Total Maximum Daily Loads – Clean Water Act


The Total Maximum Daily Load (TMDL) program has the potential to affect adversely aggregates mining operations in at least two ways.

  1. Aggregates facilities that have proactively instituted no-discharge or recycled waste water systems may find their allowable permitted discharge limits allocated to other industrial sources that actively discharge into the same receiving stream as the aggregates operation.
  2. Aggregates operations that were one of the first industrial sources located along the receiving stream and are actively discharging may find their permitted discharge limits divided among newer sources locating along the same receiving stream in the future.



The TMDL program is a water-quality based pollution control program designed to maintain designated uses for water bodies throughout each state. A TMDL is a calculation of the maximum amount of a pollutant that a water body can receive and still achieve state or federal water-quality standards. The TMDL identifies the reductions needed to meet water-quality standards. It then allocates these reductions among the sources in the watershed.

The TMDL rule was initiated in section 303 (d) of the 1972 Clean Water Act. Section 303 (d) requires states to identify waters not meeting water-quality standards, set priorities for TMDL development and develop a TMDL for each pollutant for each listed water. Typical pollutants associated with aggregates mining include total suspended solids and total dissolved solids. A single water body may require multiple TMDLs to be developed. Many states are in the process of implementing the federal TMDL program. The EPA approves or disapproves the state’s submissions. If disapproved, EPA will act in lieu of the state.



  • It is critical that each aggregates mine site receive a fair and just pollutant allocation.
  • TMDL credits must be given to those facilities that institute proactive no-discharge, recycled waste water systems.
  • Those facilities’ unused allowable permitted discharge limits must be protected for future use by those facilities.
  • NSSGA supports a free-market system, similar to the existing air shed trading program of the Clean Air Act, that allows for trading or selling of TMDL credits with other sources in the same watershed.


Updated:  September 2012