Many communities in Washington State have observed a reduction in the level of flood protection provided by existing flood control facilities due to the accumulation of sediment in some river systems. Sediment deposition documented in recent decades and the reduction in flood conveyance in some rivers has been linked to several factors: a change in the hydrologic regime (both due to climate change and historical flow regulation), exposure of erodible material by glacial retreat throughout the Cascade Range, channel and floodplain modifications, increased sediment yields from historical land use changes, the cessation of the previous practice of gravel removal in some rivers, and natural aggradation consistent with long-term geomorphic processes.

The Washington Association of Floodplain Management (WAFM) has sponsored a Sediment Management Issues Group, composed of river managers, scientists, engineers, and other interested parties of diverse disciplines, to discuss issues regarding sediment and flooding, share information and experiences, and consider potential sediment management approaches. To that end, four topics have been identified for further discussion, and four groups have been formed to address the topics, as described below. These subgroups will certainly have overlap with their topics and interaction will occur between them which the flow chart below attempts to display. Although it is not known when or how the discussions about sediment management will conclude, it considered extremely beneficial to begin having this discussion together with many disciplines involved, rather than separately with very little progress to show for it.

Flow Chart for the Dynamics of the Sub-Groups

Future Meetings:

Meetings for the overall group will be on a quarterly basis.

The sub-groups, which are just now forming, will set their own frequency for meetings.