Editor’s Note: This article is authored by Oscar P. Flite III, Ph.D., CEO and senior scientist at Phinizy Center for Water Sciences. Flite and his organization are involved in scientific research on the Savannah River that provides critical information needed to make informed decisions about the basin’s natural resources.
In order to make sure there is enough water to support a healthy river ecology and thriving economies along the Savannah River, water resource managers are always in need of high-quality information that will allow them to make better decisions so they can provide the balance between ecology and economy.
This spring, Phinizy Center scientists will begin a study to examine the impact of various flows on the aquatic life in oxbow lakes found along the Savannah River downstream of Augusta.
Oxbow lakes are remnant sections of river channels that have been cut off from the main river flow. These remnant sections are created naturally in lowland rivers as a result of erosional processes where a narrow strip of land is surrounded by water on three sides.
Over time, the river erodes both sides of the land creating a shortcut and leaving a section of old river channel. This channel, or oxbow, is initially connected to the river via surface water but over time can become disconnected and filled as a result of sediment transport and deposition.
Shown here, an owbow lake (left) and soon-to-be-oxbow lake. Oxbow lakes are remnant sections of river channels that have been cut off from the main river flow. (Courtesy photos)
Research on oxbows around the world has revealed their important role in supporting healthy rivers. Studies have shown many more algal, zooplankton, mussel and fish species live in oxbows compared to the adjacent river. Other studies have indicated that oxbow lakes are essential to the health of the river fisheries, providing abundant food resources and essential nursery habitat for juvenile fish.
In an effort to straighten and shorten the Savannah River for commercial navigation, the U.S. Army Corps of Engineers created many oxbows by cutting through wide river meanders. These shortcuts were generally developed in curved areas of river that were too sharp for many of the large commercial vessels to navigate.
The shortcuts were created by dredging a new river channel through a small strip of land that the river ran along both sides of, much like the natural oxbow creation process. From the 1950s to the 1970s, a total of 37 navigation shortcuts were completed, shortening the Savannah River by about 40 miles.
The oxbow research will involve several components.
First, scientists will assess the connectedness of many of the oxbows between Augusta and Savannah using high-accuracy GPS survey equipment. Next, they will monitor surface and groundwater levels in four oxbows, two that are still connected to the river by surface water, and two that are disconnected.
Then, Phinizy scientists will monitor water quality and analyze water samples for nutrient, algae and zooplankton levels. Lastly, the researchers will periodically examine the fish communities in these oxbows.
Perhaps most interestingly, some fish in one connected oxbow will be outfitted with tiny radio tags that will allow researchers to monitor their movements between the river and the oxbow.
Phinizy Center scientists will perform this oxbow research in collaboration with scientists from Clemson University, Georgia Regents University and Georgia Southern University. The one-year project is being funded by a competitive statewide research competition offered through the South Carolina Water Resources Center at Clemson University.
Results from this research should be available sometime in the spring 2016 and will be presented at the South Carolina Water Resources Conference.
We will also communicate results via Phinizy Center’s website and social media sites. You can follow the progress of this project on our Facebook page.
This is a prime example of a study where input is needed from Lake Interests as well as fish and wildlife and similar groups. Let’s say the study indicates more river flow would help some oxbows. That can be provided by more dredging which caused the departure from nature or increased releases from Lake Thurmond. Assuming nature does a good job with the exception of the ravages of extreme drought or heavy flooding, all you need once dredging problems are corrected is to release the same amount of water nature provides by rain except in extreme drought or heavy flooding. That gets us back to where nature is in control. Assuming more water is needed than nature provides can lead to bankrupting the lakes and thereby damaging the whole system.
The lack of representation of lake interests in interpreting measures needed from river studies has led to destructive practices in our current drought plans. Some may not agree with my interpretation of destructive practices. Lake interests who have seen the devastation to the recreational infrastructure around the lakes in the past 3 or 4 droughts will appreciate the fact that the current drought plan has been destructive..
Agreed, Jerry. The incredible amount of run off we see every time the lake is lowered is crazy. After a heavy rain we will see 6″ mounds of soil, carried from the now exposed bottom, out into the lake. My cove has lost about a foot in water depth in 9 years at the end of our docks. All the COE shoreline plantings and trees cannot stop the shore from eroding when the water is dropped and the shallow edges of the lake bottom are exposed and washed out into the center of the cove. Chasing water is no longer an option. We cannot move our dock out far enough to get 3′ of water, because the runoff has created 24″ of mucky mess. There has got to be a better plan.
I agree 100% Jerry. All of the environmental concerns seem to be focused on the lower Savannah. This month, because we have water in our cove, we are daily watching fish spawn in the reedy shallows, we have seen a bald eagle, beavers, muskrats you name it. Soon the cove will be full of bull frogs, water snakes and spawning bass and crappie. I’m old enough to remember what the Keowee and Seneca River basins were like prior to the building of the impoundments….this was quite an ecological wonderland. It seems as though they want to treat the upper basin area as though it is so far gone that no one should care about environmental concerns here. I predict that the end result of this study will be that the lakes need to release more water in unnatural quantities that will keep the unnatural, manmade oxbows well hydrated.
What is the project budget total? Who is paying for it?
I looked at the satellite and it looks like many of these ‘lakes’ are out in the woods or in swampy areas. There doesn’t seem to be any comparison to the development of the big SRB lakes
Fish1, et al: USACE did not sponsor or request this study. As far as I can tell it was funded by the South Carolina Water Resources Center at Clemson University. We merely asked Dr. Flite if he would be willing to write a guest post about this research because it is connected to our basin. It’s not otherwise connected to a Corps initiative. Hope this helps. ~Russell