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It's
not your father's slough
A
new entrance to Moss Landing Harbor was dredged through
the
dunes in 1946. The historic mouth of the slough is at top; the
power plant now occupies the empty fields at bottom right.
The
earliest maps of Elkhorn Slough are almost two hundred years
old – simple drawings made by Spanish explorers. The latest
ones are the high tech versions produced by scientists striving
to understand the complex workings of one of California’s
last great estuaries. To the untrained eye the slough looks
pretty much the same in these maps – the figure S channel
snaking its way inland from the center of the Monterey Bay shoreline,
curving around the hills, marshes lining its banks. If you know
what you’re looking for, you can see the differences –
differences that make Elkhorn Slough today dramatically unlike
the slough of just a couple hundred years ago.
The most dramatic change came in 1947 when the U.S. Army Corps
of Engineers completed a new entrance to Moss Landing Harbor (photo,
above). As dramatic as that change has proven to be, it is only
one of many human actions that have altered Elkhorn Slough. The
first major change was the building of the railroad in 1872. In
1908 the Salinas River mouth was diverted so that, instead of
joining the mouth of the slough at Moss Landing, it emptied into
the bay four miles further south. For almost a hundred years,
roads, levees, tide gates, and dams were built throughout the
vast estuarine network that once linked Elkhorn Slough to Bennett,
Tembladero, and Moro Cojo Sloughs. Diked areas became pastures,
land was cleared for grazing, and, starting in the 1940s, row
crops began to be cultivated. In 1983, dikes on the Elkhorn Slough
Reserve were breached and the next year adjoining levees failed,
opening up hundreds of acres to tidal exchange.
Each of these changes had an impact on the mix of seawater,
freshwater, sediments, and wetland habitats that is the essence
of any estuary. Because each change has an impact on all future
changes, and because natural forces are also dynamic, it is
exceedingly difficult to correlate impacts to any one human
change in the system. This complexity has created a wealth of
opportunity for scientific study – but it also means makes
it harder to say “this action caused this result”
without a similar wealth of qualifiers. This article on human
changes and their impacts draws heavily on the work of many
scientists as summarized by Elkhorn Slough Reserve Research
Director Kerstin Wasson and Historical Ecologist Eric Van Dyke.
The
first great wave of change, the construction of tidal barriers
like levees, dikes, roads, and tide gates, began in 1870 and
continued into the 1950s. The result was a dramatic decrease
in the amount of land that was open to full tidal flow. Researchers
calculate that more than 37 miles of these barriers were built
between 1870 and 1956, reducing the area of unobstructed tidal
flow by 59%. During this same time period salt marsh declined
by 66%.
While the area exposed to tidal flow was being reduced, so was
the flow of freshwater into the slough. In 1908 the Salinas River
was diverted away from the slough, cutting the slough off from
what was then a major source of seasonal freshwater. The pumping
of groundwater over many decades from the aquifer underneath Elkhorn
Slough has further reduced the flow of freshwater from springs
and creeks. The result has been decreases in brackish tidal marshes
that were once common along the margins of the entire slough network
and which served as important transitional habitats.
This
hand-drawn diseño
from the Mexican land-grant era
shows
Moro Cojo as the top estero, with Elkhorn Slough below
it.
The next
great change was the construction in 1947 of the new, deeper entrance
to the Moss Landing Harbor, which created a permanent opening
between Elkhorn Slough and the ocean. The result was a dramatic
increase in the volume and velocity of tidal flow to the areas
that had not been diked. The volume of water exchanged on each
tide has nearly doubled since 1970. The main channel has gotten
deeper and wider year by year. Because there is more seawater
moving faster, bank erosion has also increased, with an average
rate of twenty inches a year in the upper slough and twelve inches
a year in the lower slough, with some areas eroding at a rate
of six feet a year. The increased tidal flow has also increased
the depth and width of the web of tidal creeks that spread out
from the main channel into the marshes. A study of 196 tidal creeks
showed an increase in their average width from eight feet in 1931
to more than forty feet in 2003. Not only is marsh land being
lost to the widening main channel and tidal creeks, the marsh
vegetation is being lost to bare mud. Marsh vegetation declined
from 90% cover to 46% cover between 1931 and 2003, with the most
significant decline occurring between 1949 and 1956, the years
immediately following the opening of the harbor mouth (graph,
above).
