CWA Methods Regulatory History

Federal Register notices and related documents for approved and alternative methods.

The Methods Update Rules section contains every regulatory action that has changed 40 CFR Part 136.  The other sections are redundant to the Methods Update Rules and discuss rules that are specific to contaminant types.

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Methods Update Rules

The EPA regularly updates the list of approved methods and parameters to reflect advances in technology, regulatory needs, refine quality assurance and quality control requirements, and provide entities more choices of approved compliance monitoring methods.  The 23 Method Update Rules (including routine rules) have been promulgated since 40 CFR Part 136 came into existence in October of 1973.

Sequential History of Clean Water Act Method-Related Rulemakings, Including Method Update Rules (MURs), and Introducing a MUR Numbering System
MUR # Date Promulgated/FRN Brief Description
MUR 22 To be proposed in 2024 Intends to contain new Methods 1633 for PFAS compounds, 1621 for adsorbable organic fluorine, and 1628 for polychlorinated biphenyl congeners. Will add methods from voluntary consensus standard bodies (VCSB) for PFAS, peracetic acid, and hydrogen peroxide, assuming the VCSB provide adequate validation data. Other new methods, method withdrawals, and holding time changes are also considered.
rMUR 2 April 16, 2024, 89 FR 27288 Included several EPA methods, over 50 VCSB methods, and two alternate test procedures (ATPs) for dioxins and furans.
rMUR 1 May 19, 2021, 86 FR 27226 Included an EPA method, over 100 VCSB and USGS methods, and three ATPs. This was the first rule that the EPA labeled as a Routine Methods Update Rule or rMUR. 
MUR 21 August 28, 2017, 82 FR 40836 Updated Methods 624, 625, and 608 for volatiles, semivolatiles, and pesticides/PCBs to 624.1, 625.1, and 608.3, revised the method detection limit procedure, approved other VCSB method updates and revisions and six ATPs.
MUR 20 May 18, 2012, 77 FR 29758 Added Method 1664, Revision B for Oil and Grease, allowed collision cell for inductively couple plasma methods for metals, added methods to Table IG for pesticide active ingredients, added Methods 1622 and 1623 for Cryptosporidium to Table IH, and other method updates and revisions including eight ATPs. The rule also clarified the procedures at Parts 136.4 and 136.5 for obtaining approval of ATPs, revised Part 136.6 to provide additional examples of allowed and prohibited method modifications, thereby reducing the need for an ATP application for modifications that do not change the underlying chemistry or determinative technique in a method, and added Part 136.7 that specifies the “essential” quality control elements needed for Clean Water Act compliance monitoring.
MUR 19 March 26, 2007, 72 FR 14220 Revised Table 1A for biological pollutants in wastewater and sewage sludge, and created Table IH for biological pollutants in ambient waters. Included a cross reference between 40 CFR Part 136 and 503.
MUR 18 March 12, 2007, 72 FR 11200 Added Methods 200.2 and 200.8 Rev 5.4, and other metals methods from the EPA and VCSB, and various other methods, including three ATPs. It was also the rule that explicitly allowed capillary columns to be used in the older GC methods (e.g., 601-613, 624, 625, and 1624B).
NA September 19, 2003, 68 FR 54934 Correction notice to the MUR below, not a method update rule.
MUR 17 July 21, 2003, 68 FR 43272 Approved test methods for E. coli, enterococci, Cryptosporidium, and Giardia for ambient freshwater quality monitoring and for enterococci for ambient and marine water quality monitoring including methods using most probable number and membrane filtration techniques. These included Methods 1600 for enterococci, 1622 and 1623 for Cryptosporidium, and 1623 for Giardia as well as VCSB methods and methods reviewed as ATPs.
