How is Your City Using Urban Forestry to Protect Creeks?

Urban creeks get hammered by erosion and pollution with every storm.  Polluted runoff goes directly from street to stream through storm sewers, carrying pollutants from rooftops, parking lots, streets and sidewalks at high velocities that erode stream banks and stir up old polluted sediments.

PCC Students Plant a Douglas Fir Tree in the
Sylvania Campus Parking lot to reduce runoff.
One way of reducing runoff is to plant trees.  Trees intercept rainfall on their leaves and branches and allow it to evaporate back into the air.  Tree roots provide a path for water to get through clay soils so rain can replenish the groundwater.  Leaf litter forms organic mulch and soil that acts like a sponge to soak up water before it becomes runoff.  Trees also provide shade to creeks, to keep the water cool for our native cutthroat and steelhead trout.

Some local cities and agencies are strategically using urban forestry to make creeks healthier.  The twelve member cities of Clean Water Services are participating in Tree for All, a program for planting native trees along creeks to keep the water cool.  The program is ahead of schedule for planting two million trees over 20 years.  Volunteerscan help out their city with planting projects from January through March.
Trees on upland areas also reduce runoff.  A healthy tree canopy can save a city significant costs in stormwater infrastructure.  Some cities have taken steps to protect their urban forests with ordinances, planting, and maintenance programs.  Metro has measured the amount of tree canopy in the cities within their jurisdiction, shown on the chart below.  The City of Durham tops the chart with 54% tree canopy!

Improvement from the status quo is always possible.  The City of Tigard recently adopted goals, ordinances and policies that will increase their tree canopy significantly from the current level of 25% up to 40% by 2047. 

Cities can get considerable support for their urban forestry programs from Oregon Department of Forestry (ODF) and other organizations.  ODF administers the Tree City USA program of the Arbor Day Foundation.  Tree City USA status is given to cities who comply with four standards. 

  1. A Tree Board or Department
  2. A Tree Care Ordinance
  3. A Community Forestry Program With an Annual Budget of at Least $2 Per Capita
  4. An Arbor Day Observance and Proclamation
These standards were established to ensure that every qualifying community would have a viable tree management plan and program and that no community would be excluded because of size.  Banks, Beaverton, Forest Grove, Lake Oswego, Portland, Sherwood, Tigard, Tualatin and West Linn have all earned Tree City USA status. The City of Tualatin has earned Tree City USA status for 26 years!  If your city is not on the list, start talking to your municipal staff, mayor, or city council about stepping up.