What is stormwater? and Why is it important?

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Stormwater is any precipitation (rain, snow, sleet, etc.) that collects on and runs off of land.  Even though Bend receives only about 12 inches of precipitation a year, stormwater can be a problem for the city and many of its residents.  

Short, intense rain storms can cause flooding and soil erosion.  Rain on snow events can cause water to pool up in the streets. In addition, there are some much less obvious but important problems having to do with pollutants carried by stormwater. As the stormwater crosses impervious surface areas-hardscape such as rooftops, driveways, sidewalks and street pavement-it picks up pollutants such as oil, trash, fecal matter, soil sediments, hard metals, pesticides or fertilizers.


Manmade impervious areas do not allow the water to sink into the soil as well as it would have under natural conditions. This results in more runoff. And because impervious areas do not have vegetation to take some of the energy from the water, the water actually moves faster. As the city urbanizes, this increased volume and velocity of runoff can stress surface drainages as well as our underground disposal areas.

Stormwater Disposal

Stormwater drained from Bend's paved areas and construction sites discharges with little or not treatment to the Deschutes River via a limited piped stormwater system or underground via underground injection controls such as drywells or drill holes. The attached map (LINK) depicts the public stormwater system, showing the piped system that drains primarily to Mirror Pond and the distributed system of drywells and drillholes. Not shown on this map and the hundreds of drill holes and dry wells located on private property.

A common misconception is that the soils throughout Bend drain water really well. In some places this is true, but in several areas throughout town there are natural impermeable layers of rock called welded tuff that prevent water from infiltrating far. Without a strong understanding of what exactly is underground, some underground systems have failed. The City is working to strengthen its requirements for geotechnical reports for new and redevelopments to provide a better picture of what the situation is underground.

The city's storm drains are intended to collect and convey only one thing-uncontaminated storm water. Anything that is spilled, dumped or deposited where it will be washed into the storm drain is a problem. 

What is the City doing about these issues?

  • City street crews conduct street sweeping operations and clean catch basins regularly. 
  • The City is working to meet its stormwater quality regulations and has prepared a five-year plan, the Integrated Stormwater Management Plan, to address water quality concerns. 
  • In addition, the City has embarked on an overarching Stormwater Master Plan, a comprehensive examination and plan for improving the city's stormwater system.


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