Flood Control Zone 9 was formed in the early 1950s to provide funding for construction and maintenance of regional drainage infrastructure in the Pinole Creek watershed. It initially provided, from a portion of the ad valorem property tax, local matching funding for a joint District / Army Corps of Engineers project extending from the mouth of the creek up to Highway 80.
Prior to the passage of Proposition 13 in 1978, Zone Boards, which consisted of representatives from the watersheds, adjusted the tax rates of each Flood Control Zone annually. When Proposition 13 came around, several of the zone facilities were constructed, maintenance was up to date and there was enough money in the funds to set the tax rate very low or at zero. Upon passage, Proposition 13 froze those tax rates, in effect shutting off the tax revenue needed to adequately fund the maintenance of the Zones’ flood control facilities.