Conclusions

As of April 1999, sand storage levels measured at our study sites are near those measured before the 1996 controlled flood. High- elevation sand bars have eroded to levels slightly higher than pre-flood measurements. Low elevation storage environments in eddies and in the main channel have recovered to approximately equal to pre-flood measurements.

The 1996 controlled flood resulted in widespread high-elevation sand bar deposition.

The 1997 test flow resulted in some high-elevation deposition of sand, however most of these sand deposits were rapidly eroded under high dam releases by April 1998.

In addition to sediment availability, the volume of sand occupying depositional sites prior to flooding is an important factor in determining the magnitude and persistence of flood related deposition.

The most efficient way to conserve fine sediment in the system is to release controlled floods that redistribute sand to higher elevations along the channel margins where it will remain in storage for relatively long periods.