A type of known loss provision, a Montrose provision in a liability policy
restricts coverage for damage that occurs over multiple policy periods to those
policies in which the insured was not aware of the occurrence at the inception
of the policy period. The term "Montrose provision" is derived from
the 1995 California Supreme Court ruling—Montrose Chem. Corp. v. Admiral
Ins. Co., 10 Cal. 4th 645, 42 Cal. Rptr. 2d 324, 913 P.2d 878 (1995)—that
allowed recovery for damages even after the insured was aware of the loss,
because the full extent of the loss was not yet known.