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This was my fourteenth bike ride on my quest to travel 350 miles of the San Francisco Bay Trail – those miles completed so far of the total of 500 miles planned – this time continuing north along the east side of the Napa River, following Map 18.
There is a small parking lot at the intersection of Wetlands Edge Road and Eucalyptus Drive in American Canyon. First, I rode south on Wetlands Edge Road — about 2.8 miles round trip. This part of the Bay Trail is a wide city sidewalk with views of the marshlands to the west. Leaves of a Fremont cottonwood rustled in the wind.
I could see an upland area across the marsh, closed to the public, which supports oak, coyote brush, goosefoot weed, alkali heath, and brass buttons. From 1942 to the 1990’s, the 300-acre site operated as the American Canyon municipal landfill, now rising 40 feet above the edge of the Napa River. Approximately 178 acres around the landfill have been restored to marshland. The landfill has been closed and capped, trapping methane gases. The gas is piped to a nearby building which uses the methane to generate electricity. Goats eat the weeds that grow around the pipes.
Riding west from the parking area, I came to the Mike Thompson Loop Trail which circles the base of the landfill. Be warned that the fence keeping the public off the upland area is an electrified fence. There are only a few signs warning of this.
On the west side of the landfill, I passed Glass Beach. Just north is a gate with a bike trail passing around it. Past the gate, the dirt trail turns east towards the power plant. Before the plant are two trail options. One follows the east side of some type of canal; the other runs on the west side of the canal and along the water’s edge – the better trail to ride on. Both lead north alongside the Napa Plant Site Restoration Project, some type of wetlands restoration. On the Bay Trail map, it looks like an expanse of land, but actually I was riding right alongside the water. Most of trail was dirt; once again, I was glad to have the mountain bike.
I heard a low booming sound come floating across the water that I couldn’t identify. A steady tone, a much lower bass sound than a fog horn. A fog horn starts at a medium tone and then drops to a lower tone for its second blast. This sound was constant. But I soon forgot about it.
Nearby mountains peaks define the Sonoma River and Napa River Watersheds. Viewing poles guide visitors to the nearby peaks: Sonoma Mountain, Mount Veeder, Sugarloaf Peak, Twin Peaks in San Francisco. The waters, wetlands and uplands of the Napa River Bay Trail are part of this interconnected watershed system draining into the San Francisco Bay. Forty-seven tributary creeks flow into the Napa River. The watershed is home to over 100 million people and a lengthy list of wildlife: 75 bird species, deer, bats, grey fox, raccoons, bobcats. It is located on the Pacific Flyway, the migratory bird route from Canada to Mexico, used by 400 species of birds throughout the year.
One information panel had the most complete list of wild creatures frequenting this area of any I’ve yet seen (see Notes). It was the first to mention the North American beaver. Beavers have resumed residence in Martinez as well as in the South Bay watershed area.
Tidal marshes are the lowest lying areas along the Bay shoreline, flooded here by tides twice each day from the Napa River and San Pablo Bay. They are home to shorebirds, waterfowl and passerine (perching songbirds). Great blue heron, great egret, American coot, killdeer, northern harrier, San Francisco common yellowthroat, mallards, Virginia rails, willets, California black rails, California clapper rails, as well as salt marsh harvest mice and other rare, endangered species call this home.
The seasonal wetlands — grassy meadows, ponds and mudflats – are flooded only part of the year and are dry in summer. This provides important feeding and refuge for wildlife when the tidal lowlands are deeply flooded. Willow and salt grass grow here.
The transitional zone and seasonal wetlands are home to invertebrates as well as birds like the killdeer, black necked stilts, greater yellowlegs, and great and snowy egrets. Cattail, bulrush, and rabbits foot grass grow here.
Plant types vary depending on conditions: Bulrushes prefer fresher water; Pacific cordgrass grows along the lower edges of the marsh; pickleweed dominates the high marsh; salt grass, marsh heather and fat hen grow in transitional zones between the tidal marsh and upland habitat.
All along the Napa River, these tidal marshes are being restored and salt pond restoration is in progress. The sloughs in this area had been cut off from tidal action for 70 years by a levee which failed in 1997 due to heavy flooding. During those 70 years, the land sank several feet, too low to support marsh plants. In 1998, the City of Napa partnered with the U.S. Bureau of Reclamation to restore 460 acres of shoreline. This involved converting former wastewater ponds to tidal wetlands, restoring degraded wetlands, and creating the park and trail system in this area. Now that tidal action has been restored, sediment will deposit here to support the return of adapted plants and wildlife.
American Canyon is the second largest city in the County of Napa and was incorporated in 1992. The first people of American Canyon (Napa Valley and the lower Napa River) were the Patwin, Coast Miwok, and Wappo. They hunted elk, deer and bear; they fished the creeks and marsh sloughs and gathered shellfish such as mussels. They harvested native plants and acorns.
