What Are Urban Growth Boundaries and Why Do We Need Them?

Our goal at Greenbelt Alliance is to conserve the Bay Area’s natural and agricultural landscapes while promoting climate-smart urban development that creates healthier, wild-fire safe, diverse, and affordable communities. One of the most important policy tools that city planners can use to achieve this goal is the urban growth boundary.

What Is An Urban Growth Boundary?

An urban growth boundary (UGB) separates urban areas from the surrounding natural and agricultural lands, or greenbelts. It puts a limit on how far out the city can expand. UGBs are often voter-approved and set for a specified period of time, like 20 years. Different cities may call these boundaries by different names, such as “urban limit lines” or simply “growth boundaries,” but they serve the same purpose of stopping sprawl development and encouraging sustainable growth practices. Greenbelt Alliance led the fight to create the Bay Area’s first urban growth boundaries in 1996 and has been their champion ever since.

Why Do We Need Them?

As we decide how to face climate change, extreme weather and a housing crunch, we need to double down on climate-smart growth near jobs and transit and the protection of natural land and water. The urban growth boundary is a proven and critical tool for doing so.

Urban Growth Boundaries accomplish two goals:

  1. Safeguarding greenbelts from sprawl development.
  2. Encouraging climate-smart growth which creates more mixed-use, walkable, affordable, and thriving neighborhoods within urban limits.

Compact cities and towns, rather than sprawling development, tend to be less dependent on cars, which is good for the environment as well as the community’s health. It’s easier for residents to walk, bike, or take public transportation, which reduces the city’s carbon footprint while also encouraging exercise and decreasing harmful air pollution. Additionally, a higher-density city uses less water.

Climate Healthy Urban Growth Boundaries

The climate and environmental benefits of urban growth boundaries are clear. By focusing growth inside existing towns and cities, a UGB reduces driving and greenhouse gas emissions; saves money on water, sewer, parks, and roads; protects the environment; reduces wildfire risk; and allows for many types of housing across the income spectrum. And it costs taxpayers nothing.

Cities and towns with distinct boundaries and thriving downtowns, rather than sprawling development, tend to be less dependent on cars, which is good for the climate by reducing tailpipe emissions as well as the community’s health. It’s easier for residents to walk, bike, or take public transit, while also encouraging exercise and decreasing harmful air pollution. A well planned city also uses less water and energy.

UGBs and Wildfire Safety

We’ve seen firsthand during recent wildfires that communities with defined urban boundaries surrounded by greenbelts and farmland are safer and easier to defend than those sprawled out into the forests and wildlands. Firefighters were able to hold back walls of flames on the well defined edges of Windsor and Healdsburg with UGBs by staging fire response teams and equipment in the surrounding parks, open space and agriculture.  While there are certainly exceptions, such as Coffey Park in Santa Rosa, research shows that more compact communities are far more wildfire safe overall.

This may seem obvious but we now have the science that confirms it. Researcher Alexandra Syphard of the Conservation Biology Institute has published extensive research on risk to life and property from wildfire. She found over and over again that lowest wildfire risk is in the urban areas. The highest wildfire risk is in medium densities, which are often seen in the wildland-urban interface—areas where homes are built near or among lands prone to wildland fire. Upholding UGBs makes a difference

Urban Growth Boundaries Are Not the Cause of the Housing Crisis

Some people may argue that urban growth boundaries make the affordable housing crisis worse. Higher-density development, however, is actually less expensive than sprawl development. For example, providing transportation and public services is much less costly in a compact city than in a spread out one. Compact development also supports the local economy by improving accessibility to local businesses. Download our urban growth boundary fact sheet to learn more (PDF).

Put simply, an urban growth boundary determines where we build, not what we build. UGBs have not caused the housing crunch. The rest of the Bay Area demonstrates that sprawl does not provide affordability.

The requirements for affordable housing are decided by local elected officials and city staff based on General Plans and zoning code requirements. The current housing crisis across the nation has resulted due to multiple factors over decades including loss of state and federal funding, stagnant wages for most workers, and the high costs of labor and materials. There is no simple fix, but building inside urban growth boundaries offers a climate-smart solution.

Urban Growth Boundaries in the Bay Area and Beyond

The State of California is certainly on our side when it comes to growth boundaries. The governor and legislature are pushing for climate-smart growth across the state with more funding for affordable homes and mandates to develop neighborhoods close to transit, jobs and schools. Sprawl development into greenbelts is nowhere in the policy mix, yet in many places it continues to spread. That’s why local activists are gearing up to defend UGBs city-by-city and county-by-county and gathering signatures to put new UGBs before the voters.

City and County Urban Growth Boundaries in the Bay Area, include:

Alameda County: Alameda County, Dublin, Fremont, Hayward, Livermore, Pleasanton

Contra Costa County: Antioch, Contra Costa County, Danville, El Cerrito, Hercules, Martinez, Oakley, Orinda, Pinole, Pittsburg, Pleasant Hill, Richmond, San Pablo, San Ramon, Walnut Creek

Marin County: Marin County, Novato

Napa County: American Canyon, Napa, St. Helena, Yountville

San Mateo County: San Mateo County

Santa Clara County: Cupertino, Gilroy, Los Gatos, Milpitas, Morgan Hill, Palo Alto, San Jose

Solano County: Benicia, Fairfield, Rio Vista, Vallejo, Vacaville

Sonoma County: Cloverdale, Cotati, Healdsburg, Petaluma, Rohnert Park, Santa Rosa, Sebastopol, Sonoma, Windsor

See where we’re currently working to establish, uphold, and improve the Bay Area’s UGBs. 

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