SAN JUAN CAPISTRANO — Bill Bathgate planted his feet gingerly on the raw edge of Oso Creek and pointed down its steep bank.
"See that orange tree?" Bathgate said, motioning toward a tree that had toppled to the creek floor. "Two months ago that was part of the orange grove. You can see it's just beginning to wilt. See that eucalyptus? It slipped down, too."
Bathgate, 66, has spent his life on this citrus, avocado and persimmon ranch where the normally quiet Oso and Trabuco creeks converge--long enough, he says, to speak with authority of the development that has crowded out most of the other small farmers in the area.
And now, thanks to the water runoff from residential and commercial development in Mission Viejo and other communities farther upstream, Bathgate says erosion along Oso Creek is literally stripping farmers of their land before their eyes.
Bathgate says what is happening on the ranch--he recently sold it to the Schuller Ministries but still lives there--is an example. In the midst of an orange grove, where the creek makes a sharp right turn just to the west of Interstate 5, erosion from fast-flowing water runoff has begun to carve out a canyon now an estimated 50 feet deep.
Roots of undermined trees poke out of the creek banks and other trees lie strewn on the creek bottom, all the victims of the rushing water and expanding creek.
"I can remember when this creek was about 6 feet deep and 6 feet wide," Bathgate said. "I used to be able to drive my truck across it in some places."
Bathgate said the problem rests with the thousands of homes built between San Juan Capistrano farms and the twin Saddleback peaks, source of the small tributaries that form Oso Creek. The creek gathers force as it descends among the new black-topped developments and the man-made Lake Mission Viejo to the Saddleback Valley floor.
Just as with the larger sister creeks of Trabuco and Santiago, that flow has intensified with development, said Jim Williams, a flood control engineer for the county's Environmental Management Agency.
"More of the watershed is now made up of paved roads, roofs and other impervious surfaces," Williams said. "These things impede percolation so, even though the rainfall is the same, more of it runs off and the rate of flow is faster."
That rate increases as it hits the valley floor, crosses over the county's patchwork of concrete erosion and flood control channels and then dumps out into the unprotected sandy soil next to the Bathgate ranch.
Ignacio Lujano, 67, has worked on the farms in this part of the Capistrano Valley since 1958. He has watched the waters do their damage, the results of which often do not show up until months later.
"I remember when this was just a little creek," Lujano said. "But the water keeps digging, digging. There is no other place for it to go."
The water may come from upstream, but the problems develop on private property, and officials say there is little they can do.
"I believe our rights are limited in that area," said Bill Reiter, a public works operations manager for the Environmental Management Agency. "If we don't own anything in the area, it would be a landowner's responsibility. . . . We have very limited flood plain easements. The only time we are obligated is when flooding is imminent."
Experts also note that the creek is an established wildlife habitat, further impeding any substantive corrective measures. Small animals such as raccoons, skunks, coyotes, opossums and rabbits abound in the area.
Bill Huber, the director of public works for the city of San Juan Capistrano, says talks with the county to correct creek problems in the city have begun. He noted that Oso Creek also flows through property the city has considered purchasing to preserve as open space, and the city wants to avoid any further problems with erosion.
"We're looking at some time in the future of improving that channel in such a way that maintains a natural appearance and provides protection to property owners," Huber said. "Ultimately it becomes a joint problem between the city and county flood control district. This kind of work is not cheap. A couple of miles of cement lining for a channel like this can cost $10 million to $15 million easily."
Wendy Wetzel, a spokeswoman for the Mission Viejo Co., one of the major developers in the Oso Creek watershed, said steps have already been taken to control the downstream flow. The Mission Viejo Co. built three major water retention basins, including the Upper Oso Reservoir, to catch water that otherwise would have wound up passing through the Bathgate farmland.
"Our engineers tell me Oso Creek has more water retention facilities than any other comparative watershed," Wetzel said.
No matter who is liable, something must be done to lower Oso Creek or "one of these days there will be enough water running through there to straighten out the creek and make a wasteland of that property," said William W. Knitz, general manager of the Santa Margarita Water District.