Eight Important Questions City Officials Should Ask About Flood Control in Their City
Yvonne Hunter is a legislative representative for the League. Numerous individuals from the public, private and nonprofit sectors also contributed to this article, and their assistance was invaluable.
In the aftermath of the horrific floods and devastating damage in New Orleans and other Gulf Coast cities last year, California is taking a hard look at its own flood management infrastructure and laws. This articlepresents questions city officials should ask about flood issues in their city so they can make informed decisions and be prepared in the event of a flood. These questions are a starting point for discussion and should not be considered all-inclusive or complete.
- Is a 100-year flood one that happens once every 100 years? No, a 100-year flood is not a flood that occurs only once every 100 years and thus can be ignored today. Actually, the designation really means a 1 percent chance of flooding in any given year. This translates into a 26 percent chance of flooding over the life of a typical 30-year mortgage. “Yikes” is often the response to this definition.
- Is your city in a 100-year flood zone? This is one of
the most basic items of information needed to make informed
decisions about flood management in your city. The Federal
Emergency Management Agency’s (FEMA) Flood Insurance Rate Maps,
which show the 100-year floodplain, are the most commonly used
maps to identify flood risk. FEMA uses these maps to determine
whether flood insurance is required for federally backed
mortgages. However, many FEMA maps are outdated and do not
reflect the current hydrology and flood risk. They may not
identify all flooding or reflect the impacts of recent
floods, increases in rainfall data, changes in hydrology due
to development, or erosion or damage to levees. Some FEMA
maps are available that identify 200-year and/or 500-year
floodplains, as well.
When asking whether your city is in a 100-year flood zone, be sure to inquire whether the information that the answer is based on is current. Sometimes the response to this question is, “No, we’re no longer in the 100-year floodplain” or “We have been mapped out of the 100-year floodplain.” This often is interpreted to mean we don’t need to worry. Ask again for more details.
Portions of a city might be mapped out of the 100-year floodplain because the local or regional flood control agency has built dams, detention basins or drainage infrastructure, or strengthened levees in a way that removes the land from the 100-year floodplain. Or a portion of a city may also be removed from the 100-year floodplain because the city has adopted construction and site design standards to mitigate the flood impacts (such as requiring new buildings to be elevated one foot above the base flood elevation) or because the levee meets a 100- or 200-year standard. But if the levee fails in five years due to poor maintenance or if there is a greater than 100-year flood, your city will experience flooding regardless of whether it is outside the 100-year floodplain. So the lesson is to understand the nuances of the answers to your questions and consider asking more questions and planning accordingly.
- If your city has a flood risk, what is its cause? Is potential flooding in your city from a levee break, an overflowing stream or creek, runoff from an alluvial fan, a coastal storm, dam break or a combination of causes? It’s important to know how, where, how deeply and why your city may flood so you can be proactive, plan accordingly and be prepared.
- If your city is behind a levee, how recently has it been
evaluated for reliability? Often you will hear the phrase, “The
city is protected by a levee.” Ask what is meant by
“protected.” Does it mean the levee is suitable to actually
protect the city? Or does it really mean “The city
is behind a levee”? Because if the condition of the
levee is not suitable for urban development, then your city is
not really protected.
In areas where urban development has not occurred, very frequently the levees are so-called “ag” levees, designed to protect farmland from flooding. They were not designed for urban development. Before making any decision about new development behind a levee, it is absolutely crucial to know the condition of the levee and to require upgrades if necessary before approving development. While FEMA requires 100-year protection before flood insurance is not required, some communities require either 200-year protection before approving development or are working toward 200-year protection after achieving the 100-year standard.
Some levees already have been certified by the Army Corps of Engineers as providing 100-year or 200-year protection. It’s important to ask when the certification was done. A certification performed in 1986 or even 1990 might not be adequate if the area has experienced flood events, development has occurred upstream or seepage under the levee has reduced its actual level of protection. Ask if it is a “grandfathered” levee that was accepted by California from the federal government. Grandfathered levees are generally assumed to have 100-year protection, even though they really may have far less protection.
Finally, remember that even if your city is behind a levee with a current certification of 100- or 200-year protection, it could experience a 150-year or 250-year flood and thus be significantly impacted. Being informed will help your city to be better prepared.
- Do you know how deep the water will be if your city floods? Despite the best planning, floods happen. If your city floods, do you know where and how deep the water will be? Will the water be less than a foot deep if a creek or storm drain overflows? If a levee breaks, will flooding be three, 10 or 20 feet deep?Obviously, the location and depth of flooding will have a significant impact on your emergency response needs, the damage to life, property and the economy of your community, and your city’s ability to re- cover. Knowing the community profile of a potential flood can also help you plan to avoid building in areas with a potential for deep flooding and develop your mitigation measures accordingly.
- Who manages the flood control infrastructure that protects your city? Is your city the primary flood control agency? Or is it a special district or the county? For example, many cities are served by special flood control agencies that provide countywide flood management services. Similarly, the majority of levees are owned and operated by local reclamation or levee districts, not the city that is behind the levee. It’s important to have a good working relationship with those agencies and to ask about their flood management or levee operation and maintenance program, and emergency response capabilities. For example, ask whether the flood control agency is prepared to vigorously respond to a flood if a levee threatens to fail or a stream or river overflows. Ask if they have backup contracts for emergency flood work and if they have emergency supplies stored in strategic locations.
- Is your city prepared for a flood emergency? Do you have the
resources available for a flood disaster? Are there plans
in place to inform the public of a potential
flood emergency and evacuate people out of the flood
inundation area? Is the city proactive in educating people about
the importance of being prepared so they can take individual
responsibility, including providing information to
non-English-speaking residents, low-income citizens and
tourists? Do you have equipment and personnel ready to roll
during storms or high water? Is the city prepared to provide
sandbags to residents?
Does your city have an advance notification system? What about the ability to evacuate frail, elderly and disabled residents? Is your city working with the business community and the school district in this regard? Does the city provide training for city employees and does it coordinate with other agencies and nonprofit organizations? Do you coordinate with other emergency response or flood management agencies?
- Does your city follow good planning practices? Does your city have an up-to-date floodplain management ordinance (required by FEMA if your city is in a 100-year floodplain and you want your residents to be eligible for low-cost federal flood insurance)? Do you have policies to review the design of new developments so as to avoid, minimize or mitigate the potential flood impacts? Has your city considered site design criteria for new developments that reduce runoff and increase absorption of water, such as those in the Ahwahnee Water Principles for Resource-Efficient Land Use (see page 16)? Are critical facilities such as hospitals, schools, fire and police stations, and corporation yards located outside the deep flood areas, if possible?
Good projects that are able to withstand flooding to the maximum extent possible don’t just happen. They are the direct result of thoughtful elected officials, city planners and public works officials asking the right questions at the beginning of a project and continuing the dialogue with the developer and community throughout the project to make it happen.
Remember, the questions in this article are a starting, not ending, point. We en-courage you to use them to help you and your colleagues become better educated so that your community can make in-formed decisions. If your city floods in the future and your constituents want to know if you asked the right questions, will you be able to say, “Yes, I did”?