Austin and a major water authority are lining up to oppose a request to allow discharging sewage effluent into the Highland Lakes.

On Thursday, the city could join Travis County and the Lower Colorado River Authority in formally opposing a petition by the cities of Leander and Granite Shoals that asks the Texas Commission on Environmental Quality to end restrictions on discharging effluent into the Highland Lakes, which include Lake Travis.

Hays County is also expected to formally oppose the request today. Travis announced its opposition last month.

In a petition filed in late September, Leander and Granite Shoals said that adding effluent into the Colorado River basin, rather than pushing it underground in septic tanks or spraying it on fields for irrigation, will alleviate the escalating crunch on water supplies in the Colorado River basin. They have also argued that treated, discharged effluent is of higher quality than water already in the lakes.

On Friday, a memo by Richard Hyde, deputy director of the office of permitting and registration for the environmental agency, recommended that commissioners deny the petition but that they set up a public process to "examine the framework for water quality protection in the Highland Lakes watersheds, which may include modifying the Highland Lakes watershed rules."

A draft of a resolution that the Austin City Council is likely to approve Thursday says Austin opposes the repeal of the restrictions because the city gets its drinking water from the lakes, among other reasons.

Austin City Council Member Chris Riley, who is sponsoring the resolution, said Leander and Granite Shoals should use the treated effluent to further irrigate land or use in toilets in commercial buildings.

"That way we avoid potential impact on water quality and preserve the recreational value and safety of the water in the Highland Lakes," he said.

In comments submitted Friday, LCRA officials argued that "emerging contaminants" such as pharmaceuticals, which might not be filtered out by the wastewater treatment plants, could make their way into the lakes.

And the river authority argued that repealing the ban would not significantly increase water supply.

A repeal of the restrictions would allow Leander and Granite Shoals, fast-growing cities in Williamson and Burnet counties, to develop more easily because it would bring down the cost of treating sewage, according to the petition. Granite Shoals, located on Lake LBJ, says it would have to spend millions to purchase and develop irrigation fields and distribution systems.

"As lakeside communities on two of the Highland Lakes, Granite Shoals and Leander are pursuing this rule change to improve the water quality and to stop the needless waste of water by disposal irrigation," said Granite Shoals Mayor Frank Reilly. He said they would welcome a public process that would lead to "a more rational rule-making framework for the Highland Lakes."

The state environmental commissioners are scheduled to take up the matter Nov. 18.