Floodplains and Flooding

What Are The Benefits Of A Floodplain?

Floodplains on Cape Cod provide many ecosystem services. They provide habitat for many riparian species, they can slow down the speed of an oncoming flood, they absorb floodwaters and reduce flood risk for the land behind them, reduce pollutants and improve water quality, and provide public access to the waterfront. Floods are part of a natural cycle and are even necessary to maintain the health of different habitats and species.

When they are developed, many of these benefits are diminished and the structures are at a high risk of flooding. Therefore, it is important to keep floodplains as open space wherever possible to maximize their natural benefits and minimize risk of damage to structures.

Floodplains and other sensitive areas are protected by the Clean Water Act. In Massachusetts, this is implemented through the Wetlands Protection Act regulations. Each town must adopt the state’s standards, but may have stricter requirements. All development in sensitive areas must be approved by the local Conservation Commission, and in some areas development may be prohibited in order to protect the natural functions of that land. A map of wetlands and other sensitive areas can be found by viewing the MassDEP Wetlands layers through the Coastal Zone Management Program’s MORIS online mapping tool.

What causes a flood?

A flood can occur anywhere on Cape Cod as a result of heavy rainfall, clogged drainage systems, snow melt, and storm surge from the Atlantic Ocean, Cape Cod Bay, and Nantucket Sound associated with tropical storms, nor’easters, and more increasingly, heavy rainfall events. Properties all over Barnstable County are susceptible to floods, even if they are far from the water’s edge. Those properties closest to the coast are most susceptible to deep flooding, but coastal floodplains can extend far inland.

The coast is uniquely susceptible to flooding. It is affected not only by rain or by rivers overflowing their banks, but by the rapid rise in ocean waters known as storm surge that accompanies tropical storms and nor’easters. This storm surge can be very high (for example, the storm surge at the Battery in New York City during hurricane Sandy was 14 feet above the average water height) and comes with strong waves. Storm surge and the accompanying waves are extremely powerful: one cubic yard of water weighs approximately 1,700 pounds.[1] When the force of strong, wind-driven waves are added to that weight, the damage can be devastating. Added to this weight may be debris from other structures that have already been damaged, which then become battering rams to neighbors. Structures in the way of a storm surge are likely to suffer damage if not properly constructed.

Not only is an influx of water damaging, but water left standing after a storm can be deadly as well. Standing floodwaters can contain many contaminants. When there is excessive rain, municipal wastewater systems get overloaded and raw sewage can consequently overflow. Litter from roads, yard debris, and lawn chemicals are picked up by floodwaters and stay suspended in standing water. If electricity has not been cut off, there is a high risk of electrocution in standing floodwaters from fallen wires. Fires are also common when gas lines are broken by debris or the force of the flood. Even after the flood has receded, soaked items can hold onto sediment and contaminants and generate dangerous mold.

Visit the Flood Maps page to find out if your property is likely to experience a flood.

Historic Flooding

In 2016, AmeriCorps Cape Cod and Cape Cod Cooperative Extension undertook a project to document high water marks across Cape Cod. This project placed signs in four towns (Mashpee, Barnstable, Yarmouth, and Provincetown) indicating high water levels from Hurricane Bob, the Blizzard of 1978, and Base Flood Elevations (the expected height of flooding from a flood map). Data came from US Army Corps of Engineers records. See below for a map of these high water mark locations, including elevations and additional information for each location (click on each location to see additional information). 

Why should I worry about floods and flood damage?

The costs of suffering flood damage are high. There are bodily hazards to humans, such as risk of drowning, infection from bacteria in the water caused by raw sewage, road debris, and household chemicals, and respiratory and allergy issues associated with mold. For structural damage, this flood damage estimator  provides a good overview of damage and costs that can come with various levels of flooding.

A common misconception is that flood damage will be covered by a homeowners insurance policy. However, standard homeowners insurance does NOT cover flood damage. If a property is located in a floodplain and has a federally-backed mortgage, the property owner is required to purchase flood insurance for that property. In order to insure a structure against flood damage, a separate policy must be purchased from a private company or the more affordable National Flood Insurance Program. For more information, visit our National Flood Insurance Program page.

