Earlier this month, the Texas Commission on Environmental Quality issued a notice to a handful of East Texas groups in the Sabine River Basin: Their rights to river water will be suspended because a hunting and fishing club needs more water. The club's right to water predates the others' rights — literally.

The Sabine River notice is the latest development in what experts say is an unprecedented tug of war between surface water rights holders. Texans with more "senior," or long-standing, water rights can tell the TCEQ that they need more access to water, trumping "junior" rights holders along the same river, who may see their water use limited. And when drought makes water scarce, those senior rights prove to be critical.

"In modern history, at least as long as I've been paying attention, this is the first time it's really come to the fore," Russell Johnson, of the law firm McGinnis, Lochridge & Kilgore, said of the junior-senior system.

The oldest Texas water rights were claimed in the 18th century. "We have water rights that date all the way back to when Texas was a colony of Spain," said Andrew Sansom, executive director of the River Systems Institute at Texas State University.

Droughts in the recent past have triggered some "senior calls," but nothing like the current numbers. In 2011 there were 15 senior calls, according to Bryan Shaw, chairman of the TCEQ, in testimony before the Legislature last week. By contrast, only one such call occurred in 2009, another drought year.

All told, Shaw testified, more than 1,200 water rights permits in Texas have been suspended or curtailed recently, with the effects felt in the Brazos, Guadalupe, Colorado, Sabine and Neches river basins. With 99.5 percent of Texas still in drought as of last week, and with many reservoirs and rivers not replenished by the recent rains that have soaked into the thirsty soil, the junior-senior struggles could continue.

Groundwater, which is managed separately, is not on a junior-senior system.

Some groups have concerns with surface water hierarchy. "I got a few calls from industrial users who were adversely affected by this," Johnson said.

The recent decision in the Sabine River Basin will mean less water for a Wood County flood control project, as well as several groups who use water for recreational purposes and two individuals who use it for irrigation, according to the Longview News-Journal.

In the Neches River Basin, a range of water users has been affected, according to Andrea Morrow, a TCEQ spokeswoman. "Water rights that were completely curtailed included recreational uses, agricultural irrigation, industrial, and mining uses," she said.

The Texas system is not unusual. Doctrines of "first in time, first in right" are "almost universal west of the Mississippi," Johnson said. And the system has pros and cons, he noted. On the one hand, it protects people who have already been on the land against newcomers taking water the early birds had been counting on. On the other hand, the importance of the use is not taken into consideration.

Some changes are under way. Recently, the TCEQ decided that water rights holders couldn’t trump cities or power plants. This ensures that the taps keep running and power stays on. However, the TCEQ can ask cities that are "junior" to mandate outdoor watering restrictions. (This may have caused some of the confusion in the Hill Country town of Junction last summer, which thought it had to ban all outdoor watering after a senior call from the downstream city of Llano but later was able to ease off.)

"Sunset" legislation last year reauthorizing the TCEQ and its mission contained a provision that allows the agency to suspend or make changes to the water rights system during times of drought. Comments on a proposed rule to implement the law closed last month — and it's something the Texas Farm Bureau is watching closely, said Billy Howe, the bureau's representative in Austin.

Sansom, of Texas State, says that another classic example of "oldest first" is the struggle in Central Texas between rice farmers, growing cities like Austin and residents of the severely depleted Highland Lakes (though this system, managed by the Lower Colorado River Authority, goes beyond and is more complex than the "junior-senior" rights hierarchy overseen by TCEQ). Rice farmers have been using Colorado River water since the 19th century, even before the Highland Lakes were created — and in normal years a few hundred farmers use more water than the city of Austin.

Speaking about both the LCRA situation and the junior-senior rights system, Sansom said, "It is probably time, based on the fact we're still using a system that is hundreds of years old, to update it to reflect modernity."