Gravel to Gravel: Combating Elodea to protect Alaska's salmon habitats

Alaskan waterways, and the salmon that call them home, face a range of threats. Not least of which is Elodea, Alaska’s first known invasive aquatic plant. Once established, these plants spread like an underwater plague. With rapid growth and easy spread, this invasive negatively impacts the quality of stream habitats for juvenile salmon, poses risks to the health of riverscapes and threatens population-level impacts on salmon returns. Early detection and rapid response to invasive species, as well as established invasive species inventories, are critical to reducing these risks and ensuring the resiliency of our aquatic ecosystems. The BLM’s Gravel to Gravel Keystone Initiative aims to do just that.  

Elodea, also known as waterweed and Canadian pondweed, is a hardy, fast-growing aquatic plant that is well suited to life in the cold, slow-moving waters of our state. While it is unclear exactly how Elodea was first introduced in Alaska, experts have speculated that it likely took hold in the state after well-meaning locals emptied aquariums into nearby bodies of water. Unfortunately, the contents of their tanks not only survived the eviction but went on to thrive in their new home. And it didn’t take long for the plant to spread out and get comfortable. 

According to the National Park Service, Elodea was first discovered growing in Eyak Lake in Cordova, Alaska, in 1982. Due to the still emerging field of research surrounding invasive aquatic plants in the ‘80s and ‘90s, it wasn’t until 2010 when the US Forest Service discovered the plant in the Chena River while surveying. From there, Alaska’s ~200,000 floatplane destinations run the risk of higher potential infestation of elodea, per the United States Geological Survey (USGS). A single 2-inch stem is all it takes for Elodea to establish itself in a new area, often after being transported by outboard motors on boats and the rudders of floatplanes.  

Once it finds it has room to stretch its roots, the plant has the potential to form dense stands that pack a one-two punch of habitat destruction. In these cases, elodea grows together so tightly that it blocks sunlight from traveling through the water. Without the necessary UV rays reaching them, less aggressive native species risk being choked out and Elodea threatens to establish a monoculture. But that is not all, the characteristic density of Elodea stands is often enough slow water flow and mixing rate in salmon streams. This allows for smaller sediment to settle out and cover the gravel required for salmon spawning.

What’s more, the plant follows a pattern of rapid growth and die off, leading to an excess of decomposing vegetation. All that decay rapidly consumes the oxygen in the water, leaving little for salmon and other aquatic organisms. Elodea is not a kind roommate; often leaving its cohabitants struggling to survive, both in and out of the water.  Unfortunately, salmon are among the aquatic animals negatively impacted by the presence of Elodea, which can restrict their access to gravel. Gravel on streambeds provides the nesting habitat required by salmon to lay their eggs. But when female salmon are unable to reach the gravel below elodea stands, populations take a hit.  

Salmon are crucial to Alaska’s ecosystems and the people who call them home. They, along with other traditional foods, have been vital to the cultures and survival of the state’s more than 100 Tribes. These first inhabitants have stewarded the region’s lands and set up fish camps in its watersheds for generations. But historic population declines of Pacific salmon in recent years have led to subsistence salmon fishing closures, empty smokehouses, and food insecurity for people who have relied on the subsistence use of salmon for more than 10,000 years. 

In recent consultations, congressional field hearings, and other forums, Department of the Interior leaders heard directly from Alaska Native Tribes and subsistence users about these ecosystem changes, their impacts on communities and cultures, and the need for immediate and lasting “gravel to gravel” action by the federal government – including the monitoring and control of invasive aquatic plants such as Elodea.

To answer these calls, the Department of the Interior — coordinated through the U.S. Fish and Wildlife Service and Bureau of Land Management — has partnered with Tribes, Indigenous leaders, the State of Alaska, other agencies, and community partners to launch the Gravel to Gravel Keystone Initiative. Using funding from President Biden’s Bipartisan Infrastructure Law, federal agencies, Tribes, and others will work together to build a strong foundation for co-stewardship, where Indigenous Knowledge and western science come together in the support of resilient ecosystems and communities.   

Under this initiative, the BLM is working to improve the resilience of ecosystems and salmon in Alaska’s Yukon, Kuskokwim and Norton Sound region. Beginning in 2024, the BLM’s partnership with the Fairbanks Soil and Water Conservation District will be expanded to include an invasive species inventory with the possibility of some high-priority control measures within several Wild and Scenic River units if Elodea is detected. Implemented in partnership with the State of Alaska and Tribes under the Good Neighbor Authority beginning in 2024, this project received an initial $1M allocation with similar funding levels from the Inflation Reduction Act (IRA) and Bipartisan Infrastructure Law (BIL) expected annually. 

Field offices across BLM Alaska are hard at work promoting healthy waterways and fighting invasive species. In previous years, the Eastern Interior Field Office partially funded Elodea eradication efforts in partnership with the Fairbanks Soil and Water Conservation District, an intensive multi-year process requiring herbicide application and frequent follow-up surveys and applications. Staff at BLM Alaska’s Central Yukon Field Office conduct annual searches for Elodea in presumed high-risk waterbodies, and/or in conjunction with other field work.  Additionally, a component of an agreement with Alaska Department of Fish and Game includes their staff searching for elodea in conjunction with inventory and monitoring activities conducted at BLM managed lakes across the field office. 

But we can’t do it alone! Our streams rely on the public, as well, to do your part to prevent the spread of invasives. The U.S. Fish and Wildlife Service encourages boaters to “Clean, Drain, Dry… After every waterbody, every time.” Prior to leaving water access, clean visible aquatic plants, animals and mud from all equipment. Next, rinse equipment and boat hulls with high pressure hot water, and interior compartments of boats with low pressure hot water. Then flush the motor with hot water for two minutes and drain motor, bilge, livewell, and other water containing devices. Finally, dry all equipment and water vehicles for at least five days or wipe with a towel before reuse.

The BLM’s rigorous training program, public data portal, and data analysis tools will empower stakeholders across the region and help shape strategic investments in restoration. We're also seeking enhanced funding for Alaska Native Tribes and ANCSA corporations through federal grants that specifically focus on Assessment, Inventory and Monitoring projects in areas that are frequently disturbed and have limited resources. The BLM is doing what we can where we can with the provided funding to make a positive and significant impact for the communities and ecosystems of the Yukon, Kuskokwim, and Norton Sound region. Together, we can work to slow the spread of Elodea and other invasives, protecting salmon populations for generations to come.