When plans by the Archdiocese of New Orleans to build a church, cemetery and retirement complex north of Mandeville ran into protracted neighborhood opposition in 2013, St. Tammany Parish officials pointed out the area’s main throughway would be widened, addressing some of the neighborhood’s concerns.

The parish accepted a $1.6 million bid for widening 1.57 miles of Dove Park Road, a project that it originally had budgeted at $2.25 million.

But now that project is stirring controversy of its own. Terri Lewis Stevens, one of the most outspoken and persistent critics of the archdiocese’s plans, believes that drainage work being done in conjunction with the road widening will cause flooding on her property and that of her immediate neighbors.

Roadside ditches that now carry runoff from neighbors to the south of the roadway will be eliminated in the work, and Stevens fears that adding culverts will direct more water to her property, where there is an existing drainage swale.

That swale, in effect a small creek, is intended to carry runoff from her property and her neighbors, she says, and not from the rest of the neighborhood and the new development.

Stevens’ next-door neighbor, Jennifer Rivera, shares those worries. She says her 5-acre parcel already has drainage problems, and water that fills the swale has eroded the back of her property.

Stevens wants the parish to fix the problem by redirecting the flow elsewhere. Otherwise, she says, the parish should buy her out.

But the parish has no plans to do so. Ronnie Simpson, a spokesman for Parish President Pat Brister, said the road-widening was being done at the request of the neighborhood.

When Stevens brought up her concerns, the parish responded by having an engineering firm, J. Thibodeaux and Associates, evaluate the plans. That review, dated Jan. 5, concluded that the work won’t cause the woes that Stevens anticipates, Simpson said.

Storm water is already flowing to the north, but now it goes both under the road, through existing culverts and over the roadway.

“It’s a safety issue as well as an engineering issue,’’ he said. The drainage going across the road shortens the life of the asphalt and makes it unsafe, he said.

Changing the drainage in the area would cost significantly more, Simpson said, and taxpayers would bear the cost. “I think if you’re going to base an action that’s going to require taxpayer money, you want to base it off of science, not on a gut feeling,’’ he said.

Stevens said that if the only alternative or the best alternative for the neighborhood were to direct the runoff toward her land, she would be willing to support the parish’s plans. But she thinks her property will be devalued.

She said her initial plan when she bought the 5 acres was to resubdivide it into three lots. That no longer seems like an option, because the swale, which runs along the back of Rivera’s property, cuts across hers.

She described learning about the parish’s plans as a shock and said her only recourse would be to sue the parish — at her expense.

“Instead of doing the right thing, they are taking the more difficult path,’’ she said.

Rivera said she tried to get information from the parish about the project but received no answers to four emails.

She wrote that she and her husband were concerned about the discharge of storm water onto their property and the possibility of polluted water collecting there.

Stevens and Rivera both pointed out that homes in the area are on septic tanks and that they can tell when someone’s system isn’t working well because of the smell.

Simpson said responding to residents is a priority of Brister’s administration and that he would follow up on why Rivera did not receive a reply to her emails.

Follow Sara Pagones on Twitter, @spagonesadvocat.