Last month, board members of the San Antonio River Authority junked a plan to more than double its property tax rate so the agency could get into the business of Edwards Aquifer protection.

It was a bitter disappointment for San Antonio officials, who have been struggling to find new money to safeguard the aquifer. They’re also scouring for funds to complete the city’s “emerald necklace,” its system of creek-side parks and trails.

San Antonio Water System — and its ratepayers — have emerged as a possible Plan B.

Local officials are talking behind the scenes with the city-owned utility about taking on aquifer protection, according to sources familiar with the discussions. The proposal is serious enough that SAWS trustees are expected to get a briefing on it when they meet Tuesday.

Details so far are scant. But we know plenty of the backstory.

Mayor Ron Nirenberg, Bexar County Judge Nelson Wolff and other leaders are pushing to shift about $40 million in annual sales tax revenue from the city’s aquifer protection and linear park programs to the grossly underfunded VIA Metropolitan Transit.

In other words, they want to trade the purchase of conservation easements to prevent development in the Edwards Aquifer recharge zone — a program that safeguards the purity of the region’s largest source of drinking water — for more frequent and reliable bus service.

The issue is expected to go before voters next November.

There are a couple of catches. Propositions 1 and 2, which set aside a slice of local sales tax money for Edwards Aquifer protection and linear parks, have been wildly popular with voters — they’ve renewed the tax four times at the ballot box. And as a councilman representing District 8 in Northwest San Antonio, Nirenberg was a champion of aquifer protection and environmentalists’ go-to elected official.

The upshot: Officials want the aquifer and parks programs to continue. Just not with sales tax dollars.

“We all agree we have to find a way to do this,” said former Mayor Henry Cisneros, who’s co-chair of ConnectSA, the group developing a long-range transportation plan for San Antonio. “It’s not good enough to reallocate the one-eighth cent (sales tax) and then not have a way to continue the aquifer-protection program. … A number of options are on the table and under discussion.”

The issue arose because the tax that pays for Propositions 1 and 2 is set to expire next year.

For now, the city has maxed out how much sales tax it can charge consumers of everything from toothpaste to sports cars. To contribute more sales-tax revenue to VIA, one of the city’s other sales-tax-funded programs would have to take a hit. Which are you willing to give up — pre-K for 4-year-olds or easement acquisitions to protect the aquifer?

OK, the choice isn’t that difficult. In addition to the adorableness of little kids, providing them a solid educational foundation is one of the surest ways to lift San Antonio out of its status as one of the poorest big cities in the U.S.

So Propositions 1 and 2 get the heave-ho.

Then what?

Wolff said he’s focused on determining whether county government can come up with tax dollars to pay for more linear parks — and whether the five-member Commissioners Court that he presides over has the appetite to spend the money.

He said he’s not been privy to discussions about SAWS and aquifer protection.

Insiders’ attention, if not Wolff’s, is locked on SAWS in part because it once ran an aquifer-protection program similar to the city’s, though on a much smaller scale.

The utility started buying conservation easements above the Edwards in 1993, eventually accumulating 28,700 acres, nearly 20,000 of them in Uvalde County to the west of San Antonio. SAWS paid a total of $9 million and traded $2 million worth of property for easements.

SAWS ended the program after San Antonio voters first approved Propositions 1 and 2 in 2000, making its last acquisition in 2007.

So SAWS has history and experience with aquifer protection. But it also has huge expenses it wasn’t contending with back in the day.

They include the 142-mile Vista Ridge pipeline that will begin delivering water in 2020. The total cost of Vista Ridge, which is supposed to increase the city’s water supply by 20 percent, will be more than $2 billion.

SAWS also has a mandate from the Environmental Protection Agency to make $500 million in improvements to its sewage pipes over a 10-year period to prevent spills.

Its customers are getting pinched as a result. City Council in 2015 approved a series of rate increases — largely to pay for Vista Ridge and sewer upgrades. A 10 percent hike takes effect Jan. 1. The average residential bill will climb from $65.83 to $72.38.

All of that is on the operations side of the business. There are also political demands on SAWS.

City Hall squeezed an additional $10.8 million from SAWS for the 2019-2020 budget, raising the portion of the utility’s annual revenue that it has to contribute to the city’s general fund from 2.7 percent to 4 percent.

SAWS chief executive Robert Puente warned of future rate increases if city officials hold the utility to that bigger contribution in coming budgets.

And now there’s the possibility that SAWS will be called on to buy easements over the aquifer, which could push up rates further.

Puente declined to comment, and a spokesman for Nirenberg said: “The mayor is not commenting on funding the aquifer protection program until a path forward has been determined.”

There is, of course, another option for bankrolling aquifer protection: City Council could raise property tax rates to cover a portion of the lost Propositions 1 and 2 funding — a move that would probably trigger a rollback election. In other words, San Antonio voters would have a chance to weigh in on whether they want to pay more for aquifer protection.

My guess is that Nirenberg and the rest of City Council would rather see SAWS take the heat for a rate hike. That way, they avoid the political consequences of trying to raise taxes — as well as the risk that voters say no.

greg.jefferson@express-news.net