Jul 29, 2014

New Flood Maps Come With Building Restrictions

FEMA draft flood maps will create property expansion limits and change flood insurance requirements and rates. We have information to help you read the maps and figure out how your property is impacted.

New Flood Maps Come With Building Restrictions New Flood Maps Come With Building Restrictions New Flood Maps Come With Building Restrictions New Flood Maps Come With Building Restrictions


Thinking about expanding your home, getting a hot tub, building a deck or fence or doing other upgrades on your Ross Valley property?

You better check out the recently released draft maps designating new flood-risk areas.

If your land falls into new high-risk zones, you may want to expedite your property plans before the maps are approved next year; homes that fall into the newly designated “floodways” will face future development and expansion restrictions.

The FEMA (Federal Emergency Management Agency) regional flood insurance rate maps, updated from what was last released in 2009, may also change property owners’ insurance requirements and rates.

Some frustrated with the map changes

“Ross Valley is actually one of the most flood prone areas in the state of California,” FEMA Engineer Kathleen Schaefer told a crowd of more than 100 residents and community members who filled the community room at Sir Francis Drake High School recently for an informational meeting about the draft maps. Since 1978, there has been $22.5 million in loss claims filed from Ross Valley to the National Flood Insurance Program, Schaefer said.

At the meeting, a few didn’t hesitate to express some frustrations and concerns about the new maps’ prospective repercussions.

Fairfax resident David Leonard wasn’t happy that his home fell into the “high-risk” flood zone.

“I’ve been living on this property for over 40 years and it’s never flooded in the 200-year floods. I’ve never had any flooding,” he said.

Ryan O’Neil, a Fairfax councilman, asked about the building restrictions people in the new flood zones will face. “How do they plan for their future? This affects people on a very deep level.” 

The draft maps were released largely so people can have a “heads up” about changes they may be facing, Schaefer said. “If you are located within a special flood hazard area and you are in the floodway, you will be subject to restrictions.”

She said those residents should contact city officials (we have contact information below) if they have expansion or building plans. “Tell them what you are planning to do to see if these do, in fact, affect you or not. If you are planning on building within the existing footprint, it’s very likely these won’t have a significant affect.”

At the June 28 meeting, residents examined topographic work maps (attached above) showing boundaries of the new flood zones along Corte Madera Creek and in Mill Valley.

When the revised maps are released this fall, tentatively scheduled for September 2012, it will trigger a formal review and comment period before all the town and cities adopt the maps. “The whole process takes a year,” Schaefer said.

Planning on building on your property?

  1. Study the FEMA draft topographic maps (attached above) to determine if you live in a flood zone. Use the map definitions below (or attached above as a PDF) to help you read the maps.
  2. In a high-risk flood zone or floodway? Contact your local town officials:
  • San Anselmo Department of Public Works Project Manager Gerhard Epke at 258-4653
  • Fairfax Building Official Mark Lockaby at 458-2370


Moderate to Low Risk:

B and X (shaded): Area of moderate flood hazard, usually the area between the limits of the 100-year and 500-year floods. 

C and X (shaded): Area of minimal flood hazard, usually depicted on FIRMs as above the 500-year flood level.


High Risk:

A: Areas with 1% annual chance of flooding and a 26% chance of flooding over the life of a 30-year mortgage.

AE: The base floodplain where base flood elevations are provided. 



1% Annual Chance: 100 year flood (AE Zone). If you live in a 100-year floodplain, there is a 26% chance of flooding over the life of a 30-year mortgage.

.2%  Annual Chance: 500 year flood (shaded X Zone)

BFE: Base Flood Elevation

DFIRM: Digital Flood Insurance Rate Map

FIRM: Flood Insurance Rate Map

Floodway: A "Regulatory Floodway" means the channel of a river or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height.

Flood Hazard Inundation-: Areas subject to flood. These are new areas or areas that have changed (BFE has been established).

LOMR: Letter of Map Revision by which the map has physically changed to reflect better/updated data.

Tie-Ins: Areas where the flood zone has not changed since last the FIRM. Includes the new flood data into the data that did not change.


For more information


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