For those interested in how the planned fixed weir at the New Savannah Bluff Lock and Dam site will look along the Savannah River in the Augusta area – stand by. We plan to simulate conditions by making incremental adjustments to water levels beginning Feb. 9.
Originally planned for January, excessive winter rainfall required that we delay the simulation due to increased runoff in reservoirs above Augusta. The release of water from the flood pool has swollen the Savannah River in the Augusta area for the past three months. But now our engineers are confident the simulation can be safely conducted, weather permitting between now and Feb. 9.
After approximately five days of incremental adjustments at the lock and dam, officials expect to achieve target water elevations in the downtown Augusta area, on or about Feb.14, and hold at these levels for approximately seven days.
We’ve also synchronized the public release of the draft report to coincide with the simulated conditions. The draft report officially confirms the recommended plan, known as Alternative 2-6d, and discloses all our work, modelling and analysis. A 30-day comment period will follow the release of the draft report to allow the general public to review the report, observe simulated conditions and if desired submit informed comments. Savannah District officials will address each comment in writing, in accordance with the National Environmental Policy Act.
As part of the 30-day comment period we plan to hold an interactive workshop in the Augusta area where people can attend to learn more about the report through various stations staffed with experts, as well as provide comments either in writing or through dictation. The workshop will likely be held in early March.
We will announce the release of the draft report and finalized date of the workshop on this blog, so be sure to subscribe for email notifications.
Details on the Simulation
The pool adjustments will simulate the district’s recommended plan to maintain the function of the pool behind the current structure. Alternative 2-6d consists of removal of the current lock and dam and construction of a fixed crest weir with in channel fish passage and a floodplain bench. The fixed weir is expected to decrease the water level about 1 to 2 feet at the 5th Street Bridge gauge during average flow conditions in the downtown Augusta area.
It’s important to note that due to increased rainfall since November, river flows have been three to four times greater than average flow volumes causing the water level to remain about a foot above normal levels. Local residents may be accustomed to seeing water levels that are higher than normal for the last three months. Because of this the simulation may appear more dramatic than when compared to what is typically observed in downtown Augusta between June and October.
The simulation will also enable engineers to compare computer model projections of shoreline and depth with observed conditions of the simulation. The Corps created a Shoreline Mapping webpage where users can view Savannah District’s model projections of depth and shoreline at a river flow of 5,000 cubic feet per second, which is the low end of average flows. See the web tool here: http://water.sas.usace.army.mil/nsbld.
The recommended fish passage is an environmental mitigation feature of the Savannah Harbor Expansion Project, and is required mitigation in accordance with the Endangered Species Act. It is among the final seven proposed alternatives and refinements that the Corps studied under the direction of the Water Infrastructure Improvements for the Nation (WIIN) Act of 2016 to provide a means for certain endangered fish to move upstream of the lock and dam to traditional spawning grounds.
The study is scheduled for completion in June and the final decision is anticipated in August by the Commanding General of the Corps’ South Atlantic Division.
~Russell Wicke, Corporate Communications