600 Series - Flood Warning and Response

Section 610

(395 points)
San Anselmo has a multifaceted flood warning system and multiagency response plan, codified in the Winter Storm Emergency Procedures document. Additionally, San Anselmo and the State of California both have Emergency Response Plans based upon the Standardized Emergency Response Management System. Flood warning and response is closely coordinated with Marin County Public Works staff from our Flood Control District.

San Anselmo is under the jurisdiction of Central Marin Police Department and Marin County Sheriff's Office of Emergency Services (OES).
Link: Marin County Sheriff OES description

On January 8, 2013 San Anselmo Town Council received a report from the Town Manager about Winter Storm Emergency Procedures. This report explains the nature and history of flooding and names 5 stages of flooding in the creek based upon the gage downtown. Each stage calls out certain actions by different coordinating departments. This includes when to sound the flood horn, and send automated telephone messaging systems. The report also analyses creek stage information, specifically the maximum rate of increase ever measured. San Anselmo and Sleepy Hollow Creeks are such small watersheds, ~14 square miles, that rainfall runoff lag times are on the order of 1.5 to 3 hours, with rates of increase around 6 feet per hour. This document addresses most of the 611 credit criteria. Flood inundation areas at five recurrence intervals are linked to on San Anselmo’s Flooding and Storm Resources webpage, under “Flood Maps and Insurance Information”.

Staff Report San Anselmo Town Council 1/8/2013 and attachments
Minutes from above meeting
Real-Time Creek Level Gauge

San Anselmo Emergency Operations Plan (photo)
Ross Valley Fire Department Severe Weather Operations
Ross Valley Fire Department Standing Water Operations
Ross Valley Fire Department Swift Water Operations
Ross Valley Fire Department Standing Water Operations Binder

612a. Flood Threat Recognition Systems

(75 pts)
San Anselmo has a manual Flood Threat Recognition System (FTR). Personnel follow the actions listed in the Emergency Procedures, based upon heights of the creek flood gauge.
The Creek Flood Gauge is located at the Bridge Street bridge and monitors the level of San Anselmo Creek. This is the location where the creek historically will overflow first in San Anselmo. Thirteen feet is the creek level at the bottom of the building at 730 San Anselmo Avenue. The Flood Gauge is creates a digital graph which can be viewed online .
Our Flood Control District at Marin County Public Works uses to track the County flood control gages. The website provides maps, graphs, data downloads.
Link: Marin Onerain

Flood Control personnel act as liaison between the weather service (who provides weather predictions), the Office of Emergency Services (who facilitates County-wide emergency procedures), and the Road Crews (who are out in the storm and providing hands-on information as well as on-the-spot maintenance). The rain gages are used to develop the design storms that go into the hydraulic models for the various flood studies and maps. Gages record rainfall automatically and send it via ALERT system to One Rain where it goes on the web. Flood Control staff watch the gage values and take action when the intensity reaches greater than 0.5 inches per hour. This information is feed manually into flash flood warnings. Before and during a predicted storm staff monitors the gages 27/7, command center style, to issue warnings.

612b. Emergency Warning Dissemination

(75 pts)
The Town prepares and distributes event-specific fliers as needed with information about anticipated events such as heavy storms and potential flooding.

The Town has a flood horn located in the Town Hall tower. The horn is audible from areas subject to flooding. The horn is sounded when flooding is imminent. Town staff will sound the horn with 5 blasts, a pause, 5 blasts, a pause and 5 blasts. San Anselmo’s flood horn is tested every Friday at 12:00

EWD1- Tens and MEANS are two forms of telephone alert systems with prescripted messages.
Link: San Anselmo Tens and MEANS web page

MEANS, the Marin Emergency Automated Notification System, is an automated telephone notification system that makes phone calls automatically through a database built by the Town. It is used to deliver pre-recorded messages to businesses in specific areas of town depending on the nature of the emergency. It is also used to deliver pre-recorded messages to your cell phone or VOIP phone.

