While this article claims that sediment and vegetation will be removed from the
creek bed, remember that last time, several large trees were removed that were
a good 5 feet into the CCA on solid land not in the channel but in the CCA.
Please be on the look out and report any removal from the CCA because it
will increase the erosion along the banks of the park.  SUZ


Four Mile Run Channel Maintenance
Beginning in late June, Arlington County and the City of Alexandria will conduct maintenance work, including the removal of excessive vegetation and sediment along the Four Mile Run flood control channel. This maintenance effort is required to ensure flood protection for residents and businesses along lower Four Mile Run.
Background
The U.S. Army Corps of Engineers (USACE) constructed the Four Mile Run flood control channel, which extends from I-395 to the stream’s mouth at Ronald Reagan National Airport, in the 1970s following several devastating floods in the Arlandria area. USACE designed the flood channel to a width and depth sufficient to carry Four Mile Run’s flows during major rain events. Over time, sand and gravel build up in the channel, and plants grow on the sandbars, lowering the channel’s capacity for carrying the floodwaters produced by large rain events.  To ensure the protection of homes and properties adjacent to the flood control channel and ensure the structural stability of the flood protection measures, Arlington County and the City of Alexandria periodically must remove the sandbars and vegetation from the channel and in close proximity to the levees and floodwalls, in order to maintain the channel’s capacity for safely carrying floodwaters.  
What Residents Will See
Starting in late June, residents will see crews and construction equipment working in or near Four Mile Run, removing trees, shrubs, and other vegetation growing in the channel. Sand and gravel deposits may be removed in specific locations as well, depending on the amount of accumulation since the last dredging occurred in 2008.  While measures will be taken to reduce the amount of sediment that becomes re-suspended in the stream channel, residents may see some brown-ish discoloration of the water as sediment is removed and for a short period of time afterward.  The sediment and plant material may be temporarily stockpiled in locations adjacent to the stream before it is loaded onto trucks for recycling or disposal.  The herbicide, Rodeo, which is approved by the Environmental Protection Agency for application on invasive weeds and emergent vegetation along water bodies, will be used sparingly.
Future Plans
Arlington County and the City of Alexandria are working to limit the need for such maintenance in the future. The County and the City have partnered with the USACE and the Northern Virginia Regional Commission on the Four Mile Run Restoration Project, in an effort to return natural stream processes to the flood channel corridor, while also maintaining flood protection. The restored stream will reduce sediment deposition within the corridor and also will include vegetation appropriate for a flood control channel. The current channel maintenance activities relate to an existing maintenance agreement with USACE and not the restoration project.
Additional Information
For more information about the Four Mile Run Restoration Project, contact Laura Grape (NVRC - 703-642-4625),  Jason Papacosma  (Arlington County),  or Craig Perl  (City of Alexandria).