BOUTTE — Scientists will be trying out a new way of operating the Davis Pond Freshwater Diversion project later this year to get more water through the system when the Mississippi River levels are high.
First authorized by Congress in the 1960s and then opened in 2002, the diversion has been operated based on a monthly average of how much salt water is in the Barataria Basin. Previously, a task force of user groups, state and federal officials have formed an operating plan that dictates how much fresh water from the Mississippi River should be let through the structure to keep a 5 parts per thousand salinity level.
Now, explained Chuck Villarrubia, senior scientist with the state Coastal Protection and Restoration Authority, the task force is going to base operations on a 15 parts per thousand level from December to May. That’s when there is typically high water in the Mississippi River and historically a time of year when the river might flood over its banks into these wetlands, he explained during a Tuesday trip to the diversion site.
The rest of the year, the operation will manage for the 5 parts per thousand line, which is typically when water in the Mississippi River would be lower and maintained within its banks.
This type of operation better mimics how nature operated before the levees were put up along the Mississippi River.
“The new plan will give us a greater ability to use the river when it’s on,” Villarrubia said.
Denise Reed, chief scientist with The Water Institute of the Gulf, said it reflects a change in attitude when it comes to environmental projects.
Reed said the 20th century was all about controlling nature, so controlling salinity was the goal set for the Davis Pond Freshwater Diversion project. However, in the 21st century it’s about working with nature, she said.
“None of the river diversions being planned now are talking about controlling salinity,” Reed said.
These salinity levels used as guides for “controlling” saltwater intrusion were on the map based on how we were thinking in the 1960s, she said.
Although the diversion has been in operation since 2002, there have been limits on how much fresh water is allowed to flow through the structure.
“Over 10 years now that we’ve had this structure and we’ve still not been able to fully utilize its capabilities,” said Ted Falgout, vice president of Restore or Retreat coastal group.
Villarrubia said there were initially problems with putting too much water into the system because of drainage problems. Eventually, guide levees on the sides of the 9,300-acre receiving area were stabilized and cuts were made into the lower area to allow water to better drain into the lakes, he said. That work was completed in about 2008.
Another problem, Villarrubia said, is the whole operation is based on salinity control and that has been a constraint on how the diversion is operated and how much water was allowed to flow through the structure.
The Water Resources Development Act of 2007, however, gave the corps and state authority to look at modifying the way the diversion is operated to maximize benefits.
The project officially “started” in 2009 when the state and corps signed a cost-share agreement, and the corps stated in a fact sheet earlier this year that the planning team was close to selecting a recommended plan with a completion date of November 2013. However, the state requested in October that the feasibility study for the project be suspended.
Bren Haase, deputy chief for planning and research division with the state Coastal Protection and Restoration Authority, explained that the time and money it would take to get the plan through the process may not give any better results than just modifying what they’re already doing.
“We can probably accomplish our goals without going through the effort and expense,” he said.