Originally titled the Federal Water Pollution Control Act, this law was first enacted in 1948, completely rewritten in 1972, and additionally amended by the Clean Water Act of 1977 and the Water Quality Act of 1987. The CWA is the primary federal law governing water pollution with the objective of restoring and maintaining chemical, physical, and biological integrity of US waters. The law targets point source and nonpoint source pollution, manages wastewater treatment, and protects wetlands. More information is available on the EPA website.
The total maximum daily load is the maximum amount of pollution a body of water can receive while still meeting water quality standards. TMDL is determined by adding the Waste Load Allocation (the existing/future pollution level) to the Load Allocation (estimated background pollution) added to the Margin of Safety (calculated uncertainty in meeting water quality standards). Evaluation of body of water’s TMDL includes analyzing watershed characterization, impairment status, data gaps and monitoring report, source assessment, load allocation, set targets, and implementation plans. The evaluation of TMDLs allow states to identify impaired bodies of water.
The water cycle is a long journey! After a rain or snow event, the water in your yard has two options: 1) flow into a storm drain or 2) soak into the ground. With option one, water flows off hard surfaces, such as driveways and parking lots, and runs into storm drains. Any residue on these surfaces is carried into the drain and deposited unfiltered in the river. With option two, rainwater or snowmelt leaches through the soil and eventually reaches an aquifer, a layer of permeable rock that contains the groundwater. Flowing through capillaries, the groundwater eventually reaches a surface water source and is discharged. If you live in the Big Sioux River watershed, your groundwater discharges in the Big Sioux River or one of its tributaries.