Portland's pretty green. But it could be even greener.

The City's Bureau of Environmental Services' goal is to minimize pollution that runs off our urban streets and into our rivers. Rainwater picks up a lot of gunk as it flows from city streets towards rivers.

Trees help collect this stormwater and the pollutants that are in it, holding them in place instead of sending polluted water flowing into rivers (and killing fish) every time it rains.

The larger the tree, the more stormwater it can manage.

To encourage tree-planting (and specifically, planting of the best kinds of trees for the purpose of stormwater management), Portland's Department of Environmental Services is offering a financial incentive to Portland residents who plant trees in their yards.

Treebate is a seasonal program available September 1, 2012 through April 30, 2013, coinciding with the best time of the year to plant tree. You purchase a qualifying tree, plant it in your (Portland) yard, fill out the application form and include your purchase receipt, and - if approved - you receive a Treebate. Easy!

A complete list of eligible trees, tree sizes, credit calculation methods and more can be found here. Note that while most tree species are eligible for a Treebate, not every tree will be eligible. Check and make sure before purchasing a tree!