Ringing in a New Water Year

October 1, 2021

Scoggins Dam at Hagg Lake in 2016
Happy New Water Year! The 2020-21 water year — which began October 1, 2020 — washed away on September 30, and the 2021-22 water year has officially turned on the taps. While a calendar year ends a couple of months into the wet season, a water year follows the flow of the season.

The Tualatin River Watershed received 30.6 inches of rain this water year, as measured at the Hillsboro Airport. That's roughly 85 percent of our average annual rainfall of 35.9 inches— and more than we got in 2019-20. But what really stretched our region’s water supply this last water year was timing and temperature.

Much of the precipitation occurred from November to February, followed by a very dry spring that required CWS to start releasing stored water from Hagg Lake beginning in early May — the earliest date on record. CWS released more water during late June in response to the record-breaking heat dome, and continued those higher release rates through the summer.

The Tualatin River is a vital source of water for Washington County communities, crops and companies. To keep the river flowing and healthy in dry months, CWS releases cool water from Hagg Lake and Barney Reservoir. Scientists closely monitor the river to determine when more water is needed to sustain water quality, fish and wildlife. Cleaned water from CWS’ resource recovery facilities is also an important contribution to the Tualatin River’s flow during dry months.

“The recent rains have certainly helped,” said CWS Water Resources Manager Raj Kapur, “but the parched ground has soaked up that moisture and we haven’t seen a sustained increase in stream flows yet. Until the fall rains become consistent, our stored water releases and flows from our water resource recovery facilities will continue to be an important part of keeping the Tualatin River and its tributaries flowing, and improving overall water quality.”

As this new water year gets underway, are you — and your neighborhood storm drains — ready for rain?



Julie Cortez
Public Affairs Specialist - Content & Media
Clean Water Services
503.681.4453 (o)
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