ALLENTOWN, Pa. (AP) -- Work on a natural gas pipeline project remained shut down Thursday after drilling mud twice spilled into a northeastern Pennsylvania stream.

The state Department of Environmental Protection said it has not detected any impacts on aquatic life from the spill into Laurel Lake Creek in Susquehanna County, but would continue monitoring the high-value waterway. There was no estimate on when the pipeline work would resume.

Pipeline company Laser Northeast Gathering Co. LLC told environmental regulators that 1,400 gallons of drilling fluid were released in separate incidents on Friday and Tuesday, with all but 35 gallons recovered, DEP spokesman Daniel Spadoni said Thursday. Amateur video posted online showed pools of a thick, chocolate-colored substance impounded by sand bags.

Laser said the drilling fluid contained 95 percent water and 5 percent bentonite, a non-toxic clay.

The company is laying a 33-mile pipeline to transport natural gas from northern Susquehanna County to the Millennium interstate pipeline. Crews were tunneling underneath Laurel Lake Creek when what the industry calls an "inadvertent return" of drilling mud occurred.

Kevin R. Marion, Laser's director of pipeline engineering services, said the mud was forced to the surface through existing fissures in the rock. The company is considering a soy-based additive that is "supposed to help in this type of situation to plug fissures," he said.

He likened the spill's impact on the creek to that of a heavy rainfall, in which the water is muddy for a day or two then clears.

Craig Stevens, a Silver Lake Township resident who lives along Laurel Lake Creek downstream of the spill, wasn't buying it.

"All they did was run down the creek and throw some hay bales. The mud is going right through the hay bales," said Stevens, an outspoken critic of gas drilling. "That's their 21st century answer to destroying my creek? Is that all they got?"

Anti-drilling activists plan to walk Friday from Salt Springs State Park, which is fed by Laurel Lake Creek, to the spill site a few miles away.