California Code, Water Code - WAT § 43850

(a) Attacking the organization of any district, within six months of the date of the organization thereof.

(b) Attacking the inclusion of land within or the exclusion of land from any district, within six months of the date of the inclusion or exclusion.

(c) Attacking any assessment of any district, within 60 days of the date upon which the assessment roll is filed with the county treasurer or treasurers.

(d) Attacking the validity of any bonds issued by any district, within 60 days of the date of adoption of the resolution providing for the issuance of such bonds.