How can I protect my home from flooding?

To protect against floods, it is important to build homes and businesses in a way that reduces flood risk. When towns issue building permits they review both the location of the proposed structure for its likelihood of flooding as well as how the structure will be built and what materials will be used. If the property is located in a Special Flood Hazard Area, shown as Zones A and V on a flood map, it has a 26% chance of flooding over the course of a 30-year mortgage. Because of this high flood risk, structures built in these areas are subject to strict building standards to ensure structures are reasonably protected from flood damage.

Building codes are a minimum starting point. As a property owner you are allowed to build your home or business to higher standards to ensure the safety of your structure. If you are interested in retrofitting your existing home or business rather than building new, there are also actions that you can take to further protect the structure from flood damage. Examples of these actions include elevating the structure well above the expected flood level, installing flood vents (and keeping them free from obstructions), elevating utilities such as your furnace, washer and dryer, and HVAC unit above expected flood levels, and filling in a basement. There are also some floodproofing options, but if they fail they come with a high risk of damage. Many of these actions will also reduce your flood insurance costs. You should also maintain drainage around your structure to ensure rain does not drain into your basement or crawl space (but also be sure it doesn’t affect your neighbor), and the town and Cape Cod Mosquito Control Project are responsible for maintaining public drainage pathways.

To protect your property against an imminent flood, you can use sandbags to keep smaller amounts of water out, move important contents and furniture to a higher level, and shut off your gas and electricity to reduce the risk of fire.

You can get more information on protecting your home by reviewing the Homeowner’s Handbook for Preparing for Coastal Hazards, FEMA’s Homeowners Guide to Retrofitting, or talking to your local building official. Note that all work in a floodplain needs to have a permit from the building department.

Finally, you should purchase a flood insurance policy to further protect your structure and possessions. Visit the National Flood Insurance Program page to find out more information about flood insurance.

How can I protect my family during a flood?

If a storm is coming and an evacuation is issued for where you live, it is important that you leave the area to protect yourself and your family from the many hazards brought by floods. If you ignore evacuation announcements, you may be putting yourself and your family at unnecessary risk. Storm surge often arrives quickly and can increase in depth in a matter of minutes. People are often caught off guard and find that they do not have enough time to escape the surge, and are forced into their attics or onto their roofs. Rescue efforts to get these people back to dry land endanger the lives of the rescuers and are costly to taxpayers. Visit the State’s Hurricane Evacuation Zones page to see if you live in a likely evacuation zone.

If you come across a flooded road, you should not drive across it unless the water is moving slowly and less than knee-deep. If your car stalls, you should get out and get to higher ground – floodwaters can rise quickly and sweep away cars and people.

In the event of any disaster, you should create an emergency kit and plan. If your family gets separated, there should be a designated family member or friend to call who is outside of the disaster area. Emergency kits should include enough food and water for each person in your family for three days, as well as first aid supplies, any required medications, flashlights, and batteries. Bring important documents with you as well, such as birth certificates, social security cards, credit cards, and insurance policies in case you cannot return to your home for an extended period of time. Find out the location of the nearest shelter.

Click here to see a regional shelter map for Cape Cod.

If you have pets, be sure to include them in your plan – ensure they have enough food and other necessary supplies. If you need to go to a shelter, check your pet in with the Cape Cod Disaster Animal Response Team before checking into the shelter yourself. Your pet will be in the same building with you, but you will only be able to visit with them during visitor hours.

For more information on preparing for a flood or other natural disaster, visit the Barnstable County Regional Emergency Planning Committee.

To see up-to-date information on current and predicted water levels, visit the webpages for our local tide gauges:

What should I do after a flood?

If your home or business has been damaged, be sure to acquire all building permits from your local building department before you rebuild anything. If your structure was damaged more than 50% of the market value, or you plan on renovating the structure more than 50% of the market value, you will be required to bring the structure up to code. In flood zones, this may mean elevating the structure, installing floods vents, elevating utilities, or other actions.

