The letter sent to Secretary Grumbles outlines the plain fact that exposed soil leads directly to water pollution when dirt from construction sites runs off into local streams and onward toward larger rivers and ultimately the Bay. This cascade of mud brings not just water-clouding particles into streams that can choke out plant life but also high levels of nitrogen and phosphorus - the two leading culprits behind failing ecosystems in our waterways. Construction is in fact one of the highest contributors of these types of pollution.