If you are a merchant, you can add or change a MEANS and/or emergency contact phone number by updating your emergency contact information with the Department. You can download a new form online.

If you are a Town resident who does not have a landline telephone send us an email with the word MEANS in the subject line. Include your name, address and the phone number you wish receive emergency notification messages. You will receive an email reply letting you know that the information has been entered in the MEANS database.

TENS (Telephone Emergency Notification System) is an automated telephone notification system that works automatically through the 911 Emergency Telephone database. It is used to deliver pre-recorded messages to residences or businesses in specific areas depending on the nature of the emergency. You do NOT need to sign up for this notification system. If you do not have a landline telephone at your home or place of business, then you should sign up for MEANS.

EWD2- The size of the watershed and individual nature of the storms prevents good estimates of flood heights with much advance notice. No credit requested.

EWD3- Sounding of the flood horn is fixed at 13 feet, other responses are initiated at 6.5, 8.14, and 11.14 feet.

EWD4- Door-to-door public addressing. No credit requested.

EWD5- The Emergency Procedures call out an EOC (Emergency On-Call) Chief, who then calls out EOC staff and activates the Emergency Alert System at fixed creek heights.

EWD6- The Emergency Procedures state that when the creek reaches 11.14 feet, activate MEANS phone call to merchants and activate TENS phone call to flood prone areas, plus MEANS notification to local officials.

EWD7- Cable Television Overrides. No credit requested.

EWD8- Other systems; nixle is a trusted, real-time, community based text / email / web browser information service that you can choose to receive at no cost on your smart phone or computer. You MUST register to use it. You can choose what type of information you receive and whether it comes to you by text message, email or via your web browser. The Police Department posts public safety alerts, traffic bulletins and community information on nixle.
Link: Central Marin Nixle web page
Radio 1610 AM is the Town’s local public information and emergency radio information station. During emergencies Town staff will broadcast timely information on Radio 1610 including weather and storm warning and watches, street closures, and suggested evacuation routes.

The Town website has an Emergency Alert icon on the left hand side of its home page. If the icon is flashing red, then the Emergency Alert system has been activated. Clicking on the icon will direct you to information regarding the current emergency.
Link: San Anselmo Homepage

Central Marin Police use the social network 'Nextdoor' to communicate Emergency Warnings.
Link: Central Marin Police website with link to Nextdoor
Link: Example Nextdoor screenshot

Town administration staff also post emergency storm information to the Town facebook and twitter accounts.

Marin County has an emergency preparedness program called Ready Marin, which provides 'Get Ready' and Community Emergency Response Team (CERT) training.
Link: Ready Marin

EWD9- San Anselmo Town Hall, which is the Emergency Operation Center, is equipped with a NOAA weather radio, although it is unknown if other community facilities have them.

EWD10- Flood inundation maps from five different recurrence intervals are posted online. They were developed for, and are hosted by, the regional flood control district and are linked on this page of San Anselmo’s website
Links: San Anselmo Flood Map Information
5 year recurrence interval
10 year recurrence interval
25 year recurrence interval
50 year recurrence interval
100 year recurrence interval

612c. Flood Response Operations

(115 pts)
Operations are called out in the Emergency Flood Procedures table described in section 610, including specific actions tied to creek levels.
Attachment: San Anselmo Emergency Flood Procedures

612d. Critical Facilities Planning
San Anselmo’s critical facilities are called out in the Emergency Procedures. Flood Gates are staged at 8.14 feet, these protect Town Hall, police, and the Emergency Operations Center.

612e Marin County OES is a certified StormReady and TsunamiReady community. San Anselmo is working on becoming certified, but partial credit is requested as a municipality within Marin OES jurisdiction.

620 Levees

No credit requested- No levees exist in San Anselmo

630 Dams

(160 pts)
Marin Municipal Water District owns and operates a series reservoirs. A small portion of San Anselmo is within the mapped dam inundation zone below Phoenix Lake. This reservoir is currently being retrofitted for flood control storage, thus its capacity will be increased during flood events. San Anselmo requests California Uniform Credits for state regulatory protection activities.