FULTON — The whooping crane, the majestic bird slowly making its way back from the brink of extinction, is returning to the Texas coast in record numbers, with as many as 300 expected.

This could be a hard winter for the endangered species, however, because a severe drought has left the marshes saltier than usual and without the abundance of plump blue crabs they like to eat.

Working in pairs, the cranes can be seen all along the shores of the Aransas National Wildlife Refuge, rooting through the mud and coming up empty.

These conditions, made worse by a toxic algae bloom in the Gulf, could bolster a federal lawsuit filed by a local group against Texas over how much water is needed to sustain the species.

The outcome of the case, which goes to trial Monday, could further limit the allocation of water in the basins of the San Antonio and Guadalupe rivers and ultimately affect San Antonio water and energy customers.

The drought, the worst one-year event on record, has decreased the flow of fresh water from the rivers into the marshes and bays where the cranes congregate for the winter before flying 2,500 miles back to their summer breeding grounds in northern Alberta, Canada.

Some biologists say the conditions in Texas this year remind them of late 2008, which was the beginning of the deadliest winter on record for the flock.

As many as 23 cranes perished then, nearly 8 percent, which was the largest die-off ever recorded, according to the U.S. Fish and Wildlife Service. Those deaths prompted the suit against the state in federal court.

That suit, which pits environmentalists and the local governments and businesses of Aransas County against the Texas Commission on Environmental Quality and water suppliers, will be tried in Corpus Christi, about 40 miles from the refuge.

The Aransas Project, an environmental coalition, has accused the state of putting the cranes in harm's way with its management of the fresh water flowing into the birds' habitat.

“The future of the whooping crane hangs on the outcome of the trial,” said Jim Blackburn, the Houston attorney for the Aransas Project. “Federal intervention is the only chance for its long-term survival.”

The TCEQ, which governs the rights to the state's fresh water, and other water providers are fighting to maintain the status quo, saying there's no evidence of major losses caused by a drought three years ago.

Blackburn thinks what is needed is a holistic re-evaluation of how the state allocates water rights in the San Antonio and Guadalupe rivers, which supply the vast majority of the fresh water to the estuaries and marshes where the cranes feed.

That also would help protect the commercial and recreational fishing industries, on which the economy of Aransas County depends.

But more water for the bays would mean less water for upstream users.

Competition for water

One is CPS Energy, which gets the cooling water for its power plants from the San Antonio River. By state law, it can draw water until the river is reduced to 10 cubic feet per second, less than 10 percent of its normal flow.

That doesn't leave much water for the bays and estuaries and is the type of permit the TAP lawsuit aims to change.

CPS filed to intervene in the suit on behalf of the state but was denied. The same was true for the San Antonio Water System.

As the largest residential water provider in the region, SAWS thinks any more restrictions on water use could be an obstacle, even if an indirect one, said the utility's lawyer, Steve Kosub.

SAWS draws from the Edwards Aquifer, but several times it has tried unsuccessfully to obtain water from the San Antonio and Guadalupe rivers, and if TAP wins, that would further limit its chances.

A ruling in the lawsuit also could adversely affect SAWS' recycled water. Some of the treated water that comes from SAWS' sewage treatment plants is discharged into the San Antonio River and some is sold as recycled water for irrigation and industrial uses.

One possible outcome of the suit would limit the amount of recycled water SAWS could sell and increase the amount it would have to put in the river for downstream users.

The power of the Endangered Species Act, on which TAP is relying for its suit, is not to be underestimated, Kosub said.

In 1991, the act was at the center of a similar lawsuit filed to assure water for endangered species dependent on the springs in San Marcos and New Braunfels.

That suit triggered the creation of the Edwards Aquifer Authority and put limits on water use extending from Uvalde County to Hays County. It forced San Antonio to launch an extensive conservation program and start outdoor watering restrictions.

Harm from red tide

About the TAP lawsuit, the TCEQ asserts that the state already has a process in place to reserve water for bay and estuary needs. However, its authority is limited because state law requires the agency to respect existing water rights when establishing so-called environmental flows.

TAP argues that as it is, the existing water rights are causing the harm and therefore the state's process will do little to protect the cranes.

White with black wingtips and crimson crowns and standing 5 feet tall, the cranes started to arrive in Texas in mid-November, with the rest expected by Christmas. They are part of the only self-sustaining flock in the world. The number of cranes dipped as low as 15 in 1945, and they were declared endangered in 1970.

Their arrival comes at a time of widespread fish kills in the bays caused by the algae bloom, known as red tide. This year's bloom is so severe that even humans on shore are getting headaches and running noses. Fish are floating belly up across the bays and can be seen along the shoreline.

Cranes' diets include few fish. But if this year the cranes have to eat a lot of dead fish to stay alive, they too could die, according to Dan Alonso, manager of the Aransas refuge.

“It's killing birds as we speak,” he said about other seabirds that have been collected after dying from eating tainted fish.

Even in the bait shops, fish are dying because of the toxic water circulated through tanks. The blue crabs are so scarce that their tanks sit empty, and commercial fishermen have taken most of their pots out of the water.

“San Antonio Bay has just turned off this year,” said Leslie “Bubba” Casterline, owner of the Casterline Fish Co. and an Aransas County commissioner. “It's almost sterile.”

Without heavy rainfall, the cranes may not find any crabs between January and March, following the deadly pattern of three years ago, Blackburn said.

“The only thing I have seen them eat is dead fish,” said Tommy Moore, who gives daily boat tours to see the cranes out of Fulton.

Moore supports the TAP lawsuit and provides brochures about it to his guests.

An opponent of the lawsuit, the Guadalupe Blanco River Authority, which is the largest water rights holder in the basin, asserts the cranes are thriving on the Texas coast. According the Bill West, GBRA's general manager, TAP cannot prove 23 whooping cranes died in 2008 because only four carcasses were found and the rest are simply “missing in action.”

It also argues that TAP can't link the deaths and high salinity because a Texas A&M University study, paid for by GBRA, shows the cranes are opportunistic foragers, able to survive when blue crabs are in short supply. They also eat wolfberry fruit, insects, snails and fiddler crabs.

To help the cranes this winter, the federal refuge's managers plan to burn at least 9,700 acres, an act that should expose food items, Alonso said. The managers also are eliminating hiding spaces for the cranes' predators by mowing down dense brush around ponds and stock tanks where the birds drink.

“In the midst of drought and red tide,” Alonso said, “we're hoping for better conditions.”