The fate of the proposed sales-tax increase to pay for Reid Park Zoo upgrades was in limbo Tuesday night after Tucson voters were split on the two propositions that need to pass for approval.

Proposition 202 would amended the city charter to enable the change for the sales-tax increase. It was slightly ahead with 52 percent of the vote. And Proposition 203, which would approve the tax hike for capital improvements, was split evenly.

The tax fails unless both propositions pass.

More ballots were to be counted Wednesday, but it wasn’t clear Tuesday night how quickly the outcome of the vote would be known.

At an election party for supporters at the zoo Tuesday night, Nancy Kluge, president of Reid Park Zoological Society, remained optimistic.

Kluge said she was celebrating that Proposition 202 was leading. And Kluge said she would wait for more results to come in for Proposition 203, adding she was looking forward “to start building new, exciting features for the zoo.”

The propositions, or the Future of Your Zoo initiative, would raise between $8 million and $10 million annually, by increasing the city’s sales tax.

A recent poll showed the one-tenth-of-a-cent increase in the sales tax to benefit the zoo was supported in the city by 55 percent of those polled. It was opposed by 33 percent of the respondents.

The zoo just celebrated its 50th anniversary, and officials said they are proud to have witnessed its growth.

However, they also said the aging facilities are creating some financial strain.

Underground sewer, broken water pipes and guardrails need replacing. Some animal habitats are up to 50 years old and need to be replaced to meet current zoo standards, Kluge said in an earlier interview.

The society has been successful over the years in raising funds for new exhibits, but the infrastructure needs are beyond the scope of fundraising, Kluge has said.

The zoo attracts 500,000 visitors a year, said Kluge.

Critics say a sales-tax increase is the wrong way to finance such improvements, especially since not everyone who would pay the tax supports the concept of zoos or visits them.

In an earlier interview, critic Robert Reus said he believes the people who support the zoo should donate the funds for it.

Contact reporter Carmen Duarte at cduarte@tucson.com or 573-4104. On Twitter: @cduartestar