The Mississippi River below Lock and Dam No. 2 is the stretch of the Mississippi River that falls between the Hastings Dam (also known as Lock and Dam No. 2) and the entrance of the St. Croix River. It is part of the USACE's 9-Foot Channel Navigation Project and the Mississippi National River and Recreation Area. The Hastings Wastewater Treatment Facility discharges into this section of the Mississippi River. The monitoring sites in this section of the river were used for special studies and also to monitor the effects of the Hastings Wastewater Treatment Facility on the Mississippi River. Sample collection was limited to the open water (ice-free) season.The Mississippi River is one of the world's largest rivers, flowing over 2,300 miles through the center of the United States. It begins at Lake Itasca in northern Minnesota and ends at the Gulf of Mexico, where pollutants carried by the river contribute to the Gulf's Dead Zone. Millions of people rely on the Mississippi River as a source of drinking water, and the river is also an important waterway for shipment of commodities. The Mississippi River watershed is the 4th largest in the world at about 1.2 million square miles. The section of the watershed in and upstream of the Twin Cities Metropolitan Area has a mix of several types of land including forests, wetlands, agriculture, and developed areas.