Troy Schexnaydre slowly weaved his fishing boat past interwoven tree branches hanging low over the water and worked around tree trunks poking up at odd angles.

Schexnaydre and his passengers listened for the occasional thud from the bottom of the 20-footer that announced the presence of a submerged log, sometimes tipping the boat uncomfortably to one side.

This wasn’t some remote tropical river, but Ascension Parish’s Panama Canal, a waterway vital to the parish’s rainwater management. And that overgrown vegetation isn’t just a mild nuisance for boaters but a hindrance to adequate drainage during severe rainstorms like the deluge more than a month ago that flooded Astroland and other areas south of Interstate 10.

Eighteen inches of rain fell in the Bayou Conway-Panama Canal watershed between May 28 and June 2, flooding streets in Pelican Point, dozens of houses in Astroland and 109 homes across the parish. According to East Ascension drainage officials, the first day of the downpour was a 500-year event for a 24-hour period. In the Panama Canal area, the storm dropped 12.9 inches in 17 hours.

The storm rivaled Tropical Storm Allison in June 2001, considered the modern-day standard for a heavy rain in Ascension, officials said.

The parish has spent hundreds of millions of dollars on drainage improvements since East Ascension voters approved a half-cent sales tax in the mid-1980s, building the Marvin J. Braud Pumping Station, clearing out bayous and canals and installing a flood gate in the north end of the parish. But Ascension has grown rapidly during that time, too, and parts of the parish, which has swaths of low-lying territory where people continue to build new homes, remain susceptible to flooding.

With so many houses flooded by the rains in late May, frustrated community members have quickly moved from early criticism of the performance of first responders to questioning what is being done to solve the larger drainage woes in Ascension Parish.

During a recent public meeting in Astroland, Galvez resident Leroy Brown brushed aside attempts to rehash law enforcement’s failure to evacuate a comatose man from a flooded house. Although the man was his nephew, Brown said he’s worried about the bigger picture.

“We just have a water situation that we need to deal with back here,” he said. “We need to move on to the water situation.”

Problem, fix complicated

The untamed growth of trees and plants across the canals isn’t the only problem. Highway and railroad crossings that cut across the waterways southeast of Sorrento also constrict water flow, while the entire lower end of the system is susceptible to wind and tidal forces from Lakes Maurepas and Pontchartrain.

Parish officials are faced with devising a complex array of fixes, which not only must be approved by the U.S. Army Corps of Engineers but also require substantial parish investment. Officials, though, believe they have come up with workable solutions, touting still-developing plans to improve drainage in the Conway-Panama watershed — as well as separate plans to fix west bank problems. The exact price tag and timeline for these projects are unknown.

Along with taking care of the vegetation, officials want to open the man-made restrictions in the bayous and reroute water to the Marvin J. Braud Pumping Station in McElroy Swamp, where a new $4 million pump would be built. Looking ahead even further, parish officials envision creating a large regional pond along the Panama Canal to hold flood water temporarily or possibly building another set of pumps to send flood water into the Mississippi River.

Parish President Tommy Martinez says while some of the immediate fixes now being discussed need to be moved on quickly, he also would like to hire an engineering firm to study longer-term improvements.

“We need a big picture plan,” he said.

For western Ascension, officials are talking about seeking emergency Corps permits to dig out a sandbar in Bayou Napoleon just over the St. James Parish line. The sandbar is six inches from the bayou’s surface and, along with fallen trees and natural growth upstream of the blockage, causes storm runoff to back up in Donaldsonville, surveyors have reported.

The area encompassed by the Conway-Panama watershed tracks the Mississippi River, sweeping up cane fields and pastures, along with the 800-acre Pelican Point golf course development and the nearby Ascension Trace and Pelican Crossing subdivisions. It also includes the Astroland neighborhood and historic Darrow community farther west.

The Conway is a natural bayou where Sorrento’s first settler, Desiré LeBlanc Sr., established a home in the 1860s. The Panama is a former agricultural ditch first built by farmers. Both snake across the area and drain into the upper reaches of Blind River swamp in Ascension and St. James parishes.

Flooding in the watershed is not relieved by the Marvin J. Braud station’s six pumps, which handle rain that falls in Gonzales, St. Amant and part of Prairieville, nor by a smaller pumping station in Sorrento. The Conway-Panama watershed’s drainage relies on gravity alone.

