Since the mid-1990s, HDR has been providing support to the U.S. Army Corps of Engineers for work at Folsom Dam. 

From 2013-2016, as part of a joint venture, we developed a Water Control Manual detailing the analysis of impacts to seasonal storage variations and how those impacts affected water supply, power generation and critical environmental factors, such as temperature, sedimentation, water quality, flows, spawning habitat and redd dewatering. 

The tasks for this project required the development, application and integration and documentation of computer models, utilizing ResSim and CalSim II hydrologic models, in an unprecedented manner. The fundamental purpose of the WCM update was to develop, evaluate and recommend to the United States Congress guidelines for the safe and efficient operation of Folsom Dam and Reservoir — resulting in a reduced flood risk to the Sacramento area. 

This WCM resulted in the recommendation of a Joint Federal Project including authorization, under the American River Watershed Folsom Modification project, of HDR to perform a Permanent Flood Damage Reduction Operations Study; Concrete Materials Engineering During Construction for the Auxiliary Spillway Control Structure and Dam Modifications; Hydraulics Design Review; and Engineering Design and Review Support for Dam Raise Gate Modification Project. 

The Folsom Modification project, in conjunction with the Folsom Dam Raise project, was reevaluated in the Folsom Dam Post-Authorization Change Report. This report resulted in the authorization of a JFP auxiliary spillway at Folsom Dam and a 3.5-foot dam raise, along with other flood damage reduction and dam safety features. 

For the Folsom Dam Permanent Operations Study, we evaluated the safe and efficient operation of Folsom Dam after the construction of the JFP auxiliary spillway. This effort required detailed analysis of impacts to seasonal storage variations and how those impacts affected water supply, power generation and critical environmental factors, such as temperature, sedimentation and water quality. This study also required the development, application and integration and documentation of control, hydropower generation, water supply and environmental impact computer models.