Concrete Rivers

Check out the channel in front of you and the map attached to guess why the treatment of Sausal Creek varies from an engineered channel — or concrete riverbed — to an underground culvert through much of Lower Fruitvale. During the alteration of Sausal Creek in the 1930s and 40s, people started prioritizing urbanization over creek health. This would often force the creek underground into large pipes or culverts to create room for lateral roads, including the 580 Freeway, East 27th Street and Foothill Blvd.

Engineers then observed that culverts sped up water and worsened flooding downstream. In downstream areas like Lower Fruitvale, engineered channels spaced out between major road culverts slow the water flow. Today, we understand that channeling water only between culverts worsens erosion and speeds up water velocity because smooth concrete does not allow water any time to seep into the soil.

Now, experts advocate for "slow, sink and spread": slowing water by building up sediment through building natural dams, and removing concrete to allow water to disperse and spread into the soil. Removing concrete does not just slow water velocity, it also creates a healthier habitat for macroinvertebrates, along with more carbon recycling, sediment transport, and habitat provision for other animals. However, this is a difficult task in urban areas like these, because people have built their homes adjacent to the concrete channels.