Down By The Bay: Exploring the Estuary of Wetlands Edge Park and the Napa River & Bay Trail

It’s easy to forget how close the Napa Valley is to the ocean, but a quick trip to American Canyon reminds us how connected our watershed is to the sea.

With sweeping views of San Pablo Bay and the Napa-Sonoma Marshes, the Wetlands Edge Park estuary is a remarkable story of resilience and restoration in the Napa River Watershed.

The wetlands, waterways, grasslands and hills you see in the park are all part of the Napa River Watershed. Miles of trails with interpretive signage explore the troubled history of land use and the impressive rebound the wetlands have made after intensive restoration efforts by local agencies. Now a haven for wildlife, walkers, runners, bikers, and birders, the Napa River and Bay Trail showcases the beauty and importance of wetland ecosystems and how powerful it can be when a community comes together.

Before the California Gold Rush ushered in extensive settlement and development, the San Francisco Bay, including San Pablo Bay, was edged with vibrant marshes that extended inland several miles. Just 100 years later, 85% of those marshlands were diked or filled. Historically, wetlands and marshes were viewed as wastelands because of challenges they presented for agricultural and industrial development. Poor drainage and frequent flooding make these lands difficult to build upon, and the salty mix of ocean and freshwater is not favorable for growing crops. In some areas, attempts were made to drain the wetlands and create farmalnds and ranches for cattle grazing. What couldn’t be drained became dumping grounds for household waste.

In the park, Glass Beach, Good Luck Bay, and the landfill mound are all evidence of how until recently the value of the wetlands was not fully understood. Pits were dug into drained marshes and filled with refuse from all over Napa and Solano counties before being covered with soil. Over time, the tides of the bay and the current of the river eroded these primitive landfills, tumbling the glass and ceramic shards to create the white, green, and blue gemstone like sands on Glass Beach. Next to Glass Beach sits Good Luck Bay, another colorful but even more harmful example of dumping in the wetlands. As recently as the 1950s and 1960s, trash was being burned at this site and toxic waste was dumped to be taken out by the tide, creating the bright pink soil we see there today.

Luckily, waste management has evolved and a more controlled landfill was developed. The flat topped hill you see is an improvement from the days of dig and dump; laws and programs now divert toxic waste and recyclable items from landfills. An extensive system of pipes and wells collects contaminated water that trickles down through the trash heap and sends it away to be treated before returning to the water supply. Carbon dioxide and methane gases are trapped and converted to energy: this landfill alone generates enough electricity to power 10,500 homes! Since 1990, the landfill has been capped and the land around the landfill has been restored to tidal action. Cars, appliances, and other debris that were been dumped over the past century have been removed from the marshy areas to make the park safe for wildlife and people to enjoy.

In addition to improved waste managment and capping the landfill, the end of the 20th century also began the transformation of industrial use areas back into tidal wetlands. Starting in the 1950’s, the Leslie Salt Company, and later Cargill Incorporated, used diked wetlands to build large evaporating ponds for salt production. The intense sun and winds from the bay evaporated the sea water, concentrating the salt in the ponds for harvesting. These large evaporating ponds created brines (concentrated salty water) where even the hardiest plants cannot grow. Salt production had a disastrous effect on the wetlands, making it difficult for wildlife and plants to survive. Since the 1990s 11,400 acres of land formerly used for salt production by Cargill Incorporated have been sold to the State of California for rehabilitation. In 2006, the California Department of Fish and Game, the Wildlife Conservation Board, and partners began the restoration of those low-lying floodplains to create tidal and seasonal wetlands. To restore the wetlands, the wooden barriers between the evaporating ponds have been removed and levees have been opened to allow the Napa River to once again flow through the wetland area, reducing the concentrated salinity caused by the evaporation pools and allowing plants, fish, and other wildlife to return. Cleaned water is also pumped in from the nearby wastewater treatment plant, replenishing water diverted from the river upstream and further restoring the natural balance of the wetlands.

Now that balance is returning to the wetlands, the estuary is teeming with wildlife. Over 300 species of wildlife call Wetlands Edge Park their home. Improvements in water quality have brought Chinook Salmon and Steelhead Trout back to the wetlands and up the Napa River to spawn. Otters, seals, and other mammals have returned to fish and play. Shorebirds, songbirds, and birds of prey feed and nest in the restored tidal mudflats. Migratory fowl stop to feed and rest as they migrate along the Pacific Flyway each year.

The Napa-Solano Audubon has posted signs about the different birds you might see along the trail, making Wetlands Edge Park a fantastic place for the beginning birder. Keep your eyes open for Northern Harriers and Great Horned owls perched in the eucalyptus grove or Yellow-rumped Warblers flitting between the canopy and the wetlands during the winter months. Down by the water you may spy Common Gallinule using their wide webbed feet to walk through the plants and mud on the wetland’s edge. Green Winged Teal swim around the ponds using their beaks to filter invertebrates out of the water. Long beaked American Avocet do the same along the mudflats by swinging their beaks from side to side. The world's smallest shore bird, the Least Sandpiper, scurries around the mudflats picking food from the surface during its winter stay. In the spring, the sandpipers will migrate to Canada and Alaska to breed. Now a thriving ecosystem, Wetlands Edge Park provides fantastic bird watching year round.

The health of the wetlands is important to both animals and people alike. In addition to wildlife viewing and breathtaking views, healthy wetlands help provide a barrier between urban development and rising sea levels. Wide floodplains of the wetlands accommodate abrupt changes in water levels during storms and slow the river’s flow to prevent flooding upstream. The plant-rich environments along the wetland’s edge filter pollutants and sediments from the water, supporting the overall health of the river and the water supply. They also provide recreation opportunities such as biking, fishing, and jogging for the local community to enjoy.

Once just a swampy nuisance, these wetlands are now recognized as a critical component of the watershed ecosystem. Decades of misuse are being reversed through the dedication and care of the American Canyon and Napa County communities, and make Wetlands Edge Park a shining example of the positive impact we can have on our watershed to make it a better place for everyone - and everything- to be.

Check us out! Books and resources available from the Napa County Library:
1). Super Simple Wetland Projects by Carolyn Bernhardt
2). The Secret Bay by Kimberly Ridley
4). All About Wetlands by Christina Mia Gardeski
5). Marshes and Swamps by J.K. O'Sullivan (includes science experiments)
6). Marshes and Swamps: A Wetland Web of Life by Philip Johansson
7). DVD: Bill Nye the Science Guy: Wetlands

Go deeper! Explore these great resources online:
VIZZIT Interactive Audio Walking Tour
Wetlands Edge Park Trail Brochure
Chart of Bird Sightings by Season in Wetlands Park
Video: History of the Napa River Bay Trail

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