Arroyo Seco

Arroyo Seco Ecosystem Restoration Program

Here are the alternatives being considered for each reach:

NumberNameActions ConsideredRiparian Acres Restored
Reach 1Hahamongna BasinNo action0
Reach 2Flint Canyon WashRemoval of invasive species0
Reach 3I-210 near Oak Grove (between Devil’s Gate Dam and Brookside Park)Natural bottom with invasive species removal0
Reach 4aBrookside Park North (to the Rose Bowl)Flood plain benching and flood plain benching with pools for aquatic habitat;52.1
Reach 4bBrookside Park SouthLow flow channel with natural bottom;8
Reach 5aLower Arroyo Park North (Colorado Street Bridge to La Loma Bridge)No action, flood plain benching;19
Reach 5bLower Arroyo Park South (to SoPas border)No action, low flow stream with natural bottom;1.6
Reach 6South PasadenaLow flow channel; flood plain benching; RCB with Low-Flow Stream;46.5
Reach 7aArroyo Seco North (in Los Angeles)Low flow stream with natural bottom; RCB with Low-Flow Stream;2.5
Reach 7bArroyo Seco SouthNo action; Low flow stream with natural bottom; RCB with Low-Flow Stream;4.8
Reach 8Sycamore Grove ParkNo action; Low flow stream with natural bottom;1.4

Total Potential Acres Restored: 135.9

Key Definitions

Flood Plain Benchingfull stream restoration; flood channel removal
Low-Flow Streama natural bottom stream near the flood channel
RCB with Low-Flow Streamlow-flow natural bottom stream with flood overflow in a buried concrete box culvert
Habitat Unitsa measurement of the ecological value that a restoration project produces

Frequently Asked Questions | USACE Ecosystem Study