There are five creeks in Piedmont, all of which flow into Lake Merritt, and eventually, the San Francisco Bay. Bushy Dell is the main creek that flows through Piedmont Park.

The area became more urbanized in the early 1900s. By the 1930s, most of these creeks were culverted or channelized. They now flow largely through underground pipes rather than naturally above ground. A few above-ground segments (“daylighted”) remain in parks and some open-space corridors. Most of the daylighted sections of the creeks aren’t connected. Still, even when invisible, these creeks continue to shape our local ecosystem, carrying rainfall and runoff toward Lake Merritt and the San Francisco Bay and causing landslides and slumping on properties.

Undergrounding Piedmont’s creeks meant that houses could be more easiliy built, but it also caused long-term damage to the environment that’s visible today. These problems include (need citations):

• Creeks that aren’t permitted to flow naturally pick up urban pollutants more quickly (oil, metals, chemicals) and send them directly into downstream waters. Piedmont’s creeks are polluted (link to data)

• Pipes and unnatural channels raise water temperature, harming aquatic life. Piedmont’s creeks have unnaturally high temperatures (link to data)

• Hard-lined channels move water faster, damaging land around the creeks and causing landslides and even flash-floods downstream (link to photos)

• Underground creeks become biologically dead: no plants, insects, fish, amphibians, or birds that would normally rely on these creek corridors. This is true of Piedmont’s creeks (link to data)

• Tree loss along the creeks lessens natural cooling and shade, making neighborhoods hotter (“urban heat island” effect).

• Pipes stop creek water from recharging water aquifers.