Revegetation of Hydroelectric Reservoir Shorelines to Mitigate Dust and Improve Human Health

Background/Question/Methods

The water storing reservoirs created by large hydroelectric dams pose significant environmental, social, and health-related challenges in Canada, and across the world. Reservoir shoreline erosion is a major issue, and research related to effective reservoir erosion control techniques is lacking. The Williston Reservoir, located in northern British Columbia (BC), is an acute example, as its sand beaches become exposed each spring due to dam operations and are the source of large-scale dust storms. These dust storms pose a health risk to the local indigenous community and dust mitigation is a top priority for Tsay Keh Dene Nation and BC Hydro. This study examined what native and agronomic graminoid and legume species can be used at scale to improve erosion and dust control on the beaches of the Williston Reservoir. Greenhouse trials were conducted to identify candidate plant species by assessing germination and emergence rates, plant and root biomasses, and root characteristics. Based on the results of the growth trials, 10 plant species were then tested on the beaches of the Williston Reservoir. Stratified field plots, 2 m x 2 m in size, were seeded on two different beaches to investigate plant survival, percent cover, density, and shoot/root biomasses.

Results/Conclusions

Our greenhouse experiments clearly indicated that agronomic species such as Avena sativa, Secale cereale, Hordeum vulgare, and Trifolium pratense were strong candidates for field trials due to their emergence and growth rates, and combined root and shoot biomass production. Several native graminoid species were also selected to include in field trials due to their growth and biomass results, including Elymus trachycaulus, Elymus lanceolatus, Poa secunda ssp. sandbergii, Festuca saximontana, and Poa palustris. There were clear differences between selected and rejected species in emergence rates and biomass production over the 7-week growth period. Field trials found A. sativa and S. cereale to be the best performing agronomic species, with the quickest emergence rates, highest densities, best survival, and most biomass produced. E. lanceolatus and P. secunda ssp. sandbergii were found to be the best performing native species, but the results clearly show that native species should be strategically used in higher elevation zones of the beaches due to overall performance and seed cost. We plan to continue monitoring the seeded plots in 2023, in addition to testing different fertilizer and compost treatments with the goal of developing scalable methods for boosting soil nutrient and organic matter levels on select beaches.