Davis Pond Freshwater Diversion Project
Friday, December 19, 2003
CC's Journal 6

Out flow channel at Davis Pond freshwater diversion project
into Lake Cataouatche at a flow of 2,500cfs .

What does the Louisiana coast need for Christmas? Fresh water to dilute salt water and sediment to restore lost land, and Davis Pond is a great place at which to start.

Sliding atop a bayou like water droplets trying to escape the surface of a hot griddle is what it felt like to travel by airboat down Bayou Verret. Biologist John Troutman was at the throttle of the 454-cubic inch V-8 engine that enables these unique boats to quickly reach the far corners of the marsh. Engineer Tom Bernard and biologists Chuck Villarrubia and Jon Barmore shadowed us in a second airboat. All four of them, with the Louisiana Dept. of Natural Resources, were on the outing to fill us in on the Davis Pond freshwater diversion project and the wetlands it affects.

We stopped near the northwestern shore of Lake Cataouatche (7 miles southeast of Luling, in St. Charles Parish) to examine the rock gabion (rocks in a wire bag) weir that borders the southeastern portion of Davis Pond. Northwest of that levee is the 9,300-acre project ponding area of mainly flotant marsh and a few finger ridges that support bald cypress trees. Fresh water from the nearby diversion structure on the Mississippi River's west bank flows into this ponding area before exiting at four outlets into the 770,000-acre Barataria estuary toward the Gulf of Mexico. This fresh water can reduce the salinity of the entire 770,000-acre estuary.

The long contemplated Davis Pond and close by Caernarvon freshwater diversions were eventually authorized by Congress back in 1965. I found this surprising, as political concern about Louisiana's vanishing coast has only recently been widely publicized. The Caernarvon project was completed in 1991. Despite its being called a "freshwater diversion" public work, it has added 150,000 tons of sediment to the wetlands southeast of New Orleans. The Davis Pond project was completed in March, 2002.

Chuck told us presently 2,500 cubic feet of water per second flows out of the Davis Pond water control structure on the Mississippi and into the ponding area. He said when it is allowed to discharge at full capacity (4¼ times the current rate), water runs over the ponding area's rock gabion levee into Lake Cataouatche. I saw at an outflow channel outlet very turbulent rapids. Looking at that raging discharge, I had a hankering to go get my kayak and do whitewater playing!

We entered the pond to see some measuring devices that John monitored. At each location he had one gauge to check on the overall water level, and another was in the flotant to measure its vertical movement relative to the overall water level. Generally, the thick stemmed Sagittaria-dominated marsh tends to sink, while that of the lighter, thinner grasses is more buoyant. The water was surprisingly clear, and we could see the organic material on the water's shallow bottom. We stopped at one flotant mass that was literally covered with a pod of preening nutria, and we walked on it (I did not sink; my diet was working). It was indeed "trembling earth," for it wiggled as if we were walking on the surface of a big bowl of Jell-O.
A few finger ridges with bald cypress attractively decorated the western side of the pond; the tree leaves were a bright rusty red. Who says Louisiana does not have fall colors? They have been great this year!

According to Chuck, the Davis Pond project not only continuously revitalizes 1,214 sq. miles of salt-threatened wetlands but also annually benefits fishing to the tune of 15 million dollars and saves 51.5 sq. miles of marsh! Obviously the birds like their new environment, for we saw many avian species. Thousands of American Coots flushed ahead of us, and egrets, herons, ibis, shorebirds, vultures, gulls, and hawks flew nearby. Best of all was seeing a pair of airborne bald eagles lock talons and tumble out of the sky in their mating ritual; it was the second time I have seen that this year. I had another bald eagle treat a few days ago on the south shore of Lake Pontchartrain, when one flew off of the shore in front of me with a laughing gull firmly grasped in its talons.

It took over three decades to get these two projects governmentally approved and built. It will take many more like them to completely save and restore Louisiana's wetlands. Each new one will be very complicated and require interest groups from all walks of life to persuade their state and national government representatives to support it as a statewide and national priority. The big picture to me is that to effectively and expediently restore the wetlands, we have got to come together and do this as a unified group.

Find out more interesting facts about the Davis Pond project at: http://www.mvn.usace.army.mil/pao/dpond/davispond.htm or