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Climate Change (Rising Sea Levels) Could Be Bad News For Lower Columbia Restoration
Posted on Friday, October 23, 2015 (PST)

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 downstream.

 

“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 http://www.nwcouncil.org/media/7149605/f5.pdf

 

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 said.

 

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 mainstem river.

 

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 estuary.

 

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 development.

 

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.

 

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