknowledges that more research needs to be done. He’s found that waterwise plants aren’t as good at extracting pollutants from stormwater runoff as wetland plants used in East Coast rain gardens. Plus, some are afraid that rain gardens may actually deliver pollutants to underground sources of water. “There’s just not enough known to be able to make certain recommendations about these designs and to ensure them,” he says.
Despite uncertainties, regional stormwater managers are excited by what they see. Salt Lake City Public Utilities has installed a demonstration rain garden on its property just east of downtown, hoping to promote the concept within the city and in private industry. “This is more expensive then just putting in traditional pipe. But in the long run when you factor in social costs, water costs, and any other costs that could happen if untreated downstream, it’s a big money saver. And it looks nice,” says Draper. Some studies show a long-term savings of up to 80%, over the traditional curb and gutter approach.
According to Utah State University social scientist Andrea Armstrong, it may not be long until practices like these are embraced on a wider scale across the state. She ran a statewide survey showing that half of the 70 cities who responded are implementing LID water management practices already, and the number of projects is growing.
“It’s ripe. It’s a really ripe area in Utah. Other semi-arid states are grappling with this as well. The seeds of these innovations are starting,” she says.
While ordinances that support or limit LID practices vary widely across the state, there seems to be a general feeling among stormwater managers that it’s only a matter of time before such practices catch on. “Once you start, it becomes perpetual motion after that,” says Trace Robinson, public works director with Riverton City. “Once you have a successful project, it’s something you can show others, and there’s a lot of those starting to show up.”
Rain garden at the University of Utah