As winters heat up due to climate change, a new study cites that pollution which occurs as a result of most agricultural methods will begin to rise across almost half of the country, according to Gizmodo. The research explains that chemicals from cow manure and fertilizer, such as nitrogen and phosphorus, are polluting groundwater, rivers, and lakes.

“The idea of winter nutrient pollution is new, because it’s a relatively recent impact of climate change with the potential to cause significant problems for people and the environment,” Carol Adair, a University of Vermont researcher and co-author of the report, said in a statement.

The pollution has also been associated with contaminated water, killing fish and other sea life as well as creating toxic algae in bodies of water. Before climate change, the chemicals remained in the soil until the weather warmed up in the spring.

In addition, when the temperature increases, it is more common for there to be rain which can cause runoff to seep into the soil, according to Grist. This can cause algae to bloom and more nitrogen to be created and leak into groundwater.

Researchers also say that more rain and snow occurrences will raise the level of nitrogen and phosphorus across 40 percent of the United States. Three years ago, the Mississippi River flooded after snow there turned into big downpours, which caused sediment to seep into the Gulf of Mexico. This led to the death of some of the biggest fish and other marine life in the sea.

Meteorologists are now predicting that this upcoming winter will be hotter than usual. This could make year-end temperatures three degrees higher than normal across large swaths of the middle of the country.

Scientists say they do not yet know exactly how much pollution has occurred in recent years when states that normally receive snow have had warmer winters. More research is needed regarding water quality.

“We hope this study is a wake-up call for government agencies and researchers, because it reveals that 40 percent of the U.S. is producing winter pollution—but no one is tracking exactly how much, where it’s going, or the impacts on water quality and ecosystems,” Adair said, according to the Gund Institute for Environment.