With our first major winter storm, it is a good day to talk about flooding. This is not a problem limited to Marin, but is a possibility wherever people live near water. Where I grew up, in Trenton, New Jersey, the major streams had been buried and diverted since the 18th century. When the rain was heavy and the Delaware River filled, buildings flooded.
In Marin, heavy rains and runoff into our creeks can cause flooding in nearby neighborhoods. If the bay tides are high, the streams drain slower and flooding can be more severe. There have been only a few years of flooding in Marin. The Marin Sheriff’s Department has a short history. 1982 was probably the worst year, with 2005-06 next in severity.
I lived on the Arroyo Holon Creek (Baltimore Canyon) in Larkspur in 1982 when we had much rain and high tides. The house was on a beautiful sunny lot with redwoods and oaks and a bridge across the creek. Close to midnight, the water came up to my front doorstep, flooding the garden and basement. My electrical sump pump in the crawl space could not keep up, and then the power went out. Winds that often accompany winter rains had taken out a power line. The furnace was under the house. One cold night!
The next day the FEMA office gave me a check to replace the furnace. Two days later, I had a new furnace. FEMA also loaned me money to clean the massive debris out of the garden and creek and replace the broken bridge across the creek.
The severe flooding in the Baltimore Canyon creek happened primarily because of the accumulated debris in the creek Water pushed the tree trunks and random lumber up against the culvert that takes the creek under Magnolia Ave, causing the water to back up. Since that event, the creek is kept clean.
Areas that are prone to flooding in Marin are low-lying areas along creeks and marshy areas or filled marshes along the bay.
Is Your House in a Flood Zone?
The Federal Emergency Management Agency (FEMA) published new “flood maps” (FIRMS or Flood Insurance rate Maps) for Marin on May 4, 2009. These show the flood risks, if any, of every property in Marin.
FEMA has defined the flood hazard zones by the likely hood of flooding in the next 30, 100, 500 years, and so on.
- B, C, and X zones have low chances of flooding, and do not require flood insurance.
- A and V zones have a high risk of flooding in the next 30 years. Flood insurance is required for properties in these zones.
Much of the flood zone determination has to do with the number of feet a house is above a base flood plane (or elevation). Each community determines this elevation. It may be, for example, 9 feet. This sometimes results in a peculiar situation where part of a property is in the flood plane and part is above. However, if the house is above the base elevation, no flood insurance is required.
If you would like the official flood information on your house or another property, let me know. I’ll send you a mini flood map of the property.
What Can You Do to Prevent Flooding?
If you live in a flood hazard zone (A or V, contact me to find out), you have options to prevent flooding:
- Install a sump pump under your house. Also, consider a natural gas powered generator in case the power goes out. We have a great generator expert for you, Hazelton Electric, at www.hazeltonelectric.com. Many of our clients and friends have used their services to install back-up generators.
- Have sandbags ready to block the water at critical locations.
- Raise your house above the flood plane. Some cites now require this if you do a major remodel or if you build a new house. It is a small investment relative to your construction costs, and well worthwhile.
What is Marin Doing to Prevent Flooding?
There are many solutions completed and many underway. A few years ago, Novato completed a large flood control project on the Novato Creek that protected neighborhoods from flooding.
Corte Madera Creek Watershed, courtesy of the Friends of Corte Madera Creek
Towns along the Corte Madera creek, from Fairfax through Corte Madera to the bay, are ensuring unimpeded flow of the creek through developed areas. Creeks that drain easily are less likely to overflow. You can keep up to date with plans and ongoing programs at the Ross Valley Watershed website and the Friends of the Corte Madera Creek website.
Marin Mini-News
Community Garden in Marin City
The San Rafael-based Milagro Foundation, founded by rock star Carlo Santana, is sponsoring a community garden at the Martin Luther King Academy in Marin City. In cooperation with the Kellogg Foundation, this garden project will provide $65,000 a year for three years. Jessica Mullins reported on this program and the benefits to Marin City residents in the San Rafael News Pointer on January 13, 2010.
Conservation of Wetlands at Dillon Beach
The federal government has pledged $1M, to be matched by state funds, for conservation of hundreds of acres belonging to a campground at the mouth of Tomales Bay. Tim Henry provided an outline in the Point Reyes Light on January 7, 2010.
Marin Energy Authority Receives Support from San Anselmo
The controversy about establishing a Marin Energy Authority to provide a green alternative to PG&E continues in the county. The San Anselmo Town council affirmed its commitment on Jan. 6. Kelly Dunleavy reported the details in the Ross Valley Reporter on January 13, 2010.
