Concerned about her Portland home's stormwater runoff, Angie's List member Kyenne Williams asked the city to check her downspouts in preparation for more extensive landscaping this spring.

Williams says the city disconnected the home's downspouts 10 years ago, and now it's rerouting her gutters for free under the downspout disconnection program. She also plans to install a cistern in her backyard to collect rainwater that she'll use for watering plants.

"Once the gutters are rerouted, the cistern is ready to go in, and this spring, I'll put a rain garden in the front yard," says Williams, who hired The Rainbarrel Man, not yet rated on the List. "It seems really sad to waste water, and this is an attractive way to use the water."

Williams is one of thousands of Portlanders to take advantage of city initiatives designed to reduce stormwater runoff and keep local waterways free of pollution by offering incentives for adding natural features that filter stormwater on their property.

Portland adopted its five-year Grey to Green initiative in 2008 to encourage residents and businesses to plant trees and native, non-invasive vegetation, or install eco-roofs. The city offers a "treebate" water utility credit of $10 to $50, depending on the tree size, for each tree planted on residential property between September and April. In addition, for every square foot of eco-roof installed, residents and businesses receive water bill discounts.

"Stormwater either flows into the sewer system, where it has to be managed and treated, or it goes straight into creeks and rivers, where we've got endangered salmon and water quality problems," says city stormwater specialist Emily Hauth. "The most cost effective thing you can do on your own property is plant a tree and manage stormwater off your roof and driveway with landscaping, such as a swale or rain garden."

Williams says she's noticed more rain gardens in her neighborhood, which she attributes to Portlanders' eco-consciousness.

Micha Sinclair, co-owner of highly rated Rejuvenation Artisans Landscapes in Portland, says swales use plants and hardscaping to divert water away from homes and sewers. However, he says improper planning and soil testing can lead to problems. "You don't want to add more water on sites where erosion is bad," he says. "It may potentially cause damage to your foundation."

He says no system works on every property, so ask a professional landscaper with stormwater management training or a certified horticulturist for help in choosing the best plants for your yard. The cost for landscaping that focuses on stormwater control ranges from $1,800 to $5,000 on average, he adds.

Co-owner Grace Constantine-Sinclair recommends April and October as the best time to plant because it's not too wet to dig or too dry for plants to survive without extensive watering.