Legislation sponsored by a rural Washington lawmaker aims to improve the quality of life in the state’s urban communities by encouraging utilities to engage in tree-planting efforts.

House Bill 1114, sponsored by Rep. Mary Dye, R-Pomeroy, passed the Washington House and Senate unanimously and now awaits the governor’s signature.

Besides encouraging electrical utilities to adopt tree-planting programs, the measure authorizes the Washington Utilities and Transportation Commission to approve financial incentives for investor-owned utilities that offer such programs.

The intent, Dye said, is to reduce the negative effects associated with urban heat islands, thereby improving the environment and quality of life for urban residents.

The term “urban heat island” refers to the higher temperatures that occur in areas where natural vegetation and soils have been replaced by sidewalks, pavement, buildings and other heat-absorbing materials and structures.

This built-up environment essentially creates human-made canyons that absorb heat, release it slowly and raise overall temperatures, Dye said. Downtown Seattle, for example, “can be as much as 17 degrees warmer than the surrounding countryside, and the median difference is 4.1 degrees.”

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In 2014, Climate Central, a New Jersey-based climate science news organization, ranked Seattle 10th in the nation for its urban heat island effect.

Dye said that not only drives up utility costs for residents by increasing demand for air conditioning, it increases the amount of storm water runoff, because there are more impermeable surfaces. The runoff is warmer, as well, which promotes algal growth and makes Puget Sound a less healthy environment for salmon and other native species.

HB 1114 encourages tree-planting as a means to provide shade, absorb runoff and provide a more natural environment for urban residents. It’s modeled after a similar program in Sacramento, Calif., which has resulted in more than 600,000 trees being planted since 1990.

In 2015, the Sacramento Municipal Utility District estimated the trees could save customers as much as 40 percent on their summer home cooling costs.

“The trees are working and they’re saving a lot of power,” Dye said.

HB 1114 is part of a broader, longer-term plan Dye has to create “salmon-safe communities” by using trees, permeable building materials and other means to reduce toxic runoff and improve salmon habitat.

“This is a great first step, but my hope is we’ll continue to talk about (that broader effort),” Dye said.