For thousands of years, water has percolated beneath southwestern Oregon's Siskiyou Mountains to form weird marble caverns with limestone chandeliers. Now, National Park Service officials say a neighbor's mining, logging and grazing may be altering the delicate chemical composition of the caves' water sources. The "neighbor" is the Siskiyou National Forest, which completely surrounds the 480-acre Oregon Caves National Monument.


Oregon Caves Superintendent Craig Ackerman says clearcutting and the use of herbicides during tree planting in the monument's watershed might be changing the acidity of water flowing through the caves. A significant change would disrupt the caves' formations and their subterranean ecosystem, and harm the habitat of the threatened big-eared bat, says Ackerman.


Although the Park Service has just begun to study the long-term impacts, the issue has come to a head because the agency is formulating a new management plan for the monument. According to Ackerman, the plan may call for an expansion of the monument's boundaries onto Forest Service land. A draft plan is expected by February 1997.


* Katie Fesus