Morgan’s Wonderland, a Northeast Side theme park for special needs children, is embarking on its largest expansion since opening in 2010: a $9.9 million water park.

The 4-acre water park, named Morgan’s Inspiration Island, will include a Ferris wheel, a lighthouse, five splash pads and retail, according to building permits issued by the city. Construction is set to begin in December and finish in March 2017, according to filings from the Texas Department of Licensing and Regulation.

The water park plan was revealed a day after city and county officials unveiled a plan to buy Gordon Hartman’s Toyota Field — which is adjacent to Morgan’s Wonderland — for $18 million and lease it to Spurs Sports & Entertainment, with a goal of bringing Major League Soccer to San Antonio. Hartman, who founded Morgan’s Wonderland, would also receive $3 million from the Spurs as part of the plan.

Park spokesman Bob McCullough said in an email that the park will make a formal announcement next week. Hartman told the San Antonio Express-News this year that he planned to build a wheelchair-accessible splash park between the South Texas Area Regional Soccer Complex and the theme park’s catch-and-release fishing pond.

“For five years, we have grown beyond our wildest dreams,” Hartman says in a YouTube video posted last month that hints at a water park expansion. “But we are just getting started.”

In its first five years of operation, the park has hosted more than 500,000 guests from all 50 states and 50 other countries, Hartman told the Express-News last year.

Morgan’s Wonderland cost about $27 million to build and opened in March 2010. Hartman was inspired to build it after his daughter Morgan, who has cognitive and physical disabilities, was shunned while trying to play with other children in a hotel swimming pool.

Admission to Morgan’s Wonderland is free for special needs children, while other children pay $11 and most adults pay $17.

The theme park is part of a complex of recreation facilities owned by the nonprofit Sports Outdoor and Recreation Park. Revenue has been increasing for the nonprofit in recent years, according to filings with the IRS.

In 2013, the most recent year for which records are available, the nonprofit collected $6.9 million in revenue, up from $2.3 million in 2012. Its operating revenue, which doesn’t include charitable contributions, rose to $3.4 million in 2013 from $864,169 in 2012 and $752,566 in 2011.

The water park is the latest of a string of expansions to local theme parks and resorts in recent years. In July, the JW Marriott San Antonio Hill Country Resort & Spa announced a $16 million project to expand its water park and meeting space. Last year, Six Flags Fiesta Texas built two new water slides, a children’s pool and a swim-up bar.

In 2013, SeaWorld San Antonio opened Aquatica, a water park with three beaches, an aviary, a wave pool and a water slide that takes riders under a stringray habitat. That year, Hyatt Regency Hill Country Resort and Spa finished a $35 million expansion, adding a wave machine and a tower slide to its water park, among other things.

The Morgan’s Wonderland addition will be designed by Luna Architecture + Design, a local firm that worked on Toyota Field and several local hotels, including the Wyndham Garden hotel. It also worked on Morgan’s Wonderland earlier, according to its website.

rwebner@express-news.net

Twitter: @rwebner

Express-News archives contributed to this report.