"It's pretty tough competition in those senior groups, so winning this puts her right up there. She's one of New Zealand's top junior sprinters."
Also successful in the event at Hamilton's Porritt Stadium were Harvey Meyer who placed fourth in high jump and Olivia Pickford who picked up bronze in the discus.
Williams also earned a silver medal for the mixed relay with Meyer and Lucas Martin, while Brian Wilson competed in track events as well as shot put and discus.
Williams moved to the River City last year, joining Wanganui Collegiate School and officially becoming a Whanganui runner.
She made the move at a good time for junior athletes in Whanganui as the club rebuilds.
"We've had athletes go to the Colgate in the past, but the junior club was in decline a few years back and we're just building it back up," Brunger said.
"The club has grown hugely over the last few years. We've got about 150 kids now and we had been down to 10 or 12. It's been really neat to see those numbers grow."
Athletics Wanganui Inc has two sessions on-the-go for juniors. One is a fun run, jump and throw early on Monday and the other more of a coaching session later that night.
They successfully reintroduced the fastest kid on the block competition a few years ago in which kids race in heats at local parks representing their neighbourhood.
The finals of those heats will be raced at the Cooks Classic at Cooks Gardens on Tuesday, January 15.