Climate change is altering the flow of the Missouri River, the nation’s longest, causing increased streamflow in some parts and decreased flow in others, according to a new report.
The report, published by the U.S. Geological Survey, looked at streamflow data from 227 streamgages — tools that estimate water flow — in the Missouri River from over the past 50 years. According to the study, almost half of the streamgages showed either increasing or decreasing trends in flow since 1960. In the eastern part of the river’s watershed, which includes parts of North and South Dakota and Iowa, streamflows have increased, while in western states like Montana and Wyoming, streamflow has decreased.
Montana farmer Rocky Norby told the LA Times that streamflows got so low on his farm last year that he was forced to spend more than $10,000 to unclog the sand from his irrigation system. Norby’s farm depends heavily on irrigation — if he wasn’t able to irrigate his crops, he said his production would drop significantly.
“Every year it gets worse,” he said. “There’s not enough water to get through our pumps.”
The Missouri River provides “critical water resources” to agriculture and energy and also serves as a source of drinking water for some towns and cities along its path, USGS hydrologist Parker Norton said in a statement.
“Understanding streamflow throughout the watershed can help guide management of these critical water resources,” he said.
Climate change is likely playing a role in the river’s changes in streamflow, Mark Anderson, one of the report’s authors, told the LA Times. Dennis Todey, a climatologist at South Dakota University, explained further, telling the paper that changes in precipitation are likely what’s partially to blame for the changes in streamflow.
“If you look at Wyoming and Montana, you see a decline in precipitation, but farther east into the Dakotas, there is a well-documented increase in precipitation,” Todey said. “More water, more opportunities for flooding.”
The problems the Missouri River is facing could be reflected in rivers worldwide as the earth continues to warm. In 2007, a study published in Frontiers in Ecology and the Environment predicted that many rivers that are impacted by dams or other development will need major changes in management to make them more resilient to climate change.
“As a result of damming and development, major rivers worldwide have experienced dramatic changes in flow, reducing their natural ability to adjust to and absorb disturbances,” lead author of the study Margaret Palmer said. “Given expected changes in global climate and water needs, this could lead to serious problems for both ecosystems and people.”