CWE evaluated the impacts of adding an invert access ramp to connect the Eaton Dam Spillway to the Eaton Wash Channel.  The Los Angeles County Flood Control District (LACFCD) wanted to add an access ramp to connect the spillway to the channel to provide accessibility for maintenance.  The modifications to the channel hydraulics required approval by the United States Army Corps of Engineers (USACE).  Two 2-Dimensional models, AdH and 2-Dimensional Unsteady Flow (TUFLOW), were required to ensure that the modifications did not impact channel hydraulics.  Existing and proposed conditions models were developed to assess maximum spillway and channel flow conditions.  The study also required determining the most critical combination of flows at the confluence of the channel and spillway.  A report was prepared and submitted to LACFCD and the USACE for approval of the channel modifications.  The study was approved and the project was constructed.