environment; total maximum
daily loads
DP |
Committee on Environment |
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DPA |
Committee on Natural Resources & Agriculture |
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DPA |
Caucus and COW |
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DPA |
Third Read |
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X |
As Passed the House |
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HB 2097 modifies ARS section 49-234 of the Total Maximum Daily Load (TMDL) program in DEQ, to combine the processes of determining allocations among the contributing sources and determining the total amount of each pollutant. Currently they are two separate processes. The TMDL program is designed to help an impaired stream or lake meet its water quality standards and support its designated uses, such as protection of aquatic life, drinking water and fish consumption. A TMDL is defined in ARS section 49-231 as an estimation of the total amount of a pollutant from all sources that may be added to a body of water without causing it to exceed applicable surface water quality standards. The program is part of the federal Clean Water Act.
The TMDL program was added by Laws 2000, Chapter 162. Section 303(d) of the federal Clean Water Act established authority for the TMDL program and guides states on how to develop these plans for waters that do not meet water quality standards. Every two years, each state submits to EPA a list of impaired waters (the 303 (d) List) and a schedule to establish TMDLs. EPA reviews and approves the 303 (d) list and schedule, and reviews individual state-submitted TMDLs. If EPA disapproves a list or a TMDL, EPA is required to establish the lists and/or TMDLs itself.
The calculation of TMDL accounts for all sources of the pollutant in question including point sources (sewage treatment plant discharge), nonpoint sources (such as runoff from fields, streets, range, or forest land) and natural sources (such as runoff from undisturbed lands). TMDLs may address individual pollutants or groups of pollutants, and they must identify the linkage between the following issues: 1.) Identification of the impairment occurring in the waterbody, 2.) Cause of the impairment, and 3.) The actions that need to be taken to bring the waterbody into compliance with the standards.
A TMDL is calculated based on estimated (modeled) or measured quantities of metals, nutrients or other pollutants discharged to a waterbody at current and historical flows.