East Ascension Drainage Director Bill Roux and Parish Councilman Kent Schexnaydre, who provided a tour of the problems during Troy Schexnaydre’s recent boat trip, said he lower Conway and Panama bottleneck in the Blind River area. The problem is the maze of undersized or silted-in road and railroad crossings that impede water flow.

During the boat trip, a Kansas City Southern freight train roared across a railroad bridge, speeding seemingly just above the surface of Bayou Conway inside the Maurepas Swamp Wildlife Management Area.

Councilman Schexnaydre shouted over the driving din of passing chemical tankers: “Everything in that whole system comes through this.”

He pointed to the rail bridge, held up by narrowly spaced pilings that block the water.

Roux says parish officials are looking at widening the openings for water under the KCS bridge and under Airline Highway to the east so Bayou Conway can flow more easily. Another idea is restoring an overgrown route of the old Panama Canal that was abandoned after the interstate was built.

C. Doniele Carlson, spokeswoman for KCS, said the railroad was not aware of the parish’s plans but is open to cooperating. She added the railroad would need to give a more thorough review to any projects affecting the Bayou Conway bridge.

Fixes, permitting intertwined

Even before the May floods, parish officials knew the foliage growth in Bayou Conway and Panama Canal was a major problem. In fact, East Ascension drainage officials are in the middle of spending $1.8 million with a company that specializes in clearing out waterways and bayous.

It was a long time coming. Parish officials estimate the 29 miles of the lower Conway and Panama hadn’t been cleaned out in 25 years, a failure they ascribed to decades of focusing on priorities such as major infrastructure construction. Another factor until recently was a lack of funding for bigger projects.

Chem Spray South Inc., the company hired to clear out the bayous, was already a few months into its work when the heavy rains started in late May.

“What we’re doing is we’re taking anything out that will affect the water flow,” said Todd Johnson, a Chem Spray sales executive.

The remaining work is expected to take two months. Chem Spray employees in boats are sawing and hacking through the tree branches, although some work can be done by heavy equipment brought in by barge or that is designed to move in the swamp.

It won’t eliminate all of the vegetation. More extensive removals, such as digging out banks to remove waterside trees, would require complicated Corps of Engineers permits, which East Ascension officials specifically designed the project to avoid.

John Herman, chief of the Corps Regulatory Branch’s Central Evaluation Section, said other federal agencies that review permits want to see the tree canopy preserved over the waterways to protect the health of fish and other aquatic habitat. The design of the clearing project means, even with much of the vegetation pruned back, the canal and bayou can only handle so much water.

For that reason, Roux and other parish officials are proposing to widen natural and man-made connections between the Marvin Braud and Conway-Panama watersheds and to install gates that would allow officials to route water from one area to the other.

Overflow from the Conway-Panama watershed would end up in Bayou Francois in the Marvin Braud pumping system watershed. That water would be pumped out with the envisioned seventh pump to swamps in the lower Blind River basin to avoid the blockages where water flows under Airline Highway and the KCS railroad line.

However, those plans raise other concerns. For many years, leaders in St. James Parish claimed the Marvin Braud pumps push water into their parish. Ascension officials have disputed that, arguing numerous engineering studies show the effect is minimal.

St. James Parish President Timmy Roussel said talk of a seventh pump concerns him and may drive his parish to start looking at a tax millage to build ring levees around populated areas and other flood-control measures.

He said 80 percent of the parish’s east bank drainage goes through the Blind River. He acknowledges engineers have claimed the sixth Marvin Braud pump, which was finished about a year ago, likely would cause a only a half-inch rise in St. James, but said even that amount is too much.

“Would you want no water in your house or a half-inch in your house?” Roussel asked.

Ricky Boyett, spokesman for the Corps’ New Orleans Branch, said Ascension’s overall plan doesn’t raise any immediate red flags, but officials would have to see more details before signing off on it.

Martin Mayer, chief of the Corps’ New Orleans District Regulatory Branch, said that as Ascension, East Baton Rouge and other parishes continue to dig out canals and build pumps and levees for their expanding populations, more water is shunted quickly downstream.

“You’re essentially moving water and putting it on someone else and letting it be their problem,” he said. “That happens a lot.”

Follow David J. Mitchell on Twitter at @NewsieDave.