The increase in tidal volume and velocity is not exclusively the
result of the harbor mouth opening. As the channel and tidal creeks
widen and deepen, they create a feedback loop – as more seawater
pours in, it erodes banks and deepens channels, which create more
volume to fill, which increases the amount of tidal exchange.
Another component was added to this feedback loop in the 1980s
when levees were breached on the Elkhorn Slough Reserve. Because
there was more land open to tidal water, the volume of tidal water
increased by an estimated 30%. One of the levee breachings, in
the area below the barn at the Reserve, was intentional –
the goal being the restoration of diked lands to tidal marsh.
The other, in the Parson’s Slough area to the south, was
unintentional.
Change
in the percent cover of marsh vegetation
in Elkhorn Slough from 1930 to 2003.
You can
get a picture of the cumulative result of all these changes by
looking at the two maps below. At a glance you can see two major
changes: a dramatic conversion of salt marsh to mudflats, and
the widening of the main channel and tidal creeks. Look more carefully
and you can see the loss of brackish tidal marsh habitat at the
north end of the slough and along the creeks that feed the slough
from the east. Today’s map shows the slough narrowing to
a creek after Hudson’s Landing, but earlier maps show a far
wider body of water running through Porter Marsh. It was likely
a mix of salt marsh and tidal brackish marsh fed by abundant underground
springs and Carneros Creek. And that mix of waters, freshwater
and seawater, is the biggest change effecting the slough during
the past 150 years. It may still look, more or less, like the
same S shape, but it's not your father’s slough.
This change wasn’t planned, and it is far from over. Unless
something is changed, Elkhorn Slough will continue to lose salt
marsh, its banks will continue to erode, and tidal currents will
continue to increase.
What
next?
Enter Barb Peichel and a cast of hundreds. In April 2004, Barb
was hired to coordinate the development of the Elkhorn Slough
Tidal Wetland Plan. The two-year planning process is a massive
one designed to address the complex problems that have resulted
from 150 years of human impacts to this dynamic – and rare
– environment. The project is funded through a grant from
NOAA (the National Oceanic and Atmospheric Administration) and
is jointly managed by the Elkhorn Slough National Estuarine Research
Reserve and the California Department of Fish and Game in collaboration
with the University of California Santa Cruz.
The project involves a score of scientists, key stakeholder
groups (including the Elkhorn Slough Foundation), and local,
state, and federal agencies. The goal is to build a shared vision
of what Elkhorn Slough should look like in the decades ahead
and to recommend ways to get there. It is a daunting task. When
Barb began work the most common words of encouragement were,
“Good luck,” followed by, “About time.”
We visited her this summer, half way through her two year project,
and found her optimistic. She pulled out a thick notebook and
flipped to the chart outlining the project’s timeline.
“We’re on schedule,” she said, smiling. During
the past year a Strategic Planning Team and a Science Panel
have met ten times.
The
mix of habitats in 1870 (maps by Eric Van Dyke).
A
hundred years of human intervention have produced
a very different mix of habitats and a wider main channel.
As one
of California’s few remaining estuaries, Elkhorn Slough has
been studied extensively by scientists. This summer some of these
scientists and others on Barb’s team were working to reach
agreement on what all this research told them. The next order
of business is to reach agreement as to what mix of habitats they’d
like to see as Elkhorn Slough’s future. Then the group will
recommend ways to achieve the results they want – how they
want to modify the slough that humans have created during the
past 150 years. At that point, their recommendations will begin
to wend their way through the various agencies that have a say
in what happens in Elkhorn Slough. The process, like the slough
itself, is a complex and dynamic one, and implementation –
and what will be implemented – is still years away.
