"With the arrival of spring, many freshwater streams in the Chesapeake Bay region will experience spikes in salt levels — coming mostly from the salt used to treat roads during winter, still working its way toward streams with spring rains. And while efforts are underway across the region to reduce harmful salt in freshwater streams, research shows that salinity continues to rise. John Jackson, a senior research scientist at the Stroud Water Research Center in Pennsylvania, said rock salt is now part of the water cycle. And even where it doesn’t flow directly into streams, it seeps into the earth and reaches groundwater and aquifers. While plants and animals closer to Chesapeake Bay, especially in its more southerly reaches, have evolved to tolerate salty water, those in freshwater rivers and creeks have not. Any increase in salt can make it difficult for fish to regulate the salt in their body. For humans, salt can reach drinking water sources, contributing to heart and kidney diseases.…