More disasters like that at the Kesterson National Wildlife Refuge could occur if the California Water Resources Control Board approves a $1-million state loan for construction of new farm waste water evaporation ponds in the western San Joaquin Valley, federal biologists and environmentalists warned. The Tulare Lake Drainage District wants the loan to build 715 acres of new evaporation ponds despite the discovery of bird mutations and deaths at existing evaporation ponds in the region. The U.S. Fish and Wildlife Service warned in a letter that new ponds could violate the federal Migratory Bird Treaty Act, which triggered the closure of the Kesterson refuge in western Merced County. Selenium poisoning at Kesterson during the early 1980s triggered the worst bird deformities and mutations ever recorded, effectively halting a plan to build a master drainage canal for western valley farm wastes.