“Implementation,” Barb says, “comes after the planning
– and after we get funding for implementation.” That
itself is a sea change for Elkhorn Slough. For the past 150 years
the fate of the slough wasn’t planned – it just happened,
step by step. Today, we’re planning for change – change
that will conserve, enhance, and restore this rare and threatened
resource.
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ESF
helps with staff, land acquisition
Last
year the Elkhorn Slough Foundation launched a campaign to raise
$20,000 to help the Elkhorn Slough Reserve cope with the impact
of the state budget crisis. A little over a year later, we have
raised more than $11,000 through this campaign. The funds have
been used to pay for staffing of the Visitor Center, which otherwise
might have been forced to close for at least some days each week.
ESF works with the Reserve in many ways, including hosting our
joint website and serving as the conduit for grants that fund
ten positions at the Reserve.
This summer we received word about another way we’ll be working
with the Reserve over the next few years – acquiring land
to add to the 1400-acre Reserve. ESF will use $1.9 million in
federal funds to acquire land from willing sellers. The funds
are from the National Oceanic and Atmospheric Administration and
were awarded to ESF by the California Department of Fish and Game
and the Wildlife Conservation Board.
“It’s a great partnership,” says Foundation Executive
Director Mark Silberstein. “The Reserve, and the public,
will benefit from our experience in land acquisition.” ESF
has acquired 2500 acres of land in over a dozen transactions over
the past eight years.
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Terms
frequently used in the stewardship work
of the Foundation staff
Tidal
barriers :
barriers that partially or fully limit the flow of
tide waters, such as levees, dikes, road or railroad
beds, and tide gates. By the 1950s more than 37 miles
of tidal barriers had been built in and around Elkhorn
Slough, reducing tidal flow to more than half the
former marsh lands of Elkhorn Slough. Today many of
these barriers have failed or been removed.
Steep
banks in the main channel of the slough
have been carved by tidal erosion.
Tidal
erosion : the process by which tidal flows
erode banks and channel beds, sometimes called tidal
scour. The average rate of bank erosion along the
slough's main channel is twenty inches a year in the
upper slough and twelve inches a year in the lower
slough. The average width of tidal creeks has increased
from eight feet to over forty feet in the last 70
years.
Tidal
volume: the volume of sea water that comes
on a tide. The tidal volume of Elkhorn Slough has
doubled since 1970. Increased tidal volume and current
velocity lead to a wider and deeper channel, which,
in turn, increases tidal volume.
The
full glossary of Slough Speak terms is here.
Land trusts have protected
2.3 million acres in California
Nobody
really knows how many land trusts there are in
California. The Land Trust Alliance, the national
network of local land trusts, lists 181 California
land trusts. California’s new land trust
council has a data base with 255 possible land
trusts. There may be more. Regardless of the exact
number, it is clear that they have protected a
lot of land. The LTA reports that 115 California
land trusts have protected 1.2 million acres of
land. When national conservation groups working
in California are included, the amount of protected
land rises to 2.3 million acres.
Leading land trusts, including the Elkhorn Slough
Foundation, have banded together to create the
California Council of Land Trusts – to provide
a voice in Sacramento for this powerful, but disparate,
movement. ESF Executive Director Mark Silberstein
worked as a member of the Steering Committee that
led to the creation of the CCLT earlier this year
and ESF is one of 68 Founding Members of the council.
This
ridgeline at the end of the North Slough runs along
Carneros Creek.
ESF has now protected 1300 acres along this ridge.
The
Council’s goals include increasing and diversifying
the financial resources for a broad range of conservation
needs, from acquisition and stewardship to education
and restoration. The Council will also be the land
trusts’ voice in Sacramento, where laws that
govern our work are made. Finally, the Council will
facilitate the invaluable sharing of information
among local groups.
It sometimes comes as a surprise to new ESF staff
members that we are considered one of the “big
dogs,” compared to most local land trusts.
