"Principal county" means the county in which all the land is situated, or if the land is situated in more than one county, the county in which the greatest portion of the area of the land is situated.
In proceedings for consolidation or reorganization of districts having different principal counties, the term "principal county" means the county in which the greatest portion of the total combined acreage in the districts to be consolidated or reorganized is located.
Ca. Water Code § 20518