Santa Paula Creek is a major tributary to the lower Santa Clara River and is one of three main historical spawning tributaries for the endangered southern steelhead (Oncorhynchus mykiss). The creek holds approximately 18.5 miles of habitat historically accessible to steelhead (Stoecker and Kelley 2005). 

The record floods of January and February 2005 severely damaged fish passage facilities and caused major channel incision and bank erosion in the lower reaches of Santa Paula Creek, resulting in significant blockage of the upstream migration corridor.  Damaged and non-functioning facilities include the fish ladder at the upstream end of the U.S. Army Corps of Engineers channelization project in lower Santa Paula Creek, the Harvey Diversion fish ladder near the confluence with Mud Creek, and the Highway 150 drop structure near the confluence of Santa Paula and Sisar creeks.

The Santa Paula Creek Watershed Planning Project will:

• Develop a detailed watershed-scale hydrogeomorphic assessment as background to design of improved fish passage and diversion facilities
• Conducted focused studies of southern steelhead and resident O. mykiss behavior, habitat, and population to support the provision of adequate passage and expand upon knowledge gained in previous studies
• Develop viable engineered alternatives for restoring fish passage in Santa Paula Creek while maintaining existing diversion rights