Chicago Public Schools officials have said that a pool at a Southwest Side high school was properly staffed when a 14-year-old boy with autism slipped unnoticed by six CPS staffers into a school pool last year and drowned.

But on Wednesday the Chicago Board of Education is set to vote to cut the number of students per lifeguard at CPS pools in half — down from as many as 100 students for each lifeguard to 50.

That’s among steps to beef up water safety planned following the Jan. 25, 2017, drowning of 14-year-old Rosario Gomez in a chaotic pool during a physical education class at Kennedy High School.

There were at least 70 students, part of a double gym class, in the pool when the boy, a non-swimmer, got into the deep end during a unstructured “free day” during which kids could do as they pleased while six adults were on duty, according to a Chicago Sun-Times-Better Government Association investigation last September.

Rosario had significant problems communicating and wasn’t wearing a life jacket, and the school didn’t have an aide in the water with him even though he couldn’t swim, the Sun-Times and BGA found.

CPS officials, who didn’t respond Monday to a request for comment, previously have said that, with six staff members, including a lifeguard, “the pool area at Kennedy was properly staffed based on the number of students in the pool and their specific needs.”

Also according to the proposed new policy the school board is being presented Wednesday to vote on:

• There no longer will be any “non-instructional free swim or open swim activities” like the one that was being held when Rosario drowned.

• School lifeguards will be required to do nothing else during swim class but their lifeguard duties. They would be barred from also teaching or coaching.

• Gym teachers and coaches will be required to get lifeguard certification from the American Red Cross by 2020. But they won’t count toward the reduced ratio of students to lifeguards “unless they engage solely in lifeguard surveillance duties.”

• Water-rescue certification requirements for special education classroom assistants are being spelled out. And those aides will be required to remain within “reaching assist distance” of their assigned students — which isn’t what happened with Rosario.

• PE teachers and aides assigned to special ed students will be required to review each child’s “individualized education plan” to ensure that mandated accommodations for each child — such as wearing a life vest or to have in-pool help — are being met.

When Rosario drowned, none of the six adults present noticed that, minutes after he entered water, he left the shallow end of the pool, which was just three feet deep. Other students spotted the 5-feet-8, 123-pound teenager underwater in the eight-foot-deep end. His assigned gym teacher, who was taking attendance, has been fired. Also fired were a substitute aide and the lifeguard at the pool.

Police reports showed that the lifeguard said it was hard to see the boy “because there were a lot of kids in the pool.” They also said music was “blaring, as it did every day.”

Rosario’s family has sued CPS for negligence, saying he wasn’t properly supervised in larger-than-usual class.