[8] The Murderkill River is tidally influenced from its mouth upstream to just past Frederica,[3] and is considered by the U.S. Army Corps of Engineers to be navigable for the lower 10 miles (16 km) of its course.

[9] According to 2002 data from the United States Environmental Protection Agency, 55% of the area of the Murderkill River's watershed is occupied by agricultural uses; 17% is forested; 14% is urban; 9% is wetland; and 2% is water.

[3] One description of the river's naming was recorded in 1945 by George R. Stewart, but is now considered to be a folk tale:[10] ...remembering how they had been served at the Whore-Kill, they went some ten or twelve miles higher, where they landed again and traded with the Indians, trusting the Indians to come onto their stores ashore, and likewise aboard their sloop drinking and debauching with the Indians until they were at last barbarously murdered, and so that place was christened with their blood and to this day is called the Murderer-Kill, that is, Murderers Creek.

"[10] The term "kill" is used in areas of Dutch influence in the Netherlands' former North American colony of New Netherland, primarily the Hudson and Delaware Valleys to describe a creek, river, tidal inlet, strait, or arm of the, sea such as Bronx Kill in New York and Schuylkill River in Pennsylvania.

[12] Also, in New York there is Muddy Kill, with a clear connection to the older Dutch name.