The Bay Trail — Ride #20 — Map 20 — Hamilton Wetlands and Las Gallinas Valley Sanitary District

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This was my twentieth bike ride on my quest to travel 350 miles of the San Francisco Bay Trail completed so far.  The Bay Trail vision is a single trail of 500 miles that encircles the entire Bay, going through 9 counties and 47 cities. 

At the end of August 2022, I followed Map 20 of the Bay Trail first along the Hamilton Wetlands Restoration Area and later around the Las Gallinas Valley Sanitary District treatment ponds, both following the east shore of San Pablo Bay.  The two sections of the trail run through the communities of Novato, Bel Marin Keys, St. Vincent, and Gallinas.

In Novato, I drove south on Nave Drive, east on Hamilton Parkway, and then south on Hangar Drive to South Hamilton Park.  I parked in a public parking area near the ball field and picked up the Bay Trail to arrive at the entrance to the Hamilton Wetlands area.

A sound wall separates a group of homes from the Bay Trail and the nearby wetlands. The Bay Trail follows the top of a levee for 3 miles from here.  At the entrance to the wetlands area, I was greeted with information I have come across before: “Tidal wetlands help buffer sea level rise and serve as natural sponges, absorbing and slowly releasing stormwater.” They help maintain an even climate, provide erosion and flood control by absorbing wave energy from storms, and benefit Bay fisheries. They trap CO2 and sequester carbon which helps with global warming. And the wetlands grow upwards as sea level rises. 

Plants in this area include one I had not heard of: Coastal gumweed, with yellow flowers, that can grow 3 feet tall.  The wetlands are home to the endangered salt marsh harvest mouse and the California clapper rail. American avocets frequent this area. Art work by local students is displayed along the trail depicting native creatures such as the Gooey-Duck clam, the Ridgway’s Rail, the California Black rail, the Salt Marsh Common Yellowthroat, the Black-necked stilt, the burrowing owl, the Darner dragonfly, the Lined Shore crab, the Pumpkin spider, the Black-tailed Jack rabbit, the Mule Deer, Coho salmon, marsh gum plant, coyote bush, and the Sea Sparkle (a unicellular microorganism known for its ability to bio luminesce, giving the water a bright blue glow seen at night).

The trail was packed sand.  At the entrance, to the right (south) was a creek flowing into the marsh area. Part of the creek water was very red, as though full of some type of sediment, and then it quickly turned blue as it reached the marsh water. To the left, Mount Burdell rose up from the horizon and Mount Burdell Open Space Preserve.

This wetland area has been here for a while with some restoration projects completed in 2015. Interpretive signs have become corroded by the salt air and are difficult to read.

At one time, around 1900, the area was diked to create land for farming, not unlike the Sonoma Baylands of  Ride #19.

The Hamilton Army Air Corps Base was established here in 1934, named for First Lieutenant Lloyd Andrews Hamilton who won the Distinguished Service Cross in 1918 during World War I. In 1947, the airfield was transferred to the U.S. Air Force.  When it was deactivated in 1974, Federal, State and local officials decided to restore the area to wetlands using clean dredged materials.  (To allow safe navigation of cargo ships in the San Francisco Bay, three to six million cubic yards of sediment must be dredged each year.) As with the Sonoma Baylands, the restoration required raising the land level so that the soil could support tidal wetland plants and animals when the levee was opened to reintroduce tidal action.

Past the residences, further up the left (west) side of the trail, are several buildings, old hangars from the Air Force days. Lettering on some of the buildings says “U.S. Coast Guard,” suggesting they are still in use. 650 acres of former concrete runways have been restored to wetlands.  There are plans to restore another 1800 acres of neighboring parcels as well.

At the north end of the trail, one can bear right to ride along the east side of a body of water that flows into Pacheco Pond and borders Bel Marin Keys Boulevard to the north. This trail is narrower, still dirt, and rather rutted. 

The water was filled with floating groups of American white pelicans, the largest gathering I’d seen for several Bay Trail rides. They stayed close to the water’s edge, making it tempting to shoot hundreds of photos of them as they dipped for plants and fish and then raised their bills to swallow. When they are flying or when the wind blows, you can see black feathers fluttering underneath their white wingspan. Great white egrets and snowy egrets kept them company.

