Replacing, not repairing, New Savannah Bluff dam is clearly best choice

By Frank Carl, PhD

 

Guest Columnist

In the debate surrounding plans for the New Savannah Bluff Lock and Dam, it appears there are two approaches being posed: repair or replace.

Repair advocates want to redirect the flow of the river for most of the year through a fish ladder to be built on the South Carolina side, also suggesting repair of the dam and the lock.

The replace advocates want to remove the dam and replace it with a rock weir that would double as a fish passage, and repair the lock to allow for navigation.

Let’s start with a review of the recent history of the issue.

The dam was completed during the Depression era to provide jobs and facilitate commercial traffic on the river. But that commerce, doomed by the railroads, was dead by 1979.

Since the dam no longer functioned for its original intent, the Corps could not justify expenditures for upkeep and it fell into disrepair. The Corps wanted to remove the dam, but the cities of Augusta and North Augusta, concerned about pool level, objected. So, Congress authorized rehabilitation of the dam in 2000, but for 17 years refused to fund those repairs. Local governments made no serious attempts to fund repairs either.

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In recent years, advocates from our community successfully lobbied for legislation that required preservation of the current pool level and established that replacement of the dam be a viable alternative to its repair, a win-win for the CSRA.

As part of the Savannah Harbor agreements, the legal commitment by the Georgia Ports Authority to build the fish passage requires that work begin on that project before dredging can start in the harbor. Squabbling over plans for the Lock and Dam has had the effect of delaying that start.

The dam repair option requires funding, but no source has been identified for that activity. City leaders insist they’ll figure it out; we can assume what that means for the taxpayer. Given that funding for repair has been the holdup for the past 17 years, it is unlikely that it will be identified so quickly that project won’t be stalled. How long will Georgia Ports Authority be willing to wait while we try to identify repair funding that satisfies all parties?

The only unfunded part of the replacement option is the repair of the lock. The Corps is willing to remove the dam, and has been for some time, and the Georgia Ports Authority is willing to fund the fish passage. Are the cities willing to come together to fund repair of the lock, a recommendation from both advocates for repair and those for replacement?

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While the Corps has several models for the dam repair option, all of them include a diversion wall to direct the water to a new channel on the South Carolina side. Up to a flow of about 8,000 cfs (cubic feet per second) – flows most of the year are less – nearly all of the water would proceed through the fish passage. Higher flows, those between 15-30k cfs, are what damage the dam. It is just a matter of several repeated assaults by floodwaters before it fails. At that time, the pool would disappear, leaving flows of 3,600 cfs or more, but no lake.

As for concerns over flood control capability, the dam itself has never been used, nor was it designed, to control flooding. A much better approach for the CSRA is to provide sufficient storage capacity in Clarks Hill Lake. Indeed, it is one of the primary reasons Clarks Hill Dam was constructed.

In addition to the probable delay, the repair option suffers from other disadvantages. Diverting the entire flow of the river to South Carolina will create significant dead water zones around the current dam site. These zones would be still and deep, dissolved oxygen would be low and fish would avoid it. Local fishing at Lock and Dam Park would be degraded.

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In contrast, the replacement option would simply create rocky shoals in place of the dam, functioning as a fish passage and eliminating the need to divert the flow to South Carolina. As water flows over the shoals it becomes oxygenated, improving water quality. Fishing would improve as striper, shad, sturgeon and other species would have better reach of spawning and feeding grounds.

A portion of that run-of-the-river fish passage could also be used as a whitewater course for canoers and kayakers. Commercial whitewater firms have expressed interest in creating such a course at their own expense, giving way to a new attraction and potential for economic opportunities in a struggling part of Augusta.

By now it should be clear, replacing the failing dam is the option that we need to move forward with quickly for the benefit of the taxpayers, our community, the harbor, and the river.

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The writer is science advisor to Savannah Riverkeeper.

 

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