Go with the Flow
In Central Oregon, the BLM is helping historic marshlands return to their natural roots.
story & photos by Kevin Abel
Back in the 1940s, Oregon's Wood River Wetlands were converted from marshes to farmlands. Good for growing crops? Absolutely. But not particularly sustainable.
Today we now know that converting this type of land to agricultural use often requires draining water. A lot of water. And as water levels are reduced and farming introduced, the natural character of the soil may become depleted over time. And if it does? The land needs help.
Enter the BLM
2014 marks the 20th anniversary of the BLM's support of this historic river delta. And by all accounts, every effort to repair this marsh north of Agency Lake and return the land back to local flowers and fish is going quite, shall we say…swimmingly.
But that's not to say progress hasn't been without its challenges.
Raise the Land
By the time the BLM acquired this area in 1994, the wetlands had significantly subsided (read: "sunk") some two to five feet – a level approximately six feet below the water surface elevation of nearby Agency Lake. Given this drop, the BLM couldn't just "turn on the faucet" by allowing the nearby lake waters to flood this emerging marsh without drastically altering the landscape. Changes would have occurred too quickly for the environment.
So the idea is to raise the Wood River Wetlands at a more natural pace – a progress of around one inch per year – until the wetland surface is elevated enough to meet the water levels from Agency Lake. The BLM has already begun its process of rebuilding through a number of scientific techniques that include growing and maintaining local vegetation. And in the meantime, BLM hydrologist Andy Hamilton points out that "a system of pumps, water control structures, ditches, and levees is required to manage this wetland."
But how can we test to make sure the BLM's techniques are working? How will we know our efforts are helping reverse the sinking in order to rebuild these wetlands?
The BLM has placed clay markers in the area to provide a visual baseline that will track annual growth. Local soil is measured yearly by "cryo-coring," a process of using liquid nitrogen to freeze soil core samples. This method is invaluable for measuring the amount of organic soil that accumulates over the top of the markers.
Hamilton says, "This method is good for extracting an intact soil core because it freezes a small section without disturbing the rest of the soil around it." (Plus it makes for a pretty cool photograph.)
The Long Haul
Long-term, the BLM's vision is to reverse the erosion that occurred at the Wood River Wetlands as a result of the original draining and farming of these native marshes.
"We think that if we could gain approximately two feet of soil over portions of the wetland, we could allow Agency Lake to flood and maintain the integrity of wetlands," says the BLM's Hamilton. He continues to point out that this progress would also allow for the re-introduction of threatened and endangered fish.
So by taking the long-term approach, the BLM will ensure this area will not stay sunk below the level of the nearby lake and thus become flooded before it's ready to return to its natural state. No doubt local plants and fish will be grateful.
Revitalization is a part of nature's continual ebb and flow. And a careful approach to this process at the Wood River Wetlands will ensure long-term success. It may not be rushed, but that's okay. For now these wetlands seem very happy to go with the flow.