1120 SW 5th Avenue, Room 1000, Portland, OR 97204
Many things cause drainage and flooding problems, including:
The city designs new roads and pipes to carry all stormwater from 96% of all storm, but the 4% of storms that are larger may create more runoff than some pipes can handle. The city designs the system this way to reduce the costs of building huge pipes that are only rarely used. Cities all over the U.S. build roads and pipes to similar standards.
Older roads and drainage systems not built to today’s standards
Drainage and flooding problems may be more frequent in parts of Portland that developed without proper drainage systems.
Many Environmental Services construction projects help reduce drainage and flooding problems. But the bureau needs to balance the amount of money available each year between those projects and maintaining and repairing aging sewer pipes and treatment systems, and meeting water quality permit requirements.