Barton Springs pool, the 3-acre, spring-fed swimming pool in Zilker Park is an Austin crown jewel and is visited by hundreds of thousands of people each year.

If trends continue, Barton Springs will see over one million visitors in 2019, which has caused concern from city parks officials who say such attendance levels could substantially impact the pool’s water quality, operations and staffing.

Large attendee increases happened over the past two years, aquatics division manager Jodi Jay told parks board members on Tuesday night. Between 2016 and 2017, Jay estimated attendance increased from roughly 500,000 visitors to 750,000. She said roughly 975,000 people visited the pool in 2018.

“It’s something that, if trends continue, we think we should monitor and come up with a plan on how to best protect the facility,” Jay said.

She said such attendance levels could drum up staffing challenges and negatively impact the overall comfort of the facility and the cleanliness of the pool’s spring water.

Board member Rich DePalma emphasized the need to begin preparing so the city can avoid a Hamilton Pool situation. In 2016, Travis County surprised many by requiring reservations to enter Hamilton Pool—a natural swimming pool attraction located 23 miles west of Austin—in an effort to reduce congestion and preserve the site.

“We need to get ahead of this so we have a plan,” DePalma said.

Jay said there is no predetermined attendance threshold that would spark action from the city, and the parks department would likely need one more summer of attendance before they decide on a path forward.

New increases in entrance fees to the pool could slow the attendance trends, Jay said. The new fees, instituted in October at the start of fiscal year 2018-19, increased fees for resident adults from $3 to $5 and raised fees for all other age groups by $1. These the first entrance fee increases since the 1990s, said Shelley Parks, spokesperson for the city’s parks department.

Barton Springs pool is often cited as the most Austin-y attraction in the city. Actor Robert Redford claims to have learned to swim there, and Mayor Steve Adler often shares the anecdote that he fell in love with the city when he ended up in the pool 15 minutes after he moved to Austin in the 1970s. The pool has also been used as a backdrop in several movies.