Frequently Asked Questions

Not much really.  Originally, Comprehensive Storm Drains (CSDP) were to cover storm drain systems which are often not regional but local in nature.  Master Plans of Drainage (MPD) tend to be of a larger scale and focus on regional facilities.

A MPD is a coordinated plan of flood control improvements for an area/community/city based its future planned development. The plan identifies existing flood control facilities which are inadequate to convey the 100-year peak storm flows, existing facilities needing improvement and new facilities which need to be constructed. In addition, MPD provided construction priorities for facilities based on needs and preliminary planning costs.

Although a 100-year storm event is considered as being equaled or exceeded in size, on the average only once in every 100 years, it has a one in 100 (or 1%) chance of occurring at any time during a year. The ultimate regional facilities of the Flood Control District are designed and constructed to convey the 100-year storm event flows, or Q100. Similarly, a 50-year storm event has a two in 100 (or 2%) chance and so on.

Due to the expanse of area, climate and topography, the Flood Control District was divided into six zones, with interests, responsibilities or geographical divisions distinct of the particular zone. Each zone functions independently but may enter into mutual arrangements with other zones. Revenues collected from each zone must be expended within that zone.

The primary source of funding for the Flood Control District is property taxes. Additional fees may be levied by special assessment and for development. Some additional funds are generated from permit fees, leases, surplus property sales, and federal and state reimbursements. In addition to the geographic zones, there is an overall county-wide administrative zone with its own property tax source, for general administration and equipment.

The Flood Control District defines a regional facility as a structure which has a watershed of at least 640 acres OR is constructed to convey at least a Q100 of 750 cubic feet per second of storm flow. This distinction was made to separate local storm drain facilities from larger projects. The District mission is to focus funding and efforts on regional facilities which act as the “backbone” for the secondary and local facilities to connect to. Secondary and local facilities are often built and maintained by the Cities.

In most cases, SBCDEs are granted as means for the County to direct flows under roads without causing any erosion upstream and/or downstream.  These easements allow the County to enter onto private property for the purposes necessary to control flows within the easement areas and preclude the owners from building within them without the County’s approval.  Any public improvements constructed within a SBCDE would be maintained by the County, most likely the Road Department and very few SBCDEs have improvements constructed on them.  If the County has never done maintenance within a SBCDE then it most likely does not have an obligation to do so.  It should be noted that the Flood Control District (District) has no right or obligation to work within a SBCDE.It also should be noted that the vast majority of the SBCDEs offered to the County fall into one of the following categories:

  • Rejected outright, where the County has no rights to enter the property without first going through a Board of Supervisors acceptance process.
  • Accepted but no obligation for operation and /or maintenance is accepted, where the County has no obligation to do work.