Planner Speak: What is a flood plain exactly?

When the roads get wet and slippery I know that my car can hydroplane. Can it flood plain too? What is a flood plain exactly?

A flood plain (n.) is the area next to a stream or river that may be covered with water during a flood.

The Federal Emergency Management Agency (FEMA) maps flood plains based on the risk and type of flooding. One line that FEMA draws is the boundary of the 100-year flood zone. Every year there is a 1% chance that flood waters could reach or pass the boundary line of the 100-year flood zone. Don’t let the name mislead you. It is possible for a lot of the land within the 100-year flood zone to flood on a fairly regular basis, far more often than once every hundred years. FEMA considers these lands to be Special Flood Hazard Areas, with a high risk of flooding.

FEMA also maps the boundary line of the 500-year flood zone. Similarly, every year there is a .2% chance that flood waters could reach or pass this boundary line. FEMA considers these lands to have a moderate risk of flooding.


The interactive map below shows the 100-year and 500-year flood zones in Hamilton County as well as the floodways. The floodway is the channel of a river or stream as well as the land next to the channel that has to stay open to carry the deeper, faster moving water during a flood. In the map below, the floodway is blue, the 100-year flood zone is red, and the 500-year flood zone is pink.

Flood plains protect the health and quality of our rivers, lakes, and streams and the water that comes through our faucets. They help to control the flow of water and can absorb pollutants and sediments, such as gravel and clay, before they drain into streams and rivers. Flood plains are home to many types of plants and wildlife, including threatened and endangered species. It is important for communities to protect our flood plains both to keep our rivers, lakes, and streams healthy and to keep our homes and businesses from being damaged by floods.

Planner Speak: What do you mean by zoning?

You’ve probably gotten “in the zone” while doing something you enjoy, be that baking a cake, playing an instrument or going for a long run, but what do planners mean when they talk about zoning?

Zoning (n.) categorizes properties in a city or county into different classifications called zones.  Each zone has a set of rules about features of development such as the land use, height of buildings, amount of parking, and density. In the past, zoning has been more concerned with the land uses allowed in each zone than the form of development. As a result, common zoning categories are often residential, commercial, office, manufacturing, warehousing, and agricultural.

You might have heard about zoning in the news when a property owner needed a change of zoning for a development project. To learn more about the rezoning process, check out the Development Services page on the RPA website.

Why do we use zoning? Originally, zoning was created to prevent conflicts between different types of land uses. For example, zoning can be used to keep a large factory, which might produce loud noises and odors, from being built right next to homes.

A zoning ordinance has two major parts: text and a map, or several maps. The text explains the rules for each zone. The map applies the zones to sections of land. Unincorporated Hamilton County and each town and city in the county have their own zoning ordinance. Here are links to the text sections of the zoning ordinances. Here is a zoning map for Hamilton County. Do you know what the zoning is for the property you live on? To find out, click the house icon in the toolbar in the top center of the screen and type in your address. Then, click on the RPA icon to the right of that and click on your property.


Below is a map of the zoning in the MLK Neighborhood of Chattanooga. Properties are color coded according to their zone, and the letters followed by numbers are abbreviations for different zones. For example, the light yellow properties are in the R-1 Residential Zone, the red properties are in the C-3 Central Business Zone, and the bright purple properties are in the M-2 Light Industrial Zone.


Traditional zoning, or zoning that is more concerned with the land uses allowed in each zone than the form of development, is the type of zoning that we see in Hamilton County and the towns and cities in the county. Traditional zoning usually does a good job of preventing conflicts between land uses. However, because it separates land uses, it often means that jobs, shops, and homes are separated from each other. The distances between different types of land uses mean that most people in our county have to drive to get to the places they want to go on a daily basis.

Through our ‘What do you want to grow?‘ game, we learned that two of the public’s top priorities are “neighborhoods with jobs, shops, and grocers” and “transportation options”. Many cities are turning to more innovative types of zoning, such as form-based codes, for neighborhoods that want to have jobs, shops, and homes close together, where it is possible to walk, bike, or take transit to get to the places you go on a daily basis. Form-based codes focus more on how buildings are designed and how they fit in with their surroundings than on the land use. Form-based codes still have rules about land use, but there is more focus on how buildings fit in with the network of streets, public spaces, and other buildings around them.

In the ‘Growing Forward’ planning framework, we will update our codes and policies in step three, ‘Building the Future’. Creating form-based codes for certain districts and neighborhoods may be a part of the code update. In fact, last Tuesday the Chattanooga City Council discussed a demonstration project that would create form-based codes for five different areas in Chattanooga. One of the reasons for updating our codes is to make sure they help us fulfill the vision that we set in step one, ‘Renewing Our Vision’ and step two, ‘Strategy For Great Places’. Now is the time to get involved to help us build a stronger and more vital place to live, work, and play. Keep an eye on our event calendar for upcoming meetings. At these meetings, you will have the chance to review and make suggestions about our goals, the very goals that we will use to guide changes to our codes and policies.

