DAILY PILOT HIGH SCHOOL ATHLETE OF THE WEEK:

She’s not growing gills or anything drastic like that, but Katie Jackson just loves being in the water.

The Newport Harbor High sophomore wouldn’t have it any other way. Sometimes on weekends when she’s bored, she said she calls up some friends and heads over to the Harbor pool for some shooting, lap swimming or just to play in the water.

“I’m probably one of the few, if not the only, water polo player that loves swimming,” Jackson said. “[Teammates] are like, ‘Ugh, swim season,’ and I’m like, ‘Yay! Swim season!’

That’s why this week has been so tough for the Daily Pilot Athlete of the Week. Jackson sat out Tuesday’s Sunset League meet against Esperanza with a sore throat. Then, on Wednesday, she went to her pediatrician and Jackson was diagnosed with mononucleosis.

“We did a blood test for it,” Jackson said. “Hopefully, I heal fast so I can get back in the pool as soon as possible.”

The mono means Jackson hasn’t been going to school. She’s just been getting plenty of sleep, which is perhaps the best treatment. But even when she starts feeling better, athletes are advised to take it slow. Those infected with mono often have an enlarged spleen, which could rupture and require immediate surgery.

“I wish they could just drug me and make me feel better,” Jackson said. “It’s extremely frustrating, because I do care so much about swimming. When I first found out I had mono, I just came home and cried and got so frustrated. I didn’t want [Coach] Ken [LaMont] to be upset, because I am one of the only girls who really does care and tries extremely hard. I didn’t want to have to let him down. But hopefully, I’ll recover fast, so I can get back in and go back to CIF this year. That would be really cool.”

LaMont certainly thinks so, too. Jackson is one of his most valuable swimmers, and she showed her swimming prowess again on March 11, in the season-opening dual meet against Back Bay rival Corona del Mar.

Jackson won a pair of events for the Sailors, the 200-yard freestyle (2 minutes, 2.05 seconds) and the 100 butterfly (a CIF Southern Section Division I consideration time of 1:02.45). The individual victories, along with Jackson’s part in both of Newport Harbor’s winning freestyle relays, helped the Sailors girls come back and tie the Sea Kings, 85-85.

“She’s a very talented swimmer in a couple of ways,” LaMont said. “She’s good at what she swims, and very versatile in what she swims. I can match her up, depending on who we’re swimming against. She has a lot of events in her arsenal.”

LaMont said Jackson can also swim the 200 individual medley, the 500 free or some sprint events for Newport Harbor.

“You’re always happy to have someone like that come into your program,” he said. “You’re always excited knowing you have four years with that athlete.”

She started out strong her freshman year. Jackson finished fifth at the Sunset League finals in the 200 free, and qualified for the Division I finals in the 100 fly.

Jackson finished 27th in the Division I preliminaries in the 100 fly, in 1:02.46. She and Kate Klippert, then also a freshman, were the only two Sailors girls to advance to Belmont Plaza in an individual event.

“At first, I was kind of disappointed, because I was ranked so low in it,” Jackson said. “I was like, ‘Oh, there’s no point in me going if I’m ranked so low.’ I was one of the last people on the list. But, it was actually a really cool experience, because I went with Kate ... It was just cool that nobody else made it except for two freshmen.

“We had something on everybody else, so we could just brag about it,” she added with a laugh.

Jackson may not always brag about her swimming, but she said she’s really competitive and she hates to lose. That makes sense, considering how much time she’s put into the sport. Even her favorite movie — “Finding Nemo” — takes place underwater.

“I’ve been swimming my entire life,” said Jackson, whose older brother, James, swam and played water polo for Newport Harbor before graduating in 2006. “I started out at Newport Shores, then I did this club called Splash. I was really excited when I came into high school because I had heard our coach was Ken LaMont, who’s one of the [Irvine Novaqatics] coaches. I just like it so much and hope I can do it until I’m really old and wrinkly.”

Katie Jackson also plays water polo. A utility player, she spent this past season on the Newport Harbor junior varsity but was one of two postseason call-ups to the varsity. Even if she didn’t get in much during the playoffs, she still appreciated being a part of the Sailors’ Division I championship team.

“It was so cool,” Jackson said. “It was amazing that we won. It just makes me want to win next year and the year after. Being on the bench was nice, because I had a front-row seat. I didn’t have to sit in the crowd with all the screaming, annoying parents. I was just really proud that I had that opportunity.”

But soon after the water polo victory, Jackson said she started feeling sick. She said that made her pleasantly surprised at her winning times against CdM.

Even if she’s currently battling mono, however, don’t count the determined Jackson out. After all, she just loves to swim.

“I think she has that element where she just has a pretty good feel for the water,” LaMont said. “You can’t really teach that.”

MATT SZABO may be reached at (714) 966-4614 or by e-mail at matthew.szabo@latimes.com.