Since the 1870s, 114,050 acres of land in the lower Columbia
River estuary have been converted to farm, industrial and urban uses, reducing
native habitat for fish and wildlife. The good news is that about half of that
is recoverable and could be restored.
Most of that territory is downstream of the
Longview/Portland corridor where much of the land has been paved over and,
according to the Lower Columbia Estuary Partnership, is “recovery-challenged.”
However, rising sea levels due to climate change may
inundate more lower-river lands and move the salt water estuary further
upstream, perhaps defeating many of the habitat recovery efforts, according to
Catherine Corbett, chief scientist at LCEP.
Speaking to the Northwest Power and Conservation Council’s
Fish and Wildlife Committee last week at its meeting in Vancouver, Wash.,
Corbett laid out the potential for habitat recovery in the lower river, but
then warned that today’s recovery projects may end up as “ecosystem museums” as
climate change could raise water levels and flood recovered lands, altering the
river even more.
“Things we do now may not be protective of species moving
forward,” she added.
Water temperatures in the Columbia River at Bonneville Dam
have warmed considerably since 1940 when the average August water temperature
was about 19.5 degrees C (67.1 degrees Fahrenheit). Temperatures rose to 21.7
degrees (71.06 degrees Fahrenheit) this August, but an early warming spike in
July hit 22.3 degrees (72.14 degrees Fahrenheit).
Salmon and steelhead prefer water in the 16 degree C (60.8
degrees Fahrenheit) range.
Tributaries of the Columbia River
have little influence on cooling the lower river, Corbett said.
The river temperature at a Camas/Washougal temperature gauge
is the same as the temperature at the Beaver Terminal near Clatskanie, 65 miles
“The tributaries have little influence on temperature in the
lower river, so the main driver (for temperature) in the lower river is
the water coming through Bonneville Dam,” she said. “We are not sure if the main tributaries downstream of Bonneville Dam
are cold enough to provide refuge for migrating fish.”
The LCEP presentation is available at the Council website at
Founded in 1995, LCEP’s mission is to protect and restore
ecosystems and enhance clean water in the lower Columbia River for current and
future generations of fish, wildlife and people, according to the nonprofit’s
website (http://www.estuarypartnership.org/). They have about a $4-5 million
budget to do this work, with about $3 million coming from the Bonneville Power
Administration’s Fish and Wildlife program, according to LCEP’s executive
director Debrah Marriott, who also spoke at the Council’s meeting last week.
As climate warms, conditions in the estuary will change.
There will be less habitat for cold water species that need cold water refuges,
such as salmon and steelhead.
Precipitation patterns will change – more will fall as rain and
snowpacks will be skimpier – all resulting in higher winter flows and lower
summer flows. As the sea level rises due to melting ice at the poles, habitat,
much of it restored to preindustrial levels, in the lower estuary will be
flooded and wetlands will move inland, Corbett predicted.
One way to get a head start on mitigating for climate change
is to begin studying and creating thermal refuges for anadromous fish, she
There are a few very small tributaries near the dam that do
provide cooling water and, to a certain extent, the ocean also
cools the lowest portion of the river, Corbett said.
LCEP received a grant from the Environmental Protection
Agency to assess the potential of thermal refuges for salmon and steelhead in
the Columbia River Gorge below Bonneville Dam.
It is studying conditions and water temperature at the
mouths of these small tributaries, such as Tanner, Eagle and McCord creeks, as
they enter the mainstem Columbia River. It is looking at the extent of the
tributaries’ plumes and recording the temperature differential with the
The question LCEP is trying to answer is “are conditions at
mouths sufficient to cue fish to use these tributaries as refuges?” according
to LCEP’s presentation.
As it fills missing data gaps in what we know about climate
change impacts on the lower river, LCEP’s next step is to integrate the impacts
of climate change into its restoration plans, even as it continues to guide
restoration efforts intended to lead to considerable improvements in the
LCEP completed a study in 2011 of how habitat has changed on
the lower Columbia River from Bonneville Dam to the river’s mouth since the
1870s, finding that about half of native habitat (114,050 acres) has been lost.
The habitat includes 70 percent of the vegetated tidal wetlands and 55 percent
of forested uplands that had been converted to agriculture, industry or urban
From this information, LCEP identified habitat prime for
restoration and protection across eight reaches of the Columbia River
downstream of Bonneville Dam, finding that 77,210 acres are to some degree
recoverable. However, landowners would have to be willing, under LCEP’s
guidance, to restore their property, often giving up its current land use.
An additional 68,231 acres, mostly in the Longview to
Portland corridor, have been converted over the years to what LCEP calls
“impervious surface.” These areas would be more difficult and expensive to
restore, but it’s an area where “native habitats are scarce but critically
important to providing refugia in migratory corridors as species make their way
up and down the lower river,” according to LCEP’s presentation.
LCEP goals for the recoverable areas are:
-- no net loss of habitats based on the study baseline,
which is 2009.
--recover 30 percent of historic priority habitat by 2030.
-- recover 40 percent by 2050.
By 2050, LCEP targets will recover 46 percent to 88 percent
of historic habitat, depending on river reach, but with an overall average of
60 percent recovered.
One of the Council’s emerging priorities in its 2014
Columbia River Basin Fish and Wildlife Program is to account for the potential
impacts of climate change on restoration projects.