Scientists issue warning for protection of temporary waterways

On August 31 of this year, 17 international researchers including Irstea ecologist Thibault Datry published an open letter in the journal Science, warning the international community about an imminent decision by the US Environmental Protection Agency (US EPA) to exclude temporary waterways from the Clean Water Act.

Temporary waterways are rivers that are regularly dry for part of the year and make up more than half of the length of the global hydrographic network. Alternating between aquatic and terrestrial ecosystems, they are home to specific animal and plant communities that are vital in preserving biodiversity and limiting the impact of climate change. Seventeen international researchers including Irstea's Thibault Datry published an open letter in the journal Science to warn about the impact of the decision by the US Environmental Protection Agency on biodiversity and water quality and quantity.

As a result of climate change and increasing demands on water resources, temporary waterways could come to dominate the landscape in some parts of the world. They represent 59% of the total river length in the US and 50% worldwide.

Although the decision to include temporary waterways in the definition of Waters of the United States (WOTUS) in 2015 was welcomed, the American government is now backtracking and looking to reconsider the implementation of the decision and revoke legal protection for temporary waterways whose surface waters contribute flow to permanent navigable waters.

Several international researchers decided to raise the alarm by publishing an open letter in the journal Science that condemns this reconsideration and asks US EPA to uphold its 2015 decision and ratify the legal status and protection of these temporary waterways. This would provide temporary waterways in the United States with a level of protection similar to that found in other countries such as Australia. "Excluding them means running the risk of polluting these watercourses when they connect intermittently with the hydrographic network,” states Thibault Datry of Irstea, one of the letter's signatories. "This would also cause expensive and potentially irreversible damages," he adds.

However, recent international research has highlighted the numerous ecosystem services provided by these temporary navigable waterways, particularly in relation to water quality and drinking water supply, as well as in reducing toxic substances and preventing floods. The also provide habitats for a unique level of biodiversity and have an impact on the global carbon cycle.

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