For years, communities along the Napa River have been devastated by flooding. Since 1862, twenty-two historic flood events have occurred in the Napa Valley. Over the span of 36 years (from 1961 to 1997), 19 floods caused over $542 million dollars in damage. Repeated flood damage in downtown Napa had eroded confidence in investors and business owners, washing away economic vitality and growth. The flood of 1986 was the most devastating in Napa’s history, damaging 2,500 residences and destroying 250 homes. 5,000 people were forced to evacuate the flood zone and 1,500 people were without work as a result of the flooding. The water was so high in parts of town that rescue boats left scrape marks on the roofs of submerged automobiles. A devastating and traumatic event, it set into motion a community movement to find a more natural solution to flood prevention.
Changes in the river and development in the valley had worsened conditions for flooding. Over time the Napa River became more channelized (deep and narrow), natural floodplains eroded away or were encroached upon by agriculture and urban development, and wetlands were drained and diked for farming. Natural features that managed storm flows had been lost and the river no longer had a way to accomodate large influxes of rainfall in the wet season. As a result, neighborhoods in St. Helena, Yountville, and Napa became prone to flooding. In the 60’s and 70’s, the US Army Corps of Engineers developed a preliminary flood control plan that proposed transforming the Napa River into a concrete channel with floodwalls and levees to keep flood waters out. Voters rejected the proposal by refusing to approve matching funds to set the project in motion. A community coalition was formed to find a more appealing solution to protecting the community and the river.
Friends of the Napa River (FONR) was founded in 1994 after a group of concerned citizens gathered in a living room to find a solution to flooding that didn’t involve destroying the natural features of the river. Specialists in the community came together and the Living River concept was born. Engineers, scientists, naturalists, business owners, lawmakers, and activists worked together to propose a river management strategy that focused on restoring the natural flood control features of the river and incorporating engineering technologies to protect downtown homes and businesses from flooding. The Measure A half cent sales tax was introduced to the 1998 ballot to fund the project and overwhelmingly approved by voters.
A set of living river objectives were developed by the community to establish a framework to guide the project. As construction began on the Napa River and Creek Flood Control Project, the living river concept came to life. The county began to acquire land along the Napa River to begin to restore the river’s natural floodplain. South of downtown, agricultural dikes were removed from farmland and businesses prone to frequent flooding were moved to create space for the river to rise and fall during storms. Much to everyone’s surprise, once the water was allowed to flow back onto these lands the wetlands quickly reestablished themselves, creating over 900 acres of habitat for wildlife and improving the quality of water in the river for fish. Reestablishing the wetlands also helped increase the tidal prism (area where tidal waters from the bay can flow), reducing the tidal influence farther upstream. Terracing of the land along the river, both south of downtown and upvalley, has reduced channeling of the river and provides space for the river to spill over without causing damage to property.
The next phase of the flood control project was the construction of several bridges to better accommodate the flow of the river and the streams feeding into it. Wider and higher bridges allow more water to flow by removing choke points that contribute to flooding. New bridges downtown along First Street, Third Street, Imola Avenue, as well as over Milliken Creek and upvalley on Zinfindel Lane no longer catch debris, dam water flow, or prevent fish from moving upstream. The Napa Valley Railroad was also moved to accommodate the flood bypass park known as Oxbow Commons, another central element of the flood control project.
One of the most critical aspects of the flood control project was helping water flow through the oxbow district without flooding downtown. Saving the oxbow feature of the Napa River was important not just for aesthetics and preserving the natural bend of the river, but also for reducing silting of the river in flood prone areas. The curve of the river helps slow sediment transport, maintaining the quality of the water but also slowing it’s flow. Strong floodwaters naturally want to take the path of least resistance, which happens to be straight through downtown Napa. The solution is a wet/dry bypass that provides floodwaters an escape while preserving the natural shape and flow of the river during normal flows. In the rainy season, the bypass is designed to allow the river to overflow where it naturally wants to overtake the banks and flow through the park to meet the Napa River farther downstream. In the dry season, the park can be used for recreation and community events. Good for residents, visitors, and the river alike, the Oxbow Commons bypass has quickly become a gathering place in the community while providing critical flood protection since it’s completion in 2015.
Aesthetics have played an important role in flood protection and the revitalization of downtown Napa. Designed to preserve the charm of downtown, attractive floodwalls form the Napa River Promenade and renewed Veteran’s Park while keeping water out of the downtown area and providing views of riparian habitat and floodplain restoration across the river, balancing economic development with environmental preservation. Replacing bridges that impede river flow during storms with graceful structures spanning the river removed choke points in the river while keeping businesses open and traffic flowing during storms. While creating an attractive downtown for residents and visitors to enjoy was always a priority of the living river design, the economic benefits of the finished projects exceed expectations as the downtown district began to flourish and thrive once again.
The living river concept lives on beyond the Measure A flood project, influencing and shaping land use decisions and policies throughout the county as well as receiving national and international recognition for innovative environmental design. Napa’s flood control project is considered a standard for flood control design, has received numerous awards, and has served as a model for other communities. The Napa County Resource Conservation District continues to promote these concepts with landowners up and down the valley to maximize land use while minimizing environmental impact. The grassroot efforts of the FONR have established a strong voice for environmental advocacy, problem solving, and activism in the community, proving that neighbors can come together to solve complicated problems and make positive impacts in their hometown and beyond.
Check us out! Books and resources available from the Napa County Library:
1). Flood Warning by Katharine Kenah
2). The Science of a Flood by Meg Marquardt
3). Watch Over Our Water by Lisa Bullard
4). Save Our Stream by Colin Polsky
5). Why Water's Worth It by Lori Harrison
Go deeper! Explore these great resources online:
Oxbow Preserve Self-Guided Tour
Friends of the Napa River History of the River video
US Army Corps of Engineers Napa River & Creek Flood Protection Project Overview Video
San Francisco Estuary Institute Napa River Case Study
Napa County Realtime Rainfall and Stream Data
Dive In! Citizen Scientist & Community Enagagement Opportunities:
Napa County Streamwatch
Napa County Resource Conservation District Volunteer Opportunities
iNaturalist Napa River Watershed Observations
Cornell Lab of Orthinology Nest Watch Program
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