Why Augusta’s river level shouldn’t determine Thurmond discharge

(Editor’s Note: This post, written by Savannah District Deputy District Engineer Erik Blechinger, was published in the Augusta Chronicle Feb. 9.)

Over the course of several public meetings and feedback on social media there appears to be misunderstanding over what the fish passage legislation intends for acceptable river water levels in the downtown Augusta area.

Some insist the language in the Water Infrastructure Improvements for the Nation (WIIN) Act requires construction of a structure that will hold the same water level as existed in December 2016, which is the law’s date of enactment.

The exact language reads, construction of “a structure that is able to maintain the pool for water supply and recreational activities, as in existence on the date of enactment of this Act.” And the recommended fixed-weir design will accomplish this.

The law is correctly understood as constructing a project that will continue to enable water supply and recreational activities in the way in which the current pool did on the date of enactment. Note that water levels are not mentioned in the law. Nor would it be reasonable to suggest Congress knew the particular water level of the Savannah River on the date of enactment – and preferred the level on that day over the level on other days or weeks before.

Rather, the intent is to continue to provide the functionality of water supply and recreation as the New Savannah Bluff Lock and Dam did on the enactment date.

There is no other way to meet the intent of WIIN Act without deauthorizing the three upriver multipurpose projects: J. Strom Thurmond Dam, Richard B. Russell Dam and Hartwell Dam.

Let me explain.

The current pool level in Augusta exists under two causes: First, water held back by the New Savannah Lock and Dam gates; and second, water discharged from Thurmond Dam.

The first cause (lock and dam) will be replaced by a fixed weir, which is the most cost-effective solution to meet the intent of the law. The weir will hold back water, but we are unable to manipulate the level as we do with the lock and dam because the new structure will be fixed at a specific height with water passing over to provide fish passage.

There are two resulting consequences: First, we will be unable to mechanically increase channel capacity to accommodate high flows (therefore, it must be set low enough to avoid flooding impacts through the Augusta area); and second, we are unable to increase the height of the pool during low flows.

This leads to the second cause of the Augusta pool: discharge from Thurmond Dam. And since we have control of discharge, some would suggest we should maintain the Augusta pool at desired levels using Thurmond Dam.

So why not do this?

Even if the WIIN legislation was interpreted to mean the specific water surface elevation on the date of enactment, the physics of the river system would not allow keeping a pool of this kind at a static level. Specifically, releases from Thurmond Dam along with local stream inflows impact water levels of the Augusta pool.

We can control levels within a range, as we currently do with the old lock and dam; but keeping a static elevation is nearly impossible. The effort would require continuous manipulation of the releases out of Thurmond.

Currently the upper basin projects, including Thurmond, exist and operate under the authority of a number of laws passed from 1944 to 1986. These laws govern how we operate the structure.

Federal law directs that Thurmond’s water operations be managed to meet the intent of several purposes, such as flood risk management, hydropower, clean water supply, recreation and fish and wildlife preservation.

The volume, timing and manner in which we release water from Thurmond varies greatly in order to meet these purposes that serve a population of more than 3 million people, along with fish and wildlife throughout the Savannah River Basin.

If we were to make the water level in the Augusta area the primary guiding factor for Thurmond discharge, the fixed weir along with Thurmond Dam would become a “system” with water surface elevation in the Augusta pool becoming the dominant federal purpose of that newly created system. The new system would require abandonment of the congressionally authorized purposes of Thurmond and the other dams upstream.

There would be unintended consequences. I’ll list just three:

First, we would lose the ability to consistently delivery zero-emission energy to the region. The dams were designed to produce hydropower, which supply peaking power during times of high demand. Hydropower is only useful when we generate in spikes of discharge, based on peak energy demands at certain times of day.

Second, Thurmond and Hartwell water levels would be much lower most of the time, especially during the recreation season. The increased discharge volume needed to make up for the height of the fixed weir would be greater than inflows into the reservoir.

The result would be artificial drought conditions for the reservoirs. This would impact the 12.5 million recreational visitors the upper lakes attract each year. There are also 15,000 people with property and permitted docks adjacent to the shorelines who would be adversely impacted.

Third, Augusta’s single greatest flood-protection is Thurmond Dam. Since its construction under the Flood Control Act of 1944, Augusta has not seen a single devastating flood like the ones experienced decades before, such as the great flood of 1929.

This is not just because the presence of the dam, but the way in which we operate the structure. The purpose of flood risk reduction requires us to manage water in ways that would make it difficult to hold a specific pool level downstream in Augusta.

The bottom line is we balance our operations and operate the system to meet the multiple purposes authorized by Congress.

Based on the physics of the water system, the intent of the law, good stewardship of federal taxpayer resources, and the best interest and safety of all those who depend on the Savannah River for various fresh water needs – including those in the Augusta area – the recommended plan for replacing the obsolete New Savannah Bluff Lock and Dam is the best option available today.

About U.S. Army Corps of Engineers Savannah District

The U.S. Army Corps of Engineers Savannah District oversees a multimillion dollar military construction program at 11 Army and Air Force installations in Georgia and North Carolina. We also manage water resources across the Coastal Georgia region, including maintenance dredging of the Savannah and Brunswick harbors; operation of three hydroelectric dams and reservoirs along the upper Savannah River; and administration of an extensive stream and wetland permitting and mitigation program within the state of Georgia. Follow us on Twitter @SavannahCorps and on Facebook.com/SavannahCorps
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