Forecast Informed Reservoir Operations

Recognizing the connection between improved weather forecasting and reservoir operations, Yuba Water Agency plans to implement forecast-informed reservoir operations at New Bullards Bar Dam to significantly reduce flood risk on the Yuba River. This is now possible because of the recent and marked improvement in the science of weather forecasting. The National Weather Service can now accurately forecast rainfall amounts five days out, allowing water managers to predict flows up to a week in advance of a storm.

How it WorksNew Bullards Bar Dam and spillway with water being released down it

Implementing forecast-informed reservoir operations reduces flood risk and improves public safety by using weather forecasts to determine the optimal releases for a dam in advance of threatening storms. As an atmospheric river or 'Pineapple Express' storm approaches that is expected to impact the Yuba watershed, operators will determine exactly how much water to release in advance of the storm, while there is capacity in the river channel, thus creating room in the reservoir to store the storm flows. 

Currently, dam operators are required to keep the reservoir at a significantly reduced water level during storm seasons, ensuring space to handle possible storms, regardless of the forecast. 

Benefits of a Secondary Spillway

Implementing this new operational method at New Bullards Bar Dam requires the construction of a second spillway, with gates lower in elevation that the current spillway. If forecasts show a storm targeting the Yuba watershed, operators could create enough capacity by releasing water quickly with the new, larger spillway. 

Yuba Water Agency is currently designing that project, with completion scheduled for 2025. 

A graphic/rendering showing Yuba Water Agency’s planned secondary spillway at New Bullards Bar Da


Updating the Water Control Manual

Yuba Water Agency is working with the U.S. Army Corps of Engineers to update the water control manual, which guides storm-season operations of New Bullards Bar Reservoir. The agencies plan to release the new rules in conjunction with the completion of the secondary spillway.