Pools Bluff Sill Dam: Why is it still in place today?

Jul 26, 2018

With the discussion and public hearings for the proposed One Lake Project being held over the next few weeks, the possible impact that project could have on the East Pearl River is front and center on residents in south Mississippi and Louisiana.

To understand how the diversion of water on the East Pearl River has continued to create more and more problems, let’s take a quick look back on the why and when the sill dam was put in place at Pools Bluff.

Low Water Sills and Low Head Dams are underwater concrete barriers placed along the width of a river to regulate flow, usually resulting in a change in the height of the water level. These sill dams are often difficult to detect from up-river and may not appear to be dangerous to boaters or swimmers. The hydraulic forces and recirculating currents are in fact extremely hazardous and can swamp boats and drown swimmers. CBS News reported: "Since the 1950s, at least 441 people have died at 235 low-head dams in 38 states, according to researchers at Brigham Young University".

In 1935, the U.S. Army Corps of Engineers’ (USACE) "Pearl River Navigational Channel" project dredged a 20 mile canal with 3 locks from south of Bogalusa to the mouth of the West Pearl River.

In the 1950s the USACE built 3 low head sills (the one at Pools Bluff south of Bogalusa, one at the Bogue Chitto River and one at the spillway) to help maintain water levels in the Navigation Canal.

Excerpt below is from 1941 Chief of Engineers Annual Report

The USACE placed the project in "caretaker" status in the 1970s, because of a decline in commercial traffic. Maintenance dredging resumed in December 1988.

The sill at Pools Bluff today causes a major problem in low water conditions on the East Pearl River; it prohibits boaters going north. As stated above, the whole purpose of the sill dam was to divert more water from the East Pearl River to the Navigational Canal.

Today, the Navigational Canal is a recreational waterway for boating, water skiing, fishing, and swimming. What was once put in place mainly for the logging business, does not appear to serve any valuable purpose for today’s use of both the Navigational Canal and East Pearl River.

In its 2011 Comprehensive Conservation Plan for Bogue Chitto National Wildlife Refuge area of St. Tammany and Washington Parishes, Louisiana, and Pearl River County, Mississippi, the U.S. Department of the Interior Fish and Wildlife Service Southeast Region office states its desire and opinion on the sills.

“The Service wants to see the river remain as natural as possible; therefore, it has no plans to dredge any portion. Dredging of the Pearl River Lock and Dam System or the Pearl River from Walkiah Bluff south to Wilson Slough may be performed by the USACE as

state waters. The Service supports removal of all sills along the river, but has no authority to do so.”

There was a time that a boater heading in either direction on the river at Pool’s Bluff could leave the water, load its boat on a rail trolley, and unload the boat on the other side of the sill. Today that rail trolley is not in service , thus there is no way to proceed up or down stream during low water conditions. The sill dam at Pools Bluff has also prevented gulf sturgeon and other migratory species from accessing upstream according to the same report from the U.S. Department of Interior report referenced earlier.

Longtime river navigator Jeremy Magri stated, “It’s time for the sill dam at Pools Bluff to be removed. It does not serve any commercial purpose anymore plus it is still diverting the flow of the river to the west.”

Video of Pools Bluff Sill Dam