Where’s Tim Now?

Last week Tim was at Tennessee Riverplace, across the Tennessee River from William’s Island. The island is 450 acres and over 2 miles long. The island is owned by the State of Tennessee Division of Archaeology and managed by the Tennessee River Gorge Trust. Although no one lives on the island now, archaeologists have found evidence of human settlements on the island dating back to as early as 12,000 B.C.

Williams Island from TN Riverplace-jt_answer


What do you want to grow? – The results are in!

The results are in! Over 500 people played our “What do you want to grow?” game last month. They participated through an online survey or they visited us at one of dozens of “Pop-up Planners” throughout Hamilton County in May. Below is a map of the locations and types of events recently held! Map of Locations What do you want to grow? The RPA traveled throughout the county to ask you, the public, to prioritizes how we grow and develop as a county and the cities within. We identified 14 priorities that came up over and over again for plans that have been written for our area. We wanted to know which you think should be our top priorities. We encourage you to take a look below at what we heard. Here is how you ranked these 14 priorities.

Prioritiy list

Hamilton County is filled with different people with varying needs. How do these priorities change across the County? Below is a series of maps that show you the top priority within each zip code across Hamilton County. Click the map to see a full screen image.

The top priority per zip code.

Map of priorities

Second Priority per zip code.

Map of priorities -second priority

Third priority per zip code.

Map of priorities -third priority


Do we have different priorities based on our age? See the graph below to learn what the top three priorities were for Hamilton County residents in each age bracket.

top-priorities by age


Do we have different priorities based on our income? The graph below shows the top three priorities for Hamilton County residents in each household income bracket.

top-priorities by income

We asked you, the public, if you wanted the government to make a policy to enforce or promote any of these priorities. Below is the list of priorities and how important to people new policy or regulation is in protecting them.

 which priority regulation

In addition to asking people to prioritize the top 14 issues that seemed to come up over and over again in plans for our area, we gave them the opportunity to write in issues that we missed. During our travels throughout Hamilton County we heard from hundreds of residents about very specific issues, but there were several write-in priorities that showed up over and over again. Some, like education, , for which our agency has limit responsibility doesn’t preclude us from sharing with you and other agencies that the issue was heard. Below is a listing of repeated comments and write-in priorities we heard.

– Concerns about the safety of neighborhoods
– Concerns about gang violence
– Concerns about poor lighting and dark streets

– Concerns about older schools failing while money goes to building newer schools
– Concerns about quality of facilities and educators
– Concerns about enough places for continuing and adult education

Marginalized Population
– Concerns about residents being able to stay in their homes as they age
– Concerns about physical access for those with disabilities

– Concerns about raising taxes to pay for new infrastructure
– Concerns about raising taxes to pay for existing infrastructure not capable of paying for itself

What happens next? We use the input from the public along with our analysis of local and regional trends, understanding of planning principles, and feedback from local government officials to form recommendations to the elected and appointed officials on plan goals and prioritization before the document is drafted.

Download raw results data here and data dictionary here

Download results as pdf here


Planner Speak: What exactly is economic development?

You’ve probably heard about decisions that were made, policies that were adopted, money that was spent, of land that was purchased in hopes of spurring economic development, but what exactly is economic development?

Economic development (n.) is actions that communities take to improve the economy and people’s well-being. Economic development can involve:

  • supporting existing businesses;
  • helping new businesses get started;
  • training or recruiting people for jobs;
  • making sure spaces are available for new businesses; and
  • making sure infrastructure that businesses need is in place.


PopUp          ChattState


One part of Chattanooga’s infrastructure that community leaders hope will support new businesses and jobs is gigabit-per-second internet. Chattanooga Mayor Andy Berke has put forward the idea of creating an “innovation district” to build upon the fast, cheap internet service. The district would bring companies that develop technology and conduct research to a central location where they can work together and have easy access to housing and services like restaurants.

Why do communities get involved with economic development? Some of the goals include keeping jobs in the area, bringing more jobs to the area, bringing in more tax money, keeping the economy stable, increasing the amount of products and services the community is able to produce for itself and sell to other areas,  keeping money in the community, and reducing poverty. 

Who is responsible for economic development? Quite often governments, non-profit organizations, and private companies work together on economic development projects. The redevelopment of Downtown Chattanooga and the riverfront is a good example of public-private partnership. The government, non-profits, and private companies worked together to plan, pay for, and build the development that we see today, including the Tennessee Riverpark, the Tennesse Aquarium, and the many hotels and businesses.


To learn more about some of the agencies and organizations that are working on economic development for our area, check out the links below: