Anadromous Fish Restoration Program

Instream Flow

What is Instream Flow?


Instream Flow Habitat Sampling Site
FWS Photo

In 1995, the Sacramento Fish and Wildlife Office began a series of studies to identify the instream flow requirements for anadromous fish within the Central Valley of California.

With funding from the Central Valley Project Improvement Act, instream flow studies have been completed on the Sacramento, American, Yuba and Merced Rivers and Butte Creek, and are in progress for the Stanislaus River and Clear and South Cow Creeks.

macroinvertebrate processing

SCUBA diving to collect deep water
juvenile habitat suitability data
FWS Photo

In 1999, the Sacramento Office began additional studies to evaluate the effectiveness of restoration projects on Clear Creek and the Merced River. These efforts were expanded in 2009 to provide scientific information to other Central Valley Project Improvement Act programs for use in assessing fisheries restoration actions.

These actions included fish screens at Red Bluff, gravel additions on the American River, and Central Valley Project Improvement Act dedicated water used to reduce redd dewatering on the Sacramento and American Rivers and Clear Creek

The ability of a fish to spawn and rear young to survive is dependent on the volume of water flowing within the creeks and rivers. Too little flow at critical times could cause salmon eggs and young to become stranded and die. Too much water and the eggs and young can be washed away during a flood situation.

At present, our staff are:

Redd Dewatering Measurement

Redd Dewatering Measurement
FWS Photo