Most local groups have just one or two staff members,
if that many, and often lack the kind of comprehensive
conservation plans ESF developed in 1999.
For these reasons we are often held up as a role
model, a role which feels a little strange since
we’re mostly aware, in our day to day work,
of how much more we need to do. We’re also
aware that we have learned from others, who were
our role models. All in all, our experience is that
it is a good thing to work together – in and
around Elkhorn Slough and across California and,
indeed, the entire country. And for that reason
we’re glad to have helped get CCLT going and
proud to be a founding member.
For more information on CCLT, visit their website.
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Who
we are,
what we do
The
Elkhorn Slough Foundation is a community-based
nonprofit founded in 1982 with the mission of
conserving and restoring Elkhorn Slough and
its watershed.
The Foundation has spearheaded innovative and
cutting-edge research, conservation, and educational
programs in Elkhorn Slough.
The Foundation currently owns and/or manages
3600
acres, the largest conservation holdings in
the Elkhorn watershed. Since its inception,
the Foundation has been directly involved in
the restoration of over 1000 acres of key habitats,
including tidal wetlands, coastal prairie, oak
woodlands, freshwater ponds, riparian corridors,
and chaparral.
The Foundation is a 501(c)3 non-profit under
the Internal Revenue Service Code and is the
only community-supported organization wholly
dedicated to conserving and protecting Elkhorn
Slough and its watershed. Seven hundred members
support the activities of the organization.
A fourteen-person board governs the Foundation.
The board represents a broad cross-section of
community interests including conservationists,
attorneys, educators, farmers, academics, business
people, scientists, and community volunteers.
Several board members have roots in the community
going back five generations.
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"Farming
and the environment can go hand in hand"
When
we talk about Elkhorn Slough as a “working
landscape,” we talk the talk and walk
the walk. Power lines cross ESF lands, railroad
tracks border them, and we encourage farming and
ranching on the properties we own and manage. ESF
leases over 300 acres for farming and ranching.
We do it because we are committed to agriculture
and a healthy environment – and because we
believe the two go hand in hand in Elkhorn Slough.
The latest evidence of this commitment is at the
Brothers ranch where, this spring, ESF has leased
certified organic land to Martinez Farms, a local,
family-run operation.
When we acquired the 350-acre property in 2002,
more than 70 acres had been cultivated, much of
it on steep slopes that generated the high levels
of soil erosion identified in our Watershed Conservation
Plan as a major threat to the health of the slough.
The property is one of five that run along the ridge
south of Carneros Creek, which is the source of
70% of Elkhorn Slough’s fresh water. ESF has
protected the bulk of this three-mile ridge during
the past five years.
Organic crops are being grown on the Brothers property.
ESF laid out the new farm fields to reduce soil
erosion.
In
order to both farm and protect Elkhorn Slough, we
first had to reduce what is called the farmland
footprint – the shape and amount of land under
cultivation. Our goal is to continue farming land
where the slope is low enough to make soil erosion
manageable, though the use of sediment basins, drainage
channels, and other techniques we’ve used on
our other leased lands. At the Brothers property,
our land staff carefully mapped out the slope and
marked out a new farm footprint of 21 acres.
We then allowed the land to remain fallow for three
years, so that it could be certified for organic
farming. “We wanted to add organic farming
to the mix,” says ESF Executive Director Mark
Silberstein. “Our goal is to mimic the farming
patterns of the watershed, so that we can experiment
and serve as a model.” A quarter of the watershed
is cultivated, with strawberries by far the dominant
crop. ESF currently leases out land for conventional
strawberry farming, perennial herbs, and holistic
grazing. The Martinez family will grow organic strawberries
and vegetables such as beans, tomatoes, peas, and
peppers.
