Located along a narrow right-of-way in a highly developed urban area, the Berryessa Creek levees extend approximately 1.5 miles from the confluence of two creeks to a box culvert crossing of Calaveras Boulevard.  The levees were constructed in 1976 and raised in 1997 to provide 100-year flood protection based on hydrology and hydraulics at that time. Subsequent engineering evaluations identified slope erosion and cracks in the levees that could potentially lead to failure of some sections. The levees do not currently meet FEMA requirements. 

Winzler & Kelly was contracted by the Santa Clara Valley Water District to evaluate the levees for their ability to carry the projected 100-year flood flows and to develop alternatives and recommend a preferred alternative for addressing the levees' stability problems and flow capacity increase. The study phase involves hydraulic and hydrologic analyses, slope stability and protection analyses, and geotechnical and structural field investigations. Following the study phase, completed in December 2002, Winzler & Kelly developed alternatives for necessary improvements and recommended a preferred approach to improve the levees. 

The predesign study involved HEC-HMS and HEC-RAS modeling to aid in the alternatives analysis. The alternatives considered possible maintenance scenarios and ways to allow a natural meandering low flow channel within the levee section.

The Berryessa Levees project required coordination with an urban trail project for the City of Milpitas. The City engaged Winzler & Kelly to develop urban trail improvements and a pedestrian overpass on the levees.