PAWHUSKA, Okla. (AP) — Eight months after fish and turtles died in an Oklahoma creek, when saltwater levels spiked and water temperature at the bottom of the creek hit 100 degrees Fahrenheit, there still isn't a definitive answer as to where the saltwater came from.

Contamination in North Bird Creek is likely from deep in the earth, Oklahoma State University geology professor Todd Halihan told the Tulsa World ( ).

Halihan said the answer may not be apparent, but water cools on its way to the surface, which indicates the saltwater may have come from deep underground.

"It's your standard murder mystery for hydrogeologists," he said.

The contamination has forced disgruntled landowners to move their cattle and horses for protection.

"I always thought if there was saltwater in a creek and a fish kill and the turtles are dead and all that, then everybody would be on it, but it's been a long time since August," said ranch manager R.D. Farr, who moved his horses and cattle away from the water.

Pawhuska has also moved its water supply out from Bluestem Lake to an older lake as a precaution, due to the unknown nature of the contamination.

"We will keep it that way until we know something different," said City Manager Mike McCartney.

District 6 spokeswoman Jennah Durant said the Environmental Protection Agency will continue to monitor the creek as they investigate the cause of the contamination.

"We understand the frustration over a long investigation into the source or cause of elevated (Total Dissolved Solids) levels," Durant said. "EPA's authority to compel corrective action requires a responsible party; in this case, no visible surface indications have indicated a source of this abrupt rise in TDS levels."

Durant said rain in the area has also curbed stream testing, most effective when the creek is at its lowest flow level.