This story was originally published by The Texas Tribune, a nonprofit, nonpartisan media organization that informs Texans — and engages with them — about public policy, politics, government, and statewide issues.
The Rio Grande is no longer a reliable source of water for South Texas. That’s the sobering conclusion Rio Grande Valley officials are facing as water levels at the international reservoirs that feed into the river remain dangerously low — and a hurricane that could have quenched the area’s thirst turned away from the region as it neared the Texas coast. Although a high number of storms are forecast this hurricane season, relief is far from guaranteed as the drought drags on. For now, the state’s most southern cities have enough drinking water for residents. However, the region’s agricultural roots created a system that could jeopardize that supply.
Cities here are set up to depend on irrigation districts, which supply untreated waters to farmers, to deliver water that will eventually go to residents. This setup has meant that as river water for farmers has been cut off, the supply of municipal water faces an uncertain future. This risk has prompted a growing interest among water districts, water corporations, and public utilities that supply water to residents across the Valley to look elsewhere for their water needs.
But for several small, rural communities that make up a large portion of the Valley, investing millions into upgrading their water treatment methods may still be out of reach. A former channel of the Rio Grande, or resaca, winds through agriculture fields near Los Fresnos, on Wednesday. The Rio Grande Valley is facing a drought, greatly affecting farmers in the region. 
A new water treatment facility for Edinburg will undoubtedly cost millions of dollars, but Tom Reyna, assistant city manager, believes the high initial investment will be worth it in the long run. “We see the future and we’ve got to find different water alternatives, sources,” Reyna said. “You know how they used to say water is gold? Now it’s platinum.”
For Edinburg, one of the fastest growing cities in the Valley, the need for water will only grow as its population does. While the city hasn’t faced a water supply issue yet, the ongoing water shortage in South Texas combined with the growing population has put local officials on alert for the future of their water supply. The Falcon and Amistad International reservoirs feed water directly into the Rio Grande. And while water levels have been low, cities and public utilities have instituted water restrictions that limit when residents can use sprinkler systems and prohibit the washing of paved areas.
Cities have priority over agriculture when it comes to water in the reservoirs. Currently, the reservoirs have about 750,000 acre feet, of which 225,000 acre feet are reserved for cities. Jim Darling, chair of the Rio Grande Regional Water Planning Group and former McAllen mayor, points at rivers and tributaries shown on a map at the South McAllen Water Plant, in McAllen.
Of those 225,000 acre feet, each city or public utility or water supply corporation can purchase what are known as “water rights” which grant permission from the state to use that water. But without water for farming, more and more of the water that cities own is being lost just in transporting the water to their facilities, and that’s directly due to the loss of water for farmers. This relationship with the agriculture industry arose because irrigation districts were created here first. Cities came after, and because they used less water, they were set up to depend on irrigation districts.
Water meant for residential use rides atop irrigation water to water treatment plants. Without irrigation water, cities start to use water they already own to push the rest of their water from the river to a water treatment facility. It’s referred to as “push water.” Much of that water is lost for this purpose. When water levels at the reservoirs got dangerously low in in the late 1990s, the average city would only get about 68 percent of the water it owned because the rest would be used as push water, according to Jim Darling, board member of the Rio Grande Regional Water Authority and chair of the local water planning group, a subset of the Texas Water Development Board. 
Filtered groundwater is desalinated through reverse osmosis at the Southmost Regional Water Authority brackish groundwater treatment facility in Brownsville, Texas. Eddie Gaspar/The Texas Tribune
The board is tasked with managing the state’s water supply. Darling, a former McAllen mayor, has been trying to get cities to think of ways to increase their water supply. As cities try to temper water demand by issuing restrictions on water usage, Darling said public utilities need to think about the drought not just from the standpoint of managing demand but also by increasing supply.
Darling has been floating the idea of creating a water bank of push water so that water districts can get by without having to go through the process of obtaining approval from the state for more water. These discussions have been ongoing with the watermaster from the Texas Commission on Environmental Quality, who ensures compliance with water rights. The talks are still preliminary, but a conversation with the watermaster’s office in early July revealed that three or four of the Valley’s 27 irrigation districts were out of water. “Something needs to be done,” Darling said.
Edinburg’s proposed water plant is still in the early planning stages, but the goal is to stave off water woes by turning to water sources underground. The plan is to dig up water from the underground aquifers as well as reuse wastewater. The two sources of water would be blended and treated through reverse osmosis. Reverse osmosis consists of pushing water through membranes, large cylinders that filter the water. This is done several times until the water is pure and meets drinking water standards set by the Texas Commission on Environmental Quality.
This method isn’t new. By implementing this practice, Edinburg is following in the footsteps of the North Alamo Water Supply Corporation, a utility that supplies water to eastern Hidalgo County, Willacy County, and northwestern Cameron County. Members of the public listen to Cameron County Judge Eddie Treviño Jr. as he begins to lead a water conservation meeting with various stakeholders across the Rio Grande Valley at the county courthouse in Brownsville. Eddie Gaspar/The Texas Tribune
After the drought in 1998, North Alamo turned to reverse osmosis in the early 2000s. Its facilities currently treat about 10 million gallons of water per day through reverse osmosis, which represents one-third of all the water it treats. The rest is surface water from the river, but the utility aims to switch that split, treating two-thirds through reverse osmosis and only a third of surface water. “We’ve got that mindset that we have to get away from the river,” said Steven P. Sanchez, general manager of North Alamo. “We have to start going to reverse osmosis.”
Hidalgo County officials are trying to take a more “innovative” approach to the area’s water problems. In April, county officials touted a proposed regional water supply project, dubbed the Delta Water Reclamation Project, that would capture and treat stormwater to be used as drinking water. The project, expected to cost $60 to 70 million, started off as a project to mitigate flooding by drawing water away from a regional drainage system. But now, plans include a water plant that would take daily runoff and treat it through reverse osmosis.
“We are the first drainage district to do something like this and of course that’s an exciting thing for us, to be able to do something that’s so innovative and green,” said Hidalgo County Commissioner David Fuentes, who sits on the drainage district board. “But it comes with a lot of obstacles and a lot of unknowns.”
One challenge will be financing the water plant. Drainage districts are limited on the bonds they can issue in exchange for a loan. Obtaining funds from the Texas Water Development Board would also be an uphill battle since a drainage district doesn’t fit the usual metrics that a water supply corporation does. County leaders made the case for their project before a Texas Senate committee hearing in May.
