Photo courtesy of the Chesapeake Bay Program
This page serves as an information hub for all current MDE guidance, policies, ongoing work, and resources for cold water protection.
Cold water streams in Maryland are a vital resource for aquatic communities that rely on lower temperatures to thrive. Identifying and protecting the thermal regime of these stream environments is crucial for supporting vulnerable cold water species. These species include Maryland’s native brook trout, recreationally important populations of rainbow trout and brown trout, and two cold water obligate benthic macroinvertebrates (Tallaperla and Sweltsa). The Strategy for Protecting and Restoring the Chesapeake Bay Watershed, Executive Order 13508, further identifies the brook trout as a key indicator species for Maryland’s waters, reflecting overall stream habitat health and holding great ecological, commercial, and recreational significance.
Maryland designates and protects cold water streams under the federal Clean Water Act, identifying them as Use Class III (nontidal cold water use), or Use Class IV (trout-stocking waters). Growing concerns around climate change and warming temperatures highlights the importance of protecting these valuable cold water resources in Maryland. Elevated water temperatures due to climate change will limit the available cold water habitat for dependent species, threatening their populations. Increased development in the watersheds of cold water streams or best management practices (BMPs) lacking cold water protections can compound the problem, contributing to higher influxes of warm temperature stormwater runoff into vulnerable cold water streams. Water quality standards in conjunction with strategies to best manage and mitigate high temperatures are therefore critical to the survival and health of cold water communities.