MUR 16 November 19, 2002, 67 FR 69952 Second promulgation of Whole Effluent Toxicity (WET) Test Methods that ratified approval of ten WET methods that were subjected to an extensive multi-laboratory validation study as part of a settlement agreement designed to resolve litigation over the October 16, 1995 rulemaking that originally approved WET test methods. This rule withdrew approval for the Holmesimysis costata acute test and the Champia parvula reproduction test.
MUR 15 October 29, 2002, 67 FR 65876 Added Method 1631E for Trace Level Mercury
MUR 14 December 30, 1999, 64 FR 73414 Added Method 1677 for Available Cyanide
MUR 13 June 8, 1999, 64 FR 30417 Added Method 1631B for Trace Level Mercury
MUR 12 May 14, 1999, 64 FR 26315 Added Method 1664B for Oil and Grease
MUR 11 September 15, 1997, 62 FR 48394 Added Method 1613B for Dioxins and Furans
MUR 10 October 16, 1995, 60 FR 53529 The first promulgation of WET methods covering acute and chronic toxicity of effluents to freshwater and marine organisms. The rule approved freshwater acute toxicity methods involving Daphnia, Ceriodaphnia, Fathead Minnow, Rainbow, Trout, Brook Trout, and Bannerfish Shiner, and the estuarine or marine acute toxicity methods involving Mysid, Sheepshead Minnow, and Menidia species. It also approved freshwater chronic toxicity methods for Fathead Minnow, Ceriodaphnia, and Selenastrum, and the estuarine or marine acute toxicity methods involving Sheepshead minnow, Menidia beryllina, Mysidopsis bahia, Arbacia punctulata, and Champia parvula.
MUR 9 August 28, 1995, 60 FR 44670 Added three more Total Kjeldahl Nitrogen methods.
MUR 8 April 4, 1995, 60 FR 17160 Technical corrections to the EPA, USGS, SM, ASTM, and AOAC methods in various tables.
MUR 7 January 31, 1994, 59 FR 4503 Updated various Standard Methods and ASTM Methods, and revised Table II for holding times, preservatives, and containers.
MUR 6 August 15, 1990, 55 FR 33434 Added ICP, GFAA, and Flame AA metals methods and the associated validation study results.
MUR 5 June 15, 1990, 55 FR 24532 Added additional direct current plasma methods for metals.
MUR 4 September 3, 1987, 52 FR 33542 Added direct current plasma methods for 23 metals.
MUR 3 October 4, 1985, 50 FR 40703 Titled “Test Methods for Nonconventional Pesticide Pollutants,” this rule promulgated various 600-series methods for pesticides under 40 CFR Part 455.47, Subpart D. Those methods eventually became part of the later tables at Part 136.
MUR 2 October 26, 1984, 50 FR 690 Added most of the 600-series methods and many other EPA methods from 1979. This rule introduced many of the method tables that currently exist in 40 CFR Part 136.3, along with the original MDL procedure.
MUR 1 December 1, 1976, 41 FR 52780 Labeled “Amendments,” this rule added parameters and methods that were deemed nearly identical to already approved methods.
Original methods October 16, 1973, 38 FR 28758 The original list of approved methods for NPDES permits titled “Guidelines Establishing Test Procedures for Analysis of pollutants,” a title that was used for many subsequent MURs.

Oil and Grease Methods

Method 1664A

Method 1664B

Alternative Method: ASTM D7575

Final Decision on use of ASTM Method D7575 for measurement of oil and grease
  • Federal Register Notice (March 6, 2013)
  • Support Documents
    • Limited-Use ATP Application
    • Limited-Use ATP Method Documentation Form
    • Performance Comparison Form - Clean Matrix
    • Performance Comparison Form - Effluent Matrix
    • Oil and Grease ATP Comparison Worksheet
    • Fact Sheet
    • Guidance for Limited-Use ATP Applications for D7575

Cyanide Methods

Mercury Methods

Dioxins and Furans

  • Final Rule (September 15, 1997)
    Approval of Method 1613B

Chromium (VI)

Clean Water Act Analytical Methods

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Last updated on August 26, 2024