Residents on Wednesday lit into the state Department of Conservation and Recreation over a plan to convert a wading pool off River Street into a spray deck, saying the agency left them out of the loop and calling the plan short-sighted.

DCR officials acknowledged the decision to remake the wading pool at Mattapan’s Ryan Playground as a spray deck had already been made, citing $600,000 in state funding that became available over the summer. Contractors have already been hired and construction is scheduled to start Oct. 15.

The move is part of a larger DCR statewide effort to switch old wading pools to new spray decks, since spray decks require less maintenance. Coneco Engineers & Scientists INC and Traverse Landscape Architects are the contractors for the Ryan Playground project.

No chemical treatment or recirculation system is needed, and the spray decks are set by a timer. The agency says it also does not need to staff spray decks with lifeguards as they do the wading pools.

“In this particular case the judgment was, we could serve far more kids, far more citizens by converting it to a spray deck versus continuing to struggle with the limitations of such a small wading pool,” said Raul Silva, a DCR engineer.

But nearly two dozen people attended a virtual meeting with the DCR officials, with several voicing opposition to the project.

Ruth Georges said DCR’s poor communication about the project is typical of the agency. “It has to stop,” she said. “We’re all taxpayers here.”

She noted that the presentation offered by DCR noted community members would have an opportunity to weigh in on additional changes to Ryan Playground, such as a reconfiguration of the parking lot. That’s offensive, she said.

Ryan Playground, located at 350 River Street and steps away from the Neponset River Trail, also has a playground, restrooms and shaded benches.

“I would like to echo the sentiments of the (other) residents: We would like to know what is the process for stopping this from moving forward,” she said of the spray deck.

Silva, the DCR engineer, said he does not have the authority to say whether the project can be stopped. “We’re going to take this back to senior management,” he said.

Silva described the benefits of a spray deck, arguing that it would double the number of days that the facility is open and increase the number of hours it’s open each day, because the spray deck is automated. There would not be a need for lifeguards, jobs which the agency has struggled to fill.

Overall, a spray deck would doubles the operating season to 18 weeks from the wading pool’s 9 weeks

Silva added that the wading pool is so small that it is chronically at capacity. “And I know it’s a frustration when people show up and there’s a line that heads down the walkway,” he said.

The Ryan wading pool would be the sixth converted by DCR into a spray deck, and the second or third in Boston, according to Silva. Cambridge, Belmont and Fall River have also seen conversions. “This is not an isolated project,” he said.

Fatima Ali-Salaam, chair of the Greater Mattapan Neighborhood Council, said if there were lines at the wading pool that may have been due to another Mattapan pool being closed. She said the agency appears to have a “great disconnect” from the neighborhood, and its decision to remove the wading pool is an example.

“This is not a community engagement process,” she said. “It really isn’t.”

State Rep. Brandy Fluker Oakley added that there is often a feeling of things being “done to” the Mattapan community rather than “with the community. “It feels like we weren’t brought along,” she said, noting that DCR had previously provided her with incorrect information about the wading pool when she recently asked about the project.

City Councillor At-Large Ruthzee Louijeune also noted multiple people want the wading pool to stay.

Silva said the funding becoming available over the summer accelerated the project, in order to get it done by next summer. “We could always do better and I guess what I’d like to say, give us the opportunity to do better in the remaining phase,” he said.

But even before the end of the virtual meeting, which lasted about 90 minutes, Silva acknowledged the opposition to the move.

“I think what we’re hearing loud and clear, we’re going to take it back to our agency,” he said.