Hydroelectric generation in North America is producing steadier river flows which benefit aquatic species, according to a new paper authored by UNBC Environmental Science Professor Dr. Stephen Déry.

Déry and his collaborators studied the phenomenon of hydropeaking, when water levels in managed rivers rise or fall sharply due to increases or decreases in electricity demand. Their paper, Vanishing weekly hydropeaking cycles in American and Canadian rivers, published in Nature Communications, details the decline of hydropeaking in recent years. 

“There is a very consistent, overall decreasing pattern in the index values we’ve formulated for hydropeaking in this study, and the pattern crosses various jurisdictions, watersheds, and power grid interconnections,” Déry says. “A reduction in ramping up and ramping down in river flows benefits aquatic species and improves their habitat.” 

Déry, along with researchers at the University of Calgary and the University of Victoria, looked at 100 years of data from 500 sites across Canada and the United States. They found instances of hydropeaking increasing in the mid-20th century and then decreasing in the 21st century. 

“The results suggest that hydroelectricity demand and generation is changing, with less reliance on hydropower to support peak demand during daytime and weekdays,” Déry says.

Other reasons that could be contributing to the decrease in hydropeaking, according to the researchers, are the addition of more wind and solar energy to the grid, improved regulatory oversight, an increasingly interconnected grid that helps balance out the load and lifestyle changes that have resulted in more even electrical demand.

The findings can help hydroelectric companies refine their operations to further reduce the impact on aquatic life.

“Hydroelectric companies are all keen to understand how their operations are evolving with the goal of reducing their impacts on the environment,” Déry says. “Recent reductions of the weekly hydropeaking cycle provide evidence that hydropower operations are indeed being modified to improve ecosystem health and well-being.”

Déry says UNBC’s location, its computational resources as well as its ability to facilitate relationships with research partners, industry and other stakeholders make it a great place to conduct this research. 

“UNBC is an ideal location to undertake such work given we are surrounded by abundant natural resources including pristine waterways as well as regulated systems,” Déry says. “We, therefore, have good examples of the range of regulation, from heavily dammed systems like the Nechako, Columbia and Peace rivers, and unregulated ones like the Stuart, Liard, and Thompson rivers.” 

This study looked at data between 1920-2019, and Déry says the next phase of the work will examine the impact the COVID-19 pandemic had on regulated bodies of water.  

“Our preliminary analyses suggest a substantial decline in 2020 of the weekly hydropeaking index values as electricity demand diminished during the pandemic,” Déry says. “As well, we will be assessing the seasonal variation in hydropeaking and overall extremes. We also hope at some point to directly correlate electricity production with weekly hydropeaking cycles.”