Alviso Slough Trail: Don Edwards National Wildlife Refuge

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The Don Edwards National Wildlife Refuge covers a significant portion of the marshland and shoreline at the bottom end of San Francisco Bay: in fact, most of the shoreline southeast of the Dumbarton Bridge.  It is a wonderful place to go for a flat walk with unusual perspective of the ridgelines surrounding the south Bay Area.  This was a 9-mile loop starting from Alviso Marina County Park and following the Alviso Slough Trail on levees surrounding several salt ponds separated by other levees.  This loop is part of the San Francisco Bay Trail.  I made a short detour to a portion of the Mallard Slough Trail where there is a connection between the two loop trails.  The Marina trailhead is near the lower right of my GPS track, and I went around the loop clockwise.

GPS track

GPS track

The two highlights of this walk were the wonderful views of the major south bay peaks across open water and the extensive bird life.  I had not anticipated the over-water views, so when I first noticed this view of Mission Peak, Mt Allison, and Monument Peak I was simply delighted.  They are about 8 miles away to the northeast.  Note the gulls and other birds resting on the small island in the salt pond.

image of Mission Peak, Mt Allison, and Monument Peak from Alviso Slough Trail

Mission Peak, Mt Allison, and Monument Peak from Alviso Slough Trail

This picture was taken later in my walk but illustrates the network of levees separating salt ponds in the south Bay.

photo of levees separating salt ponds

Levees separating salt ponds

As I walked along the trail I heard a plane taking off from nearby Moffett Field (formally Moffett Federal Airfield, and home of NASA Ames) and, sure enough, shortly it flew overhead.

picture of Air Force plane after takeoff from Moffett Field

Air Force plane after takeoff from Moffett Field

Most of the first 3½ miles of the loop runs parallel to Alviso Slough as it snakes from the lower end of the Guadalupe River to San Francisco Bay.  The coastal hills of the Peninsula, technically part of the Santa Cruz Mountains, are in the background.

image of Alviso Slough

Alviso Slough

About 3.6 miles from the trailhead I had a stunning view of Mt Umunhum (on the right) and Loma Prieta (on the left), nearly 20 miles away and almost due south, over the open shallow water of a salt pond.  Almost unbelievably, this view also looks over the heart of the Silicon Valley, including the cities of Santa Clara, Sunnyvale, west San Jose, and Campbell.

photo of Mt Umunhum and Loma Prieta from Alviso Slough Trail

Mt Umunhum and Loma Prieta from Alviso Slough Trail

The air quality in the Bay Area has been generally poor recently, due in large part to unseasonably warm and dry weather.  On the day of my walk, however, the air was clearer than it had been for several weeks, and Mt Tamalpais’ distinctive “sleeping maiden” profile was clearly visible in Marin County, some 45 miles away to the northwest.  This picture was taken about 4.1 miles from the trailhead, at the farthest northwest point on the trail.

picture of Mt Tamalpais across salt marsh and levees

Mt Tamalpais across salt marsh and levees

Another treat was viewing Mt Hamilton across the salt ponds, in which the water surface was generally quite calm.  In this view the water is so calm that the hills and clouds made beautiful reflections.  The white Lick Observatory buildings can be seen on the skyline.

image of Mt Hamilton reflected in a salt pond

Mt Hamilton reflected in a salt pond

Continuing around the loop I had continuous views of the surrounding skyline, and it was most delightful.  As I got a little farther along I was in a position, relative to the sun, to see sunlight reflected from the water surface.  In this view the high point on the skyline is Black Mountain, about 12 miles away to the southwest, with Moffet Field’s distinctive hangar directly in my line of sight.

photo of Black Mountain and Moffett Field across the twinkling water surface

Black Mountain and Moffett Field across the twinkling water surface

About 5.5 miles from the trailhead, about halfway across the north leg, I came upon a structure that I believe surrounds a tidal gate, reminiscent of gates I’d recently seen in the North Bay at Rush Ranch.  Typically these gates are adjusted a few times a year to manage the water level and salinity in the salt ponds within the levee system.

picture of tidal gate

Tidal gate

As I continued around the loop I heard the distinctive toots that signaled a train approaching the area.  Until then I hadn’t fully appreciated that the Amtrak tracks run along one of the levees, part of the rail route from Oakland to San Jose.  In a few minutes the train was in front of me, almost appearing to float on the water.

image of Amtrak train on its way to San Jose

Amtrak train on its way to San Jose

At that point I finally understood why there was only a single trail connector between the Alviso Slough and Mallard Slough trails, which run parallel to each other and quite close together for about 1 mile.  The connector is the only place where there is an intersection of levees that facilitates getting across a narrow (10 yards or so) waterway between the trail levees and the railroad track levee.  Before I left the trailhead I had made a tentative plan to use the trail connector to go over to the Mallard Slough Trail and walk up to its north end, about 0.6 miles away.  This is exactly what I did, and it was interesting to be walking parallel to the train tracks, separated by the narrow waterway.  At the north end of the Mallard Slough Trail loop there is a little overlook where you can view the very low bridge that takes the railroad tracks across the slough that forms the terminus of Coyote Creek.  Across the slough is Station Island, which apparently once hosted the bustling town of Drawbridge, where locals came to hunt and experience the Bayside environment.

After enjoying the view I returned to the Alviso Slough Trail and made my way back to the trailhead, periodically turning to look once again at the ridgeline views and nearly all of my favorite Bay Area peaks.

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One Response to Alviso Slough Trail: Don Edwards National Wildlife Refuge

  1. Pingback: Birding along Alviso Slough Trail at Don Edwards National Wildlife Refuge | trailhiker

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