To reduce your watering demand, you can design your landscaping with plants that consume less water. See a helpful guide prepared by EWEB and partners,
Water-Efficient Plants For The Willamette Valley.

water-efficient-plants-for-willamette-valley.pdf

The best way to determine your sprinkler system output is to use a watering gauge and ruler to conduct the following test:

• Place your older Green Grass Gauge or a DIY Watering Gauge in an area of the lawn where it receives a typical amount of water.
• Move the gauge around the lawn area between each watering cycle to help identify dry spots.
• Do not place it under trees, shrubs or other plantings.
• If you want to water twice a week, use the two-day a week watering recommendation. If you want to water three times a week, use the three-day a week watering recommendation.
• Run the sprinklers until the watering gauge is filled to the ​weekly watering recommendation​. Emptying the gauge between each watering cycle will help you to know if you are watering the recommended amount each time the sprinklers run.
• You may click the link above to see the weekly recommendation and you have the option at that link to sign up for a weekly Thursday email. (We also post this information on Rainbow's Facebook page.)