Levees & Flood Control

graphic of levee cross section

Levee cross section. Click to enlarge.

A levee is a man-made structure, usually an earthen embankment, designed and constructed according to sound engineering practices to contain, control, or divert water flow to provide protection from temporary flooding.

There are 28.2 miles of levees along the Columbia River, Sandy River, and the Lower Columbia Slough system. These levees are made of sand placed on top of Columbia River alluvium (sand, silt, and other materials deposited offshore from the river). They are engineered to allow a small amount of water to seep through the levees into a drainage system that pumps the water away. This allows for flood control while also reducing the pressure on the levee to prevent failure.

Interior Drainage
The interior drainage system associated with the levee system is made up of ditches, pipes, culverts, pump stations, and storage areas that collect excess water from rainfall (stormwater) and seepage from the levee system. The water is collected through a series of ditches that feed into pump stations which drains the water into the Columbia Slough and Columbia River.

Pump Stations
There are 12 pump stations operated and maintained by the Drainage Districts.  Nine of the pump stations are owned by MCDD. Three pump stations are owned by other agencies and are maintained by MCDD.

Our 9 Pump Stations:

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