ESF Farmland Manager John Kenney is enthusiastic
about the new operation. John worked as a farm manager
for ten years, and he’s the person who mapped
out the new farmland footprint. For the past six
months he has taken photographs of the progress
being made: fields cleared, crops sowed, the first
touches of green. “It’s exciting,”
he says, smiling, looking at the pictures. A farmer
at heart, John is now working to show that viable
farming and a healthy environment can go hand in
hand.
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Stewardship
Circle donations
to approach $500,000
Three
years ago the Elkhorn Slough Foundation Board
of Directors created the Stewardship Circle
to support ESF’s growing land management
responsibilities. At the time ESF managed 2000
acres of land, but the Board knew that was going
to grow – and so would our responsibility
to care for the land. Today ESF owns or manages
3600 acres of land. During the past three years,
our land management budget has more than doubled.
A critical and vital part of this effort has
been more than $400,000 in donations from members
of the Stewardship Circle. In the past three
years, 84 members of the Stewardship Circle
have each contributed $1000 or more. Last year,
seven members made gifts of $10,000 or more,
which allowed ESF to add a much needed third
member to our land staff.
In the next issue of Tidal Exchange we will
honor members who have given in the past year.
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We
celebrate at the Monterey Bay Aquarium
Over
200 new members are receiving this issue of Tidal
Exchange – and we welcome you! This spring
ESF launched a campaign to increase its membership
to 1000 by the end of the year. During the past
three months more than 200 new members have joined
in our effort to protect Elkhorn Slough –
bringing us to within 100 members of achieving
our goal. “It’s gratifying,” says
ESF Development Director, Stephen Slade, “to
have so many people care about protecting this
special place.”
Slade encourages current members to pass on the
names of those they think may be interesting in
joining the Foundation. ESF will send a copy of
a “special edition” newsletter containing
some of the best articles from Tidal Exchange
over the past couple of years. You can submit
names on our website or by mailing them to us
at PO Box 267, Moss Landing, CA 95039.
Benefits
of membership include our annual Spring Walk.
More
than 200 ESF members enjoyed themselves at our 23rd
Annual Celebration in June at the Monterey Bay Aquarium’s
new Ocean’s Edge Exhibit. Our thanks to the
Aquarium for their donation of the space and for
many special touches, like leaving the new aviary
open an extra hour so we could enjoy this small
recreation of the landscape we are protecting.
ESF presented its Heritage Award for extraordinary
contribution to the protection of the slough to
the Aquarium. Executive Director Julie Packard accepted
the award and pointed to the shared goals of the
Aquarium and ESF in protecting the rare and threatened
environments we cherish.
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Fall
Kayak Tours
Last
year’s kayak tour of the North Slough was so
much fun, we decided to make it another one of our
annual traditions, like our spring walk and our
summer celebration. This year we’ve scheduled
kayak tours on two Saturdays, September 24th and
October 1st, both from 2:30 p.m. to 5:30 p.m.
As
we did last year, we’ve teamed up with Monterey
Bay Kayak and the Kayak Connection to rent kayaks
at a discount for ESF Members ($25 per person).
ESF and kayak shop staffers will be on hand to answer
questions about kayaking and the natural wonders
you will see.
To reserve your space, please call our office at
(831) 728-5939.
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Table
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Tidal
Exchange is
written and edited by ESF staff.
To receive a copy or to send one to a friend, email
us.
Board
of Directors
Diane Cooley
Steve Dennis
Bill Eggleston
Dick Hammond
Candace Ingram
Paul Irwin
Richard Morris
Dick Nutter
Anne Olsen
Jerry Patrick
Wil Smith
Jack Taylor
Jim Van Houten
John Warriner
Steve Webster
Lydia Villarreal
ESF
Staff
Mark Silberstein, Executive Director
Kris Beall, Administrative Director
Stephen Slade, Director of Communications & Development
Kim Hayes, Land Manager
John Kenney, Farmland Manager
Ken Collins, Assistant Land Steward
Kevin Contreras, Land Acquisition Coordinator
Greg Hofmann, Communications & Development
Susan Burgess, Bookstore Manager
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