Further along the trail, I passed a farm on the right with a few stacks of bales of hay. Later I passed a meditation and retreat center. A eucalyptus tree leaned over the trail.  I’ll bet it has fallen in the winter 2023 wind and rains.

Once I had returned to the beginning of the trail, I continued south and followed it around the south side of the marsh. There were wooden benches where I stopped for lunch. The trail ended a little further at a “No Trespassing” sign.  It appeared to continue on a levee headed further south, bordering farm land with tractors involved in harvesting with irrigation going on.  Though the Bay Trail has a break here, it is headed towards the Las Gallinas Valley Sanitary District and Gallinas Valley Birding Loop.

Later, when I had driven down to the Las Gallinas Valley area, I saw cyclists riding along a trail headed north to where I had lunch.  I believe there were no signs stopping them from riding coming from the south, although there were from the north.  The Bay Trail website says there are plans to link these two sections of the trail at some point.

In the unincorporated community of Gallinas, at the Las Gallinas Sanitary District, is the Las Gallinas Sanitary District Wildlife Area.  At McInnis Park, I followed Smith Ranch Road to the end and then followed the signs to the Las Gallinas area. Here, the Bay Trail is also called the Las Gallinas Valley Sanitary District Trail—approximately 3.5 miles to walk or ride from the parking lot/trailhead—which circles a “Wildlife Pond” and wastewater processing Ponds 1 and 2, separated by a levee from Miller Creek. While there are signs warning not to consume the wastewater being processed, a great variety of waterfowl enjoy the area and don’t seem to mind the water a bit. An interpretive sign says, “This segment of Bay Trail will take you past the treatment ponds where birds and birdwatchers gather, then out to the District’s outer levee seemingly miles from anywhere.”

The primary function of the ponds is to act as storage for recycled water. The secondary-treated recycled water is used to irrigate District pasture land, landscape for the Marin Municipal Water and North Marin Water districts, or is released into Miller Creek between November and June. Miller Creek drains east into San Pablo Bay. Pond levels are at their lowest in the summer months.

From time to time, an overabundance of cattails is removed from the Wildlife Pond, which increases the water surface area and reduces mosquito breeding areas.

In the Wildlife Pond, I wasn’t surprised to see many Canada geese but quite surprised to see some white swans. More American white pelicans were enjoying the water here. Like synchronized swimmers, they put their bills into the water together, then raised them up as they paddled forward. I also saw many snowy egrets and Black-necked stilts.

The bird-watchers are out early in the morning.  The S.F. Bay Trail website says that more than 185 species of birds frequent this area, including the Cackling Goose, Eurasian Wigeon, Osprey, Golden Eagle, Ferruginous Hawk, species of falcons and the Great Horned Owl. Bird viewing is supposed to be best in the fall through spring.

Finishing the circle around the Wildlife Pond and the other two ponds, I saw some type of long, narrow object—possibly a pipe—in the middle of one of the ponds, with many birds perched on top of it. The American white pelicans, cormorants and a few swans seemed to alternate positions. One pelican spread his wings and revealed the hidden black under-feathers.

Hopefully, the next time I come to this area, the Bay Trail will be connected to the Hamilton Wetlands area for a longer, scenic ride. I rode for about 3 and a half hours this day. My total ride was 9.55 miles, half of which were return miles.  My odometer had now reached 284 miles for all riding so far along the Bay Trail.

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Funding and sponsor organizations and contributing partners:

Hamilton Wetlands Restoration Area and Bay Trail:  Coastal Conservancy; San Francisco Bay Trail; U.S. Army Corps of Engineers; Save the Bay; The Bay Institute; Marin Audubon Society; Marin Conservation League.

Permits and Approvals from U.S. Environmental Protection Agency, Bay Conservation and Development Commission, Regional Water Quality Control Board, U.S. Fish and Wildlife Service, National Oceanic and Atmospheric Administration, and California Department of Fish and Game.

Las Gallinas Valley Sanitation Area and Gallinas Valley Birding Loop: Las Gallinas Valley Sanitary District;

Information sources:

S.F. Bay Trail website, Map 20; interpretive exhibits (information boards) along the Bay Trail; S.F. Bay Long-term Management Strategy – Dredging

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