If your home or business has sustained damage, you should shut off the electricity and gas before entering. Wait until the water recedes to go inside your structure. Be aware of any major structural problems, such as foundation cracks, sagging porches, or sagging ceilings. Once you can safely enter the structure, air it out and remove mud, dirt, and sand to reduce the risk of mold and contamination. For more information, visit FEMA’s website and see this guide from the Red Cross.

[1] National Weather Service/National Hurricane Center. 2014. “Storm Surge Overview”. http://www.nhc.noaa.gov/surge/

National Flood Insurance Program

The National Flood Insurance Program (NFIP) is operated by the Federal Emergency Management Agency (FEMA). It was created by Congress in 1968 to provide affordable flood insurance to property owners and reduce federal expenditures on post-flood disaster cleanup costs. In theory, the availability of low-cost flood insurance would allow private property owners to cover their own risk of flooding and alleviate the cost to the federal government.

NFIP Basics

Flood insurance is available through the NFIP for homeowners, business owners, and renters. For residential properties, coverage is available for up to $250,000 on the structure and $100,000 on contents. For commercial properties, coverage is available for up to $500,000 on the structure and $500,000 for contents. Click here to see a fact sheet from FEMA on what is and is not covered with a policy from the NFIP.

Flood insurance rates are determined by a combination of flood risk as determined by a Flood Insurance Rate Map (see below for more information on flood maps), type of foundation, and comparing the expected elevation of flooding to the first floor of the structure. For information on how to lower flood insurance costs, visit Floodsmart.gov.

For new policies, there is a 30-day waiting period for a policy from the NFIP to become effective.

Flood insurance is required for any building with a federally-backed mortgage (most mortgages fall into this category) that is located in the floodplain, which can be identified as zones A and V on a Flood Insurance Rate Map.

Flood insurance from the NFIP can be obtained through many local insurance agents, and all Cape Cod towns are eligible for NFIP flood insurance. For more information on obtaining flood insurance, visit Floodsmart.gov.

Flood Insurance Reforms

Beginning in 2012, the NFIP underwent a series of reforms to ensure that the program remains financially sustainable. After Hurricane Katrina, the program was $18 billion in debt. After Sandy, that number rose to $24 billion. This debt is the result of the devastation caused by large storms, combined with the format of the program. Any structure that was built before the first Flood Insurance Rate Map became effective in the community where it is located was has historically paid a subsidized rate that is, very generally, about 50% of the true cost based on risk. These structures are typically high-risk, frequent-claim structures that cost the NFIP significantly more money to insure than these structures pay in premiums. In order to get the program out of debt and ensure that property owners understand their risk, Congress opted to gradually remove these long-standing subsidies so that all property owners pay full rates.

These reforms began to take effect in 2015. The increases that year will likely be the most significant, as they included rate increases and new fees. Moving forward, the fees should remain the same while rates continue to increase. Subsidies will be phased out for second homes and businesses at a rate of a 25% premium increase per year until full risk-based rates are reached. In 2017, all other properties will experience an average 6% increase on their flood insurance premiums. The average increase is likely to change every year.

In response to these rising costs, many municipalities are interested in joining the Community Rating System, which provides flood insurance discounts to policyholders within participating towns. Towns take on activities and regulations that are designed to reduce flood risk and improve public safety in exchange for these discounts. For more on the Community Rating System, click here.

Tips for National Flood Insurance Program Policyholders

  • You have likely received a letter from FEMA telling you more information about the flood risk for your property. Many properties are charged a rate for flood insurance that is not based on the flood risk to that property, resulting in a lower flood insurance cost. As part of the recent flood insurance reforms, those rates are increasing. The letters from FEMA inform policyholders of their true risk and the associated cost increases, and how you may be able to reduce those costs. More information on these letters can be found on the FEMA website.
  • If your home is a primary residence (where you or your spouse live at least half the year), be sure to return the form you receive from your insurance company providing proof of primary residence. Without this information, you may be charged a rate based on a second home, which will be significantly higher than the rate for a primary home. Review your flood insurance bill summary to see whether your home is considered primary or non-primary.
  • Obtain an elevation certificate and send it to your insurance agent if your property is located in an A- or V-zone. This may result in a lower flood insurance rate, and will ensure that you are not charged more than you should be. Without this information, your flood insurance rate will be based on an average which may be higher than what you should pay.
  • Talk with your flood insurance agent or your town floodplain manager about structural mitigation possibilities. Mitigation actions such as elevating the structure on pilings, installing flood vents, or filling in the basement may help to lower flood insurance rates in many cases.
  • If your town participates in the Community Rating System, you will get a discount on your National Flood Insurance Program policy of 5% – 15%.  For more about the Community Rating System, visit our CRS page.

