The RV park at Napa Valley Exposition in Napa, Calif., is supposed to be a big moneymaker, helping the fairgrounds survive the loss of state financial support.

But fair directors learned last week that the 35-space campground may also represent a financial liability, with the Expo potentially owing $141,500 in sewer hookup fees to Napa Sanitation District, the Napa Valley Register reported.

According to the district, the Expo never paid hookup fees on 16 older RV sites built after 1974 but long before nine new ones came online last year. The district wants $50,940 paid within 60 days on the new hookups and $90,560 paid in installments over the next five years on the older ones.

Fair director Eric Lehman said the Expo is ill prepared to handle this “$141,000 surprise” without potentially raising fees for building rentals, RV camping and possibly tickets for the Napa Town and Country Fair, the Expo’s biggest source of revenue.

“It doesn’t just come out of magic somewhere,” Lehman said of Napa Sanitation District’s proposed hookup fees.

Joe Anderson, the Expo’s CEO, said the fairgrounds doesn’t have the financial cushion to handle such a big bill. The Expo lost state subsidies valued at $280,000 per year in 2011. This reduction in state funding prompted the Expo to raise fair ticket prices last year.

Anderson told directors last week that he had been expecting to pay connection fees for the nine new RV sites, but wasn’t prepared to be dinged for the older connections.

“There are several different things wrong with this,” Anderson said of Napa Sanitation District’s proposed payment.

According to Anderson, the Expo has decommissioned a handful of fairtime kitchens in recent decades, thus reducing its sewage load at the August fair. The district should give the Expo credit for this, he said.

“All this is extortion, is all it is,” Mark Gasster, fair director, said of the Napa Sanitation bill.

Directors suggested that Anderson and board president Al Wagner work with Napa Mayor Jill Techel and county Supervisor Mark Luce, who sit on the sanitation district’s board of directors, on a political solution.

Tim Healy, Napa Sanitation’s general manager, said Monday that he wanted to hear the Expo’s case for fee reduction. “We’re certainly willing to talk to the Expo about what they’ve done out there,” he said.

The Expo’s $141,500 bill is actually lower than it might have been, Healy said. The district normally charges hookup fees for peak usage, which for the Expo would be fairtime when up to 92 RVs belonging to 4-H families stay at the RV park.

“In this case we’re willing to make exceptions” to the peak usage policy, Healy said.

Napa Sanitation is also offering the Expo a five-year payment plan for the older RV sites and waiving customary interest charges, he said.

As for Anderson’s reference to decommissioned kitchens, Healy said, “We have to see what’s out there and what they’ve added.”

The Expo operates on a $1.5 million budget, with the RV park expected to bring in $278,000 this year.

It’s too late for the Expo to raise ticket prices for this year’s fair, because presale tickets are already being sold online, Anderson said.

The $5,660 hookup fee for an RV site is the same as for a single-family house, Healy said.

Any customer that expands sewage discharge is charged for the extra demand on Napa Sanitation District’s collection and treatment facilities, Healy said.