Water Quality

Runoff from your property can carry pollutants to streams, rivers, wetlands, ponds, and lakes. The Federal Clean Water Act requires that surface waters meet water quality standards, and a plan to clean up the water must be developed and implemented if standards are not met. In Multnomah County most of the surface water does not meet the standards.

Water quality problems and impacts in rural Multnomah County
Warm water temperaturesLack of shade, in-stream pondsIncreases susceptibility to disease, reduces growth, decreases spawning success in trout and salmon.
High fecal bacteria countsAnimal waste, failing septic systemsIngestion by humans can cause gastrointestinal illness. Children are especially vulnerable.
Low dissolved oxygen levelsLack of shade, sediment, high nutrient levelsVery low levels affect survival of fish and other aquatic life; low levels increase susceptibility to toxins.
High nutrient levelsRunoff, over fertilizing, failing septic systemsCauses low dissolved oxygen levels.
ToxicsPesticide contaminated sediment in runoffPose a risk to human health through contact and fish consumption, to livestock through water consumption, and to the development and survival of fish and other aquatic life.

So what can you do to protect water quality?

  • Keep new buildings as far away from creeks as possible. This will help reduce erosion and flooding problems.
  • Keep a buffer strip of native trees and shrubs along the creek. Studies show that widths of 50 feet trap eroded soils, 100 feet filter pollutants, and 200-300 feet provide wildlife corridors.
  • Do not install rock, riprap or gabions along your stream bank. While these features may give your streamside a more landscaped appearance, they can reduce the water quality in your stream and damage your downstream neighbor’s property. If you have erosion issues, try planting native riparian plants.
  • Preserve the natural features of the creek. Fallen logs and meanders in the stream are essential physical structures that stabilize the stream. There is no need to clean up this natural debris unless it is threatening you or your property. If so, be sure to consult ODFW or the county before going to work.
  • Keep horses and livestock away from streams. They break down stream banks causing erosion, and their waste pollutes the water. Provide water for livestock at a small access on the stream or better yet, at a nose pump or trough in the pasture.
  • Do not divert a spring or creek to build a pond (even for irrigation use) without a permit. Ponds raise water temperatures, promote algal growth, tend to fill with sediment, and are very expensive to maintain. Impounding water without a permit is illegal.
  • Avoid filling ravines or slopes above creeks with dirt, grass clippings, or other debris. Storms will carry this debris down slopes and into waterways.

Remember, water flows downstream. How you treat the section of stream on your property affects water quality on your neighbors’ property downstream, just as the actions of your neighbors upstream affect you and your property.


Technical assistance and potentially cost share assistance are available to help you manage riparian areas and wetlands to protect water quality.  Give us a call or request a site visit.