By Daryl Kelley
First came ferocious winds and killer freezes, then this week's devastating firestorms. This has been a year of cataclysmic natural disasters for Southern California. And now comes a stealth invader that could add enormously to the toll for 2007.
The quagga mussel, a pernicious and prolific mollusk that overwhelms freshwater lakes like Lake Casitas, poses such a threat to fisheries and waterworks that the state enacted an emergency law this month allowing lakes to be closed to boaters altogether and contaminated