Monday, 05 November 2007 01:09

Scientists Searching for Answers Around Tiger Creek Canal

Biologists are searching for answers as an unprecedented number of bears and mountain lions have drowned in what is known as the Tiger Creek Canal. The flume in the North Fork of the Mokelumne River is owned by the Pacific Gas and Electric Company who has documented that from mid-September to mid-October, 15 bears and two mountain lions have drowned.  According to Paul Raquel, a senior biologist supervisor for the California Department of Fish and Game who was hired by PG&E to help investigate the deaths, "It is an unusually large number of animals that have been lost." He and other biologist are finding few clues for what could be the cause for the record numbers.

The drowning deaths of bears who are known to be intelligent, cautious creatures that can swim - is particularly striking because PG&E spokeswoman Nicole Tam revealed that not a single bear has drowned in the flume in the three years before Sept. 14. Also, adding to the perplexity is the fact that the flume is fenced on both its uphill and downhill sides to keep animals from straying into the fast-flowing water. The Tiger Creek Canal, is an open, straight-sided, man-made, above-ground ditch that carries water 18 miles from Salt Springs Reservoir to Tiger Creek Regulator, a narrow reservoir after bay used by PG&E as part of its hydroelectric generation operations.

The flume is a little more than 14 feet wide and 7 feet deep. It flows at a rate of 550 cubic feet per second when it runs at capacity. PG&E acknowledges that some animals do occasionally die in the fast paced flume and that is why they keep statistics on the deaths as well as write an annual report. It is that documentation that revealed this year’s unprecedented numbers.  Raquel told the Stockton Record that there were a few places along the flume where mounded dirt or other debris would make it easier for animals to climb from the downhill side onto the flume's ledge and that is probably how at least one of the bears ended up in the flume. Tam said the bears were found dead on a grating that removes debris from the water before it enters a tunnel. Such gratings prevent debris from clogging the tunnel, Tam said.

Tam revealed one biologist speculated that the bear deaths might have something to do with bear hunting season, which opened in that area Sept. 22 and continues until Dec. 30. Tam also added that there have been no additional dead bears discovered since Oct. 15. "It was really just that one period of time. It is really strange," Tam said. However, the number is alarming and PG&E has taken new measures to prevent animals from being able to contact the flume. They have installed new fencing on the downhill side of the flume where mounded debris might make it possible for animals to gain entry. Raquel also added that biologists also are considering mounting cameras in some spots and have asked PG&E to provide the remains of any additional bears that turn up for a necropsy that might reveal any injuries.