Scientists have observed that the climatic factors that affect water quality are already changing, and they realize the implications of those changes for two primary areas: drinking-water and wastewater infrastructure, and aquatic life. However, the science community remains hopeful that resource managers can anticipate and adapt to these effects successfully.

"There are a lot of climate variables that affect water quality," explained Joel Scheraga, director of Global Change Research at the U.S. Environmental Protection Agency, who spoke on May 8 at the National Summit on Coping with Climate Change. "As the earth is warming, we are seeing an intensification of the hydrologic cycle, so the amount, timing and distribution of rainfall around the country are changing.

"That will affect water quality," he continued. "With the intensification of the hydrologic cycle, we are also seeing more extreme rainfall events, as well as rising sea levels, which have their own impacts on water quality."

But not all regions of the United States are experiencing the same effects from these changes. "What’s going on in the Great Lakes is very different from what’s going on in the Southeast or California," Scheraga added. "As we think about anticipating and adapting, we must be sensitive to this regional texture. What it means is that the impacts on water quality in one part of the country will be very different than the impacts in another part."

The nation’s drinking-water and wastewater-treatment systems may be at risk, if proper precautions are not taken to counteract or compensate for flooding, rising sea levels and other climate-related trends. "If one does not consider climate change as we design and build these systems and invest billions of dollars, we may find that in 10 or 20 years the investment is not as effective as we expected it to be," Scheraga said.

Aquatic ecosystems also are highly sensitive to changes in climate. Warmer water temperatures, for example, can reduce dissolved oxygen concentrations, decrease water volume, and increase concentrations of nutrients and pollutants. “Warming waters may exceed the temperature thresholds for certain species, causing them to disappear, or lead to the invasion by exotic species that previously were not native to rivers and streams,” he added. Runoff and erosion caused by heavy rainfall can lead to a further decline in water quality.

"We have the ability to recognize that these changes in water quality are occurring today, and we can begin to respond now," Scheraga urged. "The way we can do this is by conducting assessments that provide valuable information to the water-resource managers about both potential impacts and adaptation options, which the policy makers then can choose from. We also can provide water-resource managers with decision-support tools to help them understand the implications of climate change for water quality and help them evaluate the effectiveness of different management practices."

Scheraga announced that the EPA recently released the new version of its “Basins” modeling system, a free, publicly available, online modeling tool used by regional, state and local agencies to perform watershed analyses. Other climate assessment and water-quality planning tools are also being developed.

"We cannot be cavalier about how easy it is to adapt," Scheraga cautioned. "We tend to think that since we’re such a wealthy and technologically advanced country, we can anticipate and adapt to climate change effectively."

The National Summit on Coping with Climate Change, May 8-10, was hosted by the School of Natural Resources and Environment on behalf of the University of Michigan. The summit is part of the Clinton Global Initiative, a non-partisan catalyst for action, established by former President Bill Clinton and the William J. Clinton Foundation for the purpose of bringing together global leaders to devise and implement innovative solutions to pressing world challenges.

By Claudia Capos

For more information, contact Cynthia Shaw at

cshaw@umich.edu or call 734-763-6605.