The primary current state actions on atrazine concern Total Maximum Daily Load Allocations ("TMDLs") under the Clean Water Act. A TMDL calculates the maximum amount of a pollutant that a waterbody can receive from all point and nonpoint sources and still meet state water quality standards, and contains an allocation of that amount to the pollutant's sources. The TMDL must include a margin of safety to ensure that the waterbody can be used for the state's designated sources. The calculation must also account for seasonal variability. Both the TMDL and overall water quality standards programs are established by Section 303 of the federal Clean Water Act, 33 U.S.C. § 1313. The primary source of atrazine into water bodies is surface runoff after application to fields.
Calculation of atrazine TMDLs at this point in time is complicated by two factors. First, there are no final EPA water quality criteria for atrazine. State water quality standards, from which TMDLs are calculated, are ordinarily based on EPA water quality criteria. Second, EPA has proposed to withdraw its current rules governing the calculation of TMDLs. EPA's current TMDL rules are extremely controversial, and the TMDL process is the subject of considerable litigation.
CRE is aware of six TMDLs for atrazine that EPA has approved. One is in Iowa; four are in Kansas; and one is in Louisiana.
CRE Position on Atrazine TMDLs
There are no final EPA water quality criteria for atrazine. EPA's current TMDL program and rules are the subject of widespread litigation. EPA has proposed to change its current TMDL rules. Under these circumstances, CRE recommends that to the extent, legally possible, stated should defer establishing TMDL for atrazine until the current legal and scientific uncertainties are clarified. CRE believes that EPA should coordinate its FIFRA/FQPA review for atrazine with EPA's TMDLS standard-setting process to ensure Government-wide consistency in the regulation of atrazine. Inconsistent standards would cause significant implementation, compliance and enforcement problems.