The Spanish and Mexican explorers arrived in the late 1700’s when nearby Mission Sonoma was established. Many Native Americans were forced to work on the ranches and were impacted by a smallpox epidemic in the 1830’s. After 1848, many were pushed from their lands onto reservations elsewhere.
In 1848, Mexico gave 84,000 acres, called Rancho Suscol, to General Mariano Vallejo. In 1862, the U.S. Supreme Court invalidated the ranch as a legal property and the land became public domain, open to homesteaders.
In the 1880’s, the Northwestern Pacific Railroad and Southern Pacific Railroad extended their lines north through Napa Valley, south to Vallejo, and west to Santa Rosa. Napa Junction – the original name for American Canyon – was an important connection point for the rail lines located east of Highway 29. The Napa River was used extensively to transport goods to San Francisco and Oakland through the early 1900’s.
In 1919 the Clark brothers bought the land in this area, raising beef cattle, oats and hay. The marshlands were drained in the 1930’s, including the low-lying lands to the west of Wetlands Edge Road and south of Eucalyptus Drive. The Clark brothers continued to work the land after they sold it to the Zunino family in the 1940’s
In the 1950’s, Cargill Salt Company established commercial salt ponds along the Napa River. By then, 85% of the San Francisco Bay marshlands had been diked or filled.
In 1989 the Port of Oakland purchased the land from the Clark brothers. In 1998 the land was sold to American Canyon to begin the wetlands restoration project.
In 2006, American Canyon restored its low-lying flood plains in the area to tidal and seasonal wetlands.
One information sign claims that salmon was once so plentiful that old-timers could walk on the backs of the salmon to cross the Napa River. Restoration work along the river has halted the decline of Chinook salmon and steelhead trout and begun the slow recovery of its numbers: barriers are being removed that blocked fish migrating up river to spawn; erosion is being controlled to reduce sediment that clogs the sand bars; pollution from fertilizers and pesticides is being reduced.
I am familiar with the salt harvesting done in the south and middle portions of the San Francisco Bay but was not aware much was done along the Napa River. First the Miwok and Ohlone people collected salt from small natural evaporation ponds. By the 1850s, commercial salt harvesting increased as salt was needed for the silver mining process and to cure meat for long-distance rail shipping.
I followed the Bay Trail north along the eastern edge of the Napa Plant Site Restoration Project. Small planes soared overhead from the nearby Napa Valley Airport. The Brazos railroad bridge stood up from the horizon. When the trail came to an access road, I followed it west to a small parking area with a bathroom building and an interpretive sign. Then I heard the low booming sound again. Still very loud, floating across the water; still unidentifiable.
A dirt trail led further west to another sign and a bench. I stopped here for lunch: ham, cheese and avocado sandwich cooled by the ice-filled water bladder; peanuts and filberts; apples in lemon juice; dried Blenheim apricots.
As I ate, I looked across the Napa River where homes lined the water’s edge as far as the eye can see. Mud Slough was to the west of me, flowing south out of the Napa River. Former pickle ponds from the salt restoration days were to the northeast, the Brazos railroad bridge on the far side.
The trail curved left to the south, for about 3/10 of a mile. It’s worth following it to the end for more views of the water.
There were very few people on the trail, even though it was a Saturday. Was it because people work or do shopping on Saturday? I wondered how busy it would have been on Sunday. I passed at most 10 cyclists and as many walking. Very few were out with their dogs.
There was a strong constant cold wind. I wore my brushed cotton, rose plaid overshirt all day. About 2 p.m. the wind picked up. Boating friends have shared that they go out in the morning and get off the water before 2 p.m. because of the wind increase and the rougher waves.
I was surprised to learn that one of the most important industrial salt production sites was along the Napa River. Leslie Salt diked farmlands not far from the Napa airport in the mid-1950’s, creating a series of salt-harvesting evaporation ponds. It took ten years of preparation before salt production could begin in 1961.
Salt water was pumped from San Pablo Bay into over 11,000 acres of these evaporation ponds. The evaporation process took about five years. The harvested salt was stored in tall piles that looked like sand dunes, then shipped by rail car to barges that crossed San Pablo Bay to Antioch where the salt was used to produce refrigerator coolant. Cargill purchased the facility in 1978 and sold salt to Dow Chemical for its manufacturing processes as well as to British Columbia for de-icing winter roads. Of course, the salt was also sold to consumers and as salt licks for livestock.
An information sign provided a recipe to harvest the salt:
- Pump water from San Pablo Bay at 15 parts of salt per thousand (ppt) of water; place in concentrator pond
- Let sun evaporate pond water to create a brine of 145 ppt
- Pump brine under the Napa River (they don’t say how) into pickle ponds for evaporation to 300 ppt
- Let brine dry to crystal form (355 – 369 ppt); harvest 6-inch layer of salt
In 1994, the California Department of Fish and Game and the Wildlife Conservation Board purchased the acreage and have reintroduced tidal flow to restore the wetland ecosystem. The California Department of Fish and Game manages the 14,000 acres of the Napa-Sonoma Marshes Wildlife Area and Fagan Marsh Ecological Reserve. The Fagan Marsh reserve begins on the north side of the pickle ponds, with the Napa River on its west border and the Napa airport to the east. The Bay Trail plan is to extend the trail north along the east side of this reserve, past Bull Island, and along the east side of the Napa River. When finished, it will provide an unbroken connection to Kennedy Park.
