A warmer, wetter climate in the eastern United States could also boost pollution from cities and farms draining into rivers, lakes and streams, according to a new report, and federal rules may not be flexible enough to handle it.
Researchers at the Rand Corporation examined two watersheds-the Patuxent River in Maryland and the North Farm Creek tributary of the Illinois River-to explore how the EPA's water quality plans would hold up during the future uncertainty of climate change.
In both regions, the study found that EPA's proposed plans meet the agency's water quality goals in under current assumptions of the region's climate, but do not meet water quality goals under future scenarios.
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"What we were doing was thinking about future vulnerabilities," said Jordan Fischbach, a report author and co-director of Rand's Center for Water and Climate Resilience. "How might the amount of pollution change in these different futures. All the states whose waters feed into the Chesapeake Bay, they've set ambitious targets, can you do that?"
The Maryland case looked at rules governing urban stormwater runoff from parking lots and city streets. The Chesapeake Bay ecosystem and its bounty of native oysters, crabs and fish species, is still struggling despite decades of work by states and local governments to control runoff.
The Illinois example looked at agricultural runoff from farms, which flows downstream and ends up in the Mississippi River. In fact, freshwater flows of the Mississippi carry an overabundance of nitrogen and phosphorous, primarily from farms, into the Gulf of Mexico. Each year, this runoff plume creates a so-called "dead zone" of oxygen-starved water that kills bottom-dwelling marine life.
Estimates by the International Panel on Climate Change (IPCC) and the National Climate Assessment call for a wetter and warmer eastern United States.
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"The trend is wetter, but it ranges from drier to a whole lot wetter," said Robert Lempert, senior scientist and director of Rand's director of long-range policy and human condition.
"Whether its farmland or a parking lot, when you run it in a simulation model, you see that as you increase rainfall, you increase the pollutants deposited into a river or stream," Fischbach added.
This climate-juiced rainfall might double pollution levels by 2050, the researchers said.
Solutions include building more "green infrastructure" to treat runoff before it reaches the river. This includes things like using grass waterways to slow down runoff, leaving tillage from harvested crops on the ground so rainwater doesn't hit not bare soil and building parking lots with grass strips to help water soak into the ground.
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EPA officials in Washington say they're working on the problem of polluted runoff now and planning for what could happen in a wetter world of the future. The agency approved a new rule in August that strengthens the definition of high quality water, a rule that has been fiercely opposed by farm groups and Republicans in Congress.
"Maintaining high water quality is critical to supporting economic and community growth and sustainability," said the EPA statement to Discovery News. "Protecting high water quality also provides a margin of safety that will afford the water body increased resilience to potential future stressors, including climate change."