2009 California Fish and Game Code - Section 2250 :: Article 2. Mammals

2250.  It is unlawful to import or transport into or possess any
live muskrat (genus Ondatra) in California except under permit issued
by the department pursuant to Section 2118, or as otherwise provided
by law. A county agricultural commissioner, fish and game deputy, or
state plant quarantine officer may enter upon lands or waters west
of the crest of the Cascade-Sierra Nevada mountain system, and west
and south of the Tehachapi, Liebre, San Gabriel, San Bernadino, San
Jacinto, Cuyamaca, and connected mountains south to the international
boundary, or in any watershed tributary to, or draining into, the
Pacific Ocean to remove or destroy the muskrats.