The delta tule pea can be found in the high marshes here. Steelhead trout are returning to Sonoma Creek and the Napa River. Burrowing owls call this area home. Black rails are found in the shallow marsh areas. Western snowy plovers find refuge on former salt pond levees. Western sandpipers forage in the mud flats. Delta smelt thrive in the brackish water where fresh and salt water mix.
By the end of the ride, I had heard the low booming sound often, sometimes as frequently as every twenty minutes. Could it have been a barge horn? The low bass note was intense, the lowest bass sound I’ve ever heard and always very loud, floating across the water seemingly from afar.
The Tuesday after my ride (7/26/22), I spotted this news item on the KTVU Fox 2 news feed: “Richmond Mayor asks for help solving ‘mysterious’ sound in city. . . . The thrum of a mysterious bass tone kept Richmond residents up from late Saturday night into the early hours of Sunday morning, so much so that the city’s mayor announced his office would offer a $500 reward to whoever could identify the source of the sound.” While the story said the sound was heard from Point Richmond to El Sobrante, I heard it 20 miles further north at American Canyon beyond where the Napa River and Carquinez Strait flow into San Pablo Bay.
One theory was that the sound was caused by the hum of the Golden Gate Bridge. The bridge’s humming noise was the result of a wind retrofit project in 2020 involving upgrades to the railing on the west side between its two towers. The humming occurs intermittently when fast northwesterly winds pass through the new railings causing noise as high as 100 decibels, similar to the sound of a jackhammer. Most affected have been those living in nearby communities such as Sausalito and San Francisco’s Presidio area; however, the strange humming has been reported several miles further away. A solution should be implemented by the end of 2022: a $450,000 plan to muffle the loud humming noise by the installation of thin U-shaped aluminum clips with rubber inserts on the railing pickets along the entire span of the bridge. The clips should lower the wind noise from 10 to 40 decibels. A reduction of 10 decibels lowers the sound by half.
On Wednesday (7/27/22) came the news that “[T]ipsters informed the mayor that the noise [had come] from a Brazilian event which lasted from Saturday night to Sunday morning. . . . ‘[P]eople fill up the beds of their pickup trucks with high power sound equipment and then they all get together in one place,’ the mayor explained. ‘It’s like a rave.’”
The organizers had posted the party on Eventbrite, saying that it would feature a Brazilian electro-funk phenomenon known as “Deboxe.” Some residents, unable to sleep, drove around the area, trying to locate the source of the sound. They “smartly guessed that the noise must be coming from a moving source” to avoid being caught for disturbing the peace.
My note: They say the party started at 10 p.m. that Saturday evening. However, I was hearing the sound as early as 12 noon Saturday. Could I have heard a different sound? Were they testing the sound equipment? Was it infrequent enough in the afternoon that people didn’t notice? I wasn’t in the area in the evening.
On this ride, I traveled 13.16 miles. My odometer had now reached 225 miles. Total riding time: 4’45”
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Wildlife thriving in this area include the yellow-rumped warbler, bobcat, Columbian black-tailed deer, coyote, jack rabbit, opossum, raccoon, salt marsh harvest mouse, tree squirrel, alligator lizard, Western fence lizard, garter snake, yellow jacket, West Coast Butterfly, Common Buckeye Butterfly, Cabbage White Butterfly, Orange Sulphur Butterfly, Mourning Cloak Butterfly, Monarch Butterfly, ladybug, honey bee, Bumblebee, and dragonfly. The area is also home to the mallard duck, mute swan, Northern harrier, Red-shouldered black bird, Red-tailed hawk, Snowy egret, Great egret, Great blue heron, Great Horned Owl, Turkey vulture, wild turkey, Canada goose, Barn owl, Anna’s hummingbird, American Avocet, Common Gallinule, Canvasback Duck, least sandpiper, house finch, western snowy plover, California black rail, California clapper rail, and killdeer.
S.F. Bay Trail website, Map 18; interpretive exhibits (information boards) along the Bay Trail; KTVU Fox News feed; Wikipedia.
Funding and sponsor organizations and contributing partners:
The Napa River Bay Trail: City of American Canyon; California State Fish and Wildlife Department; Napa County Parks and Open Space District
History of the Wetlands: www.firstpeople.org;
Return of Chinook salmon and steelhead trout: Napa County Regional Park and Open Space District; City of American Canyon
Salt Pond Restoration: Napa County Regional Park and Open Space District; California Fish and Game; Wildlife Conservation Board
Napa-Sonoma Marshes Wildlife Area: California Department of Fish and Game; State of California Wildlife Conservation Board
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