When Earl and Pat McConnell moved to Paradise Point almost 20 years ago, the nearby swamp provided a tranquil backdrop to the Slidell-area subdivision. Since Hurricane Katrina, however, it has started to look more like a threat, swallowing up a good 75 feet of land at the rear of their property and that of their neighbors.

“See this?” Earl McConnell said, pointing to a strip of mowed lawn between his next-door neighbor’s back fence and the water. “This is just swamp waiting to happen.”

The opposite is happening in River Oaks, another upscale neighborhood along the West Pearl River and its tributaries.

Boathouses like Jerry Whitman’s stand empty, the water so shallow that homeowners can no longer launch vessels from their docks. Whitman’s pontoon boat sits in his driveway instead.

For one neighborhood, the problem is too much water; for the other, not enough. But in both cases, parish officials and residents blame the same culprit: heavy silting and debris that have clogged the waterways since hurricanes Katrina in 2005 and Isaac in 2012.

Clearing out the sediment and debris is not a simple matter, in part because the West Pearl River is covered by the Louisiana Scenic Rivers Act, which restricts activities such as channelization, clearing and removing snags.

Parish Councilmen Gene Bellisario and Richard Artigue said they have been working for a couple of years to get some relief. After Katrina, some debris was removed from the river, Bellisario said. But those efforts were closely scrutinized by FEMA and the U.S. Army Corps of Engineers, which had personnel on hand during the work to dictate what could and could not be removed, Bellisario said.

In some cases, debris was left in place because officials didn’t believe its presence was storm-related, he said. And the effort did not include removing silt, Bellisario added, even in areas where banks were sheared off during the storm and dumped into the river. As a result, he said, the work provided only limited relief.

McConnell said the heavy silting and debris are causing a bowl effect in the swamp and interfering with the free exchange of water. Now, when heavy rain falls on the river, the swamp fills up and inundates his yard and others.

He and his neighbors worry that the phenomenon will leave them more prone to flooding.

During Hurricane Isaac, they say, the water was much higher than residents expected from a Category 1 storm.

Elizabeth Dewenter, president of the River Oaks homeowners association, said the situation is going to make homes difficult to sell. She pointed to one that has been on the market for two years.

Bellisario calls the situation an unintended consequence of the state’s Scenic Rivers Act, which was adopted in 1988 to protect rivers like the West Pearl.

Mark Schexnayder, deputy assistant secretary of the state Department of Wildlife and Fisheries, said the act provides another layer of protection but does not prohibit dredging, pointing out that his agency has approved dredging projects on parts of the lower river system in the past decade.

The Army Corps of Engineers has done dredging in the area before, but the last time it tried to resume dredging for commercial traffic on the river, a lawsuit was filed on environmental grounds and the agency was ordered not to go ahead.

Beyond the issue of authorization, there’s the question of appropriation, said Greg Raimondo, a spokesman for the Corps.

“That’s such a low, flat river and slow-moving,” he said. “It’s going to silt in every year.”

In the meantime, St. Tammany Parish has paid $400,000 for a model of the river system that is being created by the Naval Research Lab at the nearby Stennis Space Center. The model will provide a broader understanding of the river and insight into flood risks and where obstructions are a problem. Schexnayder said.

The model will be used by the Lower Pearl River Ecosystem Study Commission to create a master plan for the basin, St. Tammany Parish spokeswoman Amy Bouton said.

Those who believe dredging is the answer to problems on the West Pearl expect that opposition might surface from conservationists who fear potential ill effects on habitat.

But McConnell thinks there’s a way to remove the silt that is slowing the river’s flow without harming the species that live there. “We’re smart enough to do that, aren’t we?” he said. “We can cooperate and address their concerns and ours, too.’’

Follow Sara Pagones on Twitter, @spagonesadvocat.