April showered us with a lot of rain—nearly a record amount for the month—but Eugene’s storm and sanitary conveyance systems were up to the task. Storms in the first half of the month dropped more than seven inches of rain, including 2.34 inches on Sunday, April 7. The heavy rains, coupled with dam releases and melting snow from the Cascades, brought a surge of water into Eugene.
The Willamette River and Amazon Creek quickly jumped their banks. Water flooded bike paths and parks and sent more than six times the normal amount of water through the Wastewater Treatment Plant. Despite the heavy flow, the systems mostly worked as designed without any sanitary sewer overflows (SSOs).
As the rains came, staff monitored catch basins and known trouble spots in the stormwater system. Crews responded to one location near the University of Oregon that’s prone to flooding, but there were no reports of property damage. They also created an inventory of sandbags, but they were never deployed in the City.
Flooding in Alton Baker Park (below) and the bike path near Amazon Creek were popular backdrops for social media pictures. Despite the significant increase in water, they served their purpose by adding to the capacity of the conveyance systems and moving water through town.
The Wastewater Treatment Plant also played a major role during the storms. The plant received a high total daily flow of 193 million gallons. The peak flow rate for April 7 came in at 222 million gallons per day (for context, the average daily flow is 30 million gallons per day). Despite the significant increase, there were no sanitary sewer overflows and everything was treated in full compliance with our discharge permit.
While Eugene’s systems have flooded and will likely flood again, the storms proved our systems were well designed with conveyance and capacity in mind. Our maintenance efforts continue to ensure we’re doing our part to limit damage, even under extreme circumstances.