Plans for a new Trinity River park just outside downtown Dallas got a boost Monday with the announcement of a $50 million donation from a private donor.

Annette Simmons, the widow of late banking billionaire Harold Simmons, gifted what is believed to be the largest donation to a public/private partnership in Dallas.

The $50 million donation, along with $30 million in city funds, is expected to launch the first construction phase, five months after Mayor Mike Rawlings unveiled designs for the project.

Plans for the 155-acre development include multiple elevated parks, walking trails and a river landscape, and, according to renderings of the proposed finished project, more water.

"I believe we can create the most value and the greatest benefit to our citizens when we complete projects around nature," Rawlings said Monday of what would be named Harold Simmons Park.

Rendering shows Trinity River park plans. Photo: Trinity Trust

"This is a transformational moment in the life of this project and this city,” Rawlings said. The Trinity Trust dubs it as “one of America’s greatest urban parks.”

Simmons’ donation is contingent upon the park being privately managed and the remainder of funding being secured in the next three years.

“This gift will begin the creation of a great public space in our city that will be a place to gather, to enjoy nature and promote health and well-being,” Simmons said in a press release. “I cannot think of a more lasting and meaningful way to honor Harold’s memory and legacy.”

Rawlings said Harold Simmons "dedicated his life to giving his money to a long list of noble causes."

The park would not affect the polarizing plans for the proposed Trinity Parkway.

Here's what the Trinity River Park could look like