Flood Maps

Flood maps are used to determine whether flood insurance is required and what the cost will be, indicate where certain building and zoning codes must be enforced, and provide a general depiction of flood risk. Flood maps are created by the Federal Emergency Management Agency and provided for each town. All Cape Cod towns recently received new flood maps, which went into effect on July 16, 2014. To view these flood maps, visit the Map Service Center, enter your address, and choose to view or save the map.

Some towns may have more information available about flood maps. Many towns will read the flood map for you and tell you what flood zone you are in, as well as other relevant information. The links below are for towns with advanced mapping systems that may provide more information about flood risk or other factors affecting your property. Other towns may have GIS programs but may not have updated flood maps or may only have the links listed above.










If your home or business is located in the floodplain, shown as Zone A or V on a flood map, and you have a federally-backed mortgage (most mortgages are federally-backed), you are required to purchase flood insurance. The recent map changes meant that many properties newly mapped into the flood zone are now required to have flood insurance. See the National Flood Insurance Program page for more information about flood insurance and map changes.

Community Rating System (CRS)

The Community Rating System, or CRS, is a voluntary program that municipalities may choose to participate in to earn discounts on flood insurance for their constituents. Discounts range from 5% to 45%, with most Cape Cod towns able to earn a 5%, 10%, or 15% discount. This level of discount still requires a significant commitment from the town and is a great accomplishment.

In order to earn this discount, towns must undertake certain actions and regulations that reduce flood risk and improve public safety. Many towns are likely already pursuing several of these actions and can get credit for existing activities. Examples include enforcing building regulations, protecting open space, protecting wetlands, providing information about flood maps, conducting public outreach, and conducting stormwater management. Some activities undertaken by individuals can also earn credit, such as retrofitting a structure so that it is more flood-resistant, tearing down an older structure and replacing it with a new flood-resistant structure, and preserving open space in a floodprone area.

Currently, nine towns in Barnstable County participate in the CRS program:

  • Brewster (5% discount)
  • Chatham (10% discount)
  • Eastham (10% discount)
  • Harwich (15% discount)
  • Mashpee (10% discount)
  • Orleans (15% discount)
  • Provincetown (10% discount)
  • Sandwich (15% discount)
  • Wellfleet (10% discount)

Bourne, Falmouth, and Dennis are actively working on their applications with the assistance of the County-wide CRS Coordinator.

For more information on the CRS, visit the FEMA website.


Barnstable County/ Cape Cod Cooperative Extension’s CRS Coordinator

Barnstable County has a CRS Coordinator to help Cape Cod’s towns enter the CRS program and earn higher discounts. The CRS program is resource-intensive for towns because it is a complex program that requires significant familiarity to get the most out of it. Most local officials have several duties and do not have the time to become extensively familiar with the CRS and its requirements. The County-wide CRS Coordinator helps towns to apply to the CRS program, improve their ratings and earn higher discounts, and help maintain the activities to keep those discounts in the future.

This position is the first of its kind in the country. There is increasing interest in the CRS because of changing flood maps and rising flood insurance costs nationwide. With that increased interest there is an associated push to manage the CRS at a regional level to help alleviate the resource costs. Barnstable County is the first to implement a regional position and serves as a leader in this approach. The County program won the 2017 James Lee Witt Local Award for Excellence in Floodplain Management from the Association of State Floodplain Managers, and served as the inspiration for a CRS regional coordination bill in the pending 2017 National Flood Insurance Program reauthorization in Congress.


Shannon Hulst, Floodplain Specialist at 508-375-6952 or shannon.hulst@barnstablecounty.org

Greg Berman, Coastal Processes Specialist at 508-289-3046 or gberman@barnstablecounty.org