Project B.6 Reduce Predation at Night-lit River Structures

Project has been Partially Completed

Bright lights shining into the water at night from bridges and other structures in the

Central Valley rivers, especially the Sacramento and its tributaries, create a significant predation hazard for salmon fry and smolts. These fish tend to move at night when they can avoid predators. When they encounter bright lights they become disoriented, stop to feed, and are easy predator prey.

One of the prominent problem bridges is the Sundial foot bridge which crosses the Sacramento River in Redding. Lowering the very bright lights on the bridge was advocated by the regional office of the California Department of Fish and Wildlife. The City of Redding partially cooperated and the intensity of the lights has been lowered at some times of year. Some have also been redirected away from the water.

The installation of lower intensity LED lights further lowered the light level while saving electricity. There are many other bridges and structures along the river that need modifications of this type.  With funding from the CVPIA restoration fund, a catalogue of problem night light spots on the Sacramento River was done in 2017.  GGSA calls for next steps including educating light owners and asking for voluntary compliance to reduce or redirect their lights away from the river.

Additional Resources

Recent study documenting affect of night lights on juvenile salmon

Fish Bio article on salmon and night lights