Stormwater Division

Stormwater Runoff


Stormwater runoff is the water that flows off City sidewalks, streets, and other hard surfaces during rainstorms. The runoff is collected in ditches, culverts, catch basins, and storm sewers.

In areas with natural ground cover, only 10% of rainwater becomes runoff. The rest is absorbed or evaporates. In urban areas, up to 55% of rainfall can become storm water runoff.

A storm drain maintenance program is required to ensure that ditches, culverts, catch basins, and storm sewers are kept clean of sand, silt, and other debris that may plug the system.

You Can Help


Citizens of the community can assist in keeping the storm system running by following a few guidelines:
  • Don't litter! This means you should never throw any trash on the ground. When it rains the litter washes into the storm drains.
  • Keep your leaves and grass clippings out of the streets so that they do not end up washing into the storm drain inlets.
  • Lawns need less than an inch of water per week. If it rains an inch, do not water. Water that runs off yards goes to storm drains.
  • Never dump anything down a storm drain inlet.
  • Wash your vehicles on your lawn or at a car wash facility instead of in your driveway.

Reporting Discharges


To report a suspected illicit, discharge in Selah, Sunnyside, Union Gap, or the County, call (509) 574-2300 or email

Learn More


To learn more about stormwater check out the Regional Stormwater Management Program.