Biology Reference
In-Depth Information
BRACKISH WATERS AND SUISUN MARSH
Suisun Bay, up beyond the span of the Benicia Bridge, may seem remote to
many metropolitan residents, but it is a familiar and age-old destination for
hunters. Hunters have come to this vast marsh for 130 years to shoot ducks—
more than 158 privately owned clubs manage baylands here as waterfowl
habitat. The shores of this upper bay include two of the largest natural tidal
marshes in the estuary: Brown's Island and Rush Ranch. But the area is better
known for its 52,000 acres of diked wetlands, more fresh water than salt
water, that are unique among bay habitats. Upstream water managers have
been required for many years to release enough fresh water downstream to
keep Suisun brackish, and to manage salinity barriers with the same goal.
Scientists say Suisun Marsh is critical to the ecosystem. “It's the region of the
estuary where everything changes rapidly,” says wetland planner Stuart Siegel.
“In relatively close proximity are very different environments, so if you're a fish
you can find what you need without going far.” From east to west, Suisun
changes from nearly fresh water to salt water within a span of 15 miles. These
changing estuarine conditions, in a relatively untouched landscape only
slightly subsided below sea level, make Suisun Marsh a priority target for those
seeking to restore habitats for endangered smelt, splittail, and other species.
Planners hope to restore at least 7,000 acres of tidal wetlands in Suisun
Marsh, as well as brackish and seasonal wetlands.
On Cullinan Ranch managers face challenges now nearly universal for
Bay Area restoration projects. “No-work” windows designed to protect
endangered species don't always coincide with periods best for construc-
tion. Christy Smith says that, at Cullinan, such restrictions mean work can
be done for only two or three weeks out of an entire year. This makes res-
toration planning a juggling act. “When we breach Cullinan, we have to do
it when the salmon are not migrating, but after the breeding season of Salt
Marsh Harvest Mice, and in the middle of winter when we already have a
sheet of water out there, and the coyotes and rabbits have already retreated
to high ground, and it will only take a little more water to flush the re-
maining critters onto the levees. Then we have to wait for a high tide to
dilute that water before we release it back out to the slough, because it'll
have been sitting in there for a while, might have turned anerobic, and
could pollute the slough.”
Whether looking at a map or out from a Highway 37 bridge, it is easy
to see the elements of a future landscape that resembles the bayshore's
historic mosaic of vegetation, water, mud, and grassland. These future
marshes will also help filter out pollutants from runoff, absorb floodwaters
from the Napa and Petaluma rivers so they don't creep over sandbags and
