Elwha Watershed Information Resource

Researchers are currently studying the quality of lake sediments behind the two dams on the Elwha River to see if they will support native plants and determining the best methods to speed recovery of native vegetation. The focus of this part of the restoration effort includes:

Olympic National Park employees & volunteers collecting sediment from the Lake Mills reservoir for experimental plots. Kerri Cook, University of California Davis

 

• Sediment control (sediment characteristics and stabilization);
• Revegetation through plantings and seed transfer (air, water, and sediments); and
• Inventory and control of invasive plant species.

Individual project descriptions are listed below.

Assessment of Mycoengineering Technology
Stabilization of Reservoir Sediments
Seed Source: Lake Mills Submerged Seedbank
Seed Sources: Hydrochory in the Elwha River
Restoring Ecosystem Processes: Riparian Species Diversity and Invasion
National Park Service: Current State of Restoration Planning and Implementation

Assessment of Mycoengineering Technology

Research Question: Will "mycotechnology" (mycorrhizal inoculation, burlap sacks with wood chips and saprophytic fungi) improve soil structure and fertility of exposed sediments, allowing more rapid plant colonization?

Project Description: The purpose of this research is to quantify the effects of mycorrhizal and saprophytic restoration treatments by monitoring experimental plots for runoff, infiltration, erosion, and biomass production over 19 months beginning in 2005. In April 2007, destructive sampling of native plant species growing in existing plots along the shore of Lake Mills will provide final root to shoot ratios, as well as the percent mycorrhizal colonization differences between treatments. Final results will be analyzed to indicate the relative success of each treatment in enhancing plant growth and sediment stabilization. The results of this study can be used to provide treatment recommendations for the Olympic National Park’s Glines Canyon Dam – Lake Mills Reservoir Revegetation Plan.

Methods: In situ experiment measuring runoff, infiltration, erosion, soil strength, biomass production, and soil organic content (installed on Boulder Creek delta, Lake Mills, 2005).

Results: Data is currently being analyzed.

Collaborators:

• Kerri Cook, Principal Investigator, Master of Science Thesis, Biological Systems Engineering, University of California, Davis
• Wesley Wallender, University of California, Davis Professor in Hydrologic Science and Engineering
• Caroline Bledsoe, University of California, Davis Professor in Land, Air, and Water Resources and Mycology
• Greg Pasternack, University of California, Davis Professor in Hydrologic Science and Land, Air, and Water
• Steve Acker, Supervisory Botanist and Olympic National Park Liaison

Stabilization of Reservoir Sediments

Research Question: How can the 17.8 million cubic yards of sediment behind the Elwha Dam and Glines Canyon Dam be stabilized to prevent massive erosion?

Project Description: The purpose of this research is to prevent massive erosion during and after dam removal.

Methods:

• Laboratory study of erosivity with mulch, soil amendments, and plants tested under two water flow rates.
• Field study of soil ecosystem development on glacial lake sediments in the Elwha area.

Results: Mulch and soil amendments were successful in slowing erosion in the short term. Old glacial lake terraces may be useful in predicting soil development and vegetation growth along the exposed reservoir sediments.

Collaborators:

• Ellen Mussman, University of Washington
• Darlene Zabowski, University of Washington

Seed Source: Lake Mills Submerged Seedbank

Research Question: Do the sediments under Lake Mills contain a persistent, spatially variable seedbank that would provide an in situ source of plants for the restoration of newly exposed sediments?

Project Description: This project researched the submerged seedbanks under Lake Mills to determine if seeds found can germinate successfully in Lake Mills’ sediments.

Methods: Placed 91 samples of sediment from Lake Mills in the greenhouse for 5 months and allowed viable seeds from the samples to germinate and grow into identifiable plants.

Results: The research suggests that there are surprisingly few germinants in Lake Mills and that there is a negative relationship between number of germinants and lake depth.

Collaborators:

• Joshua Chenoweth, University of Washington
• Kern Ewing, University of Washington

Seed Sources: Hydrochory in the Elwha River

Research Question: Will hydrochory (water-borne seed dispersal) contribute to revegetation in flooded areas?

Description: This project is trying to determine if hydrochory can contribute to revegetation in flooded areas along the Elwha River, and also if the Glines Canyon Dam currently limits hydrochory.

Methods:

• Sample water-borne seeds using drift nets.
• 6 nets per transect at two levels in the water column (surface and subsurface).
• Nets set up for 3 hours per sample above and below Glines Canyon Dam.
• Samples collected 3 times in July and August, 2005.
• Seeds germinated in the Eastern Washington University greenhouse.

Results: Significant decreases in seed abundance and species richness were found below Glines Canyon Dam, indicating Glines Canyon Dam reduces hydrochory.

Collaborators:

• Rebecca Brown, Eastern Washington University
• Malcolm Havis, Eastern Washington University

Restoring Ecosystem Processes: Riparian Species Diversity and Invasion

Research Questions: Do dams influence native species diversity or exotic species invasion (altered flood dispersal and disturbance)? Will exotic species spread upstream in the Elwha watershed when the dam is removed? Will exotic species invasion limit the success of restoration? How does exotic species invasion vary above and below the dam?

Project Description: This project is researching riparian vegetation composition and diversity along the Elwha River to see how dams influence plant species diversity and non-native species invasion. Data collected will help to predict how invasive plants will spread following dam removal and if they will affect restoration of plant communities on exposed sediments when the dams are removed.

Methods:

• 2005 vegetation survey
• 125 plots (100 square meters each) along 15 transects
  • 41 below Elwha Dam
  • 39 above Glines Canyon Dam
  • 37 between the dams
  • 4 on the delta of Lake Mills
• Soil seed bank samples collected at each plot

Results: This study found that native species richness is lower below the dams, while non-native plant species richness is higher below the dams.

The following exotic species were found:

• Buttercup (Ranunculus repens)
• Clover (Trifolium repens)
• Curly dock (Rumex crispus)
• Dandelion (Taraxacum officinale)
• Dovefoot geranium (Geranium molle)
• English plantain (Plantago lanceolata)
• Foxglove (Digitalis purpurea)
• Herb Robert (Geranium robertianum)
• Orchard grass (Dactylis glomerata)
• Scotch broom (Cytisus scoparius)
• Sheep sorrel (Rumex acetosella)
• Stinging nettle (Urtica dioica)
• Velvet grass (Holcus lanatus)

See the Image Gallery for pictures of these species.

Collaborators:

• Rebecca Brown, Eastern Washington University

National Park Service: Current State of Restoration Planning and Implementation

Research Question: Where are invasive exotic plants species located in the Elwha watershed?

Project Description: Researchers at the National Park Service are currently mapping invasive exotic plants in the Elwha watershed and are working to define restoration targets for revegetation using a Lake Mills delta inventory done in 2002 and a riparian and upland forest composition assessment done in 2003. They are also developing a native seed collection and working with partners to propagate native plants to be used at restoration sites.

Methods:

• Lake Mills Delta Inventory (P. Cereghino, W. McClure, and R. Olson 2002).
• Riparian and Upland Forest Composition (S. A. Acker, R. W. Olson, Jr., and M. M. Bivin 2003).
• Invasive Species: Mapping selected invasive exotic plants in the Elwha watershed (R. W. Olson, Jr., K. E. Mitchell, and T. B. Murphy 2001).
• Divided restoration area into seven habitat types.
• Identified extent, revegetation methods, and other treatments by habitat.

Collaborators:

• Steve Acker and others, National Park Service