Data sources used for EPA's Decision to Partially Disapprove and Identify 40 Waters for
Inclusion on Missouri's 2020 303(d) List

EPA followed MDNR's Listing methodology and the lake numeric nutrient criteria. The
methodology may be found here: https://dnr.mo.gov/env/wpp/waterqualitv/303d/docs/2020-lmd-
cwc-apprvd-7-22-2019. pdf.

Section 303(d) of the Clean Water Act and EPA regulations. 40 C.F.R. section 130.7(b) provides
that each state shall assemble and evaluate "all existing and readily available water quality-
related data and information." Specifically, the state's submission did not demonstrate that it
satisfied the obligation to assemble and evaluate all existing and readily available water quality-
related data and information. Per MDNR's listing methodology, only the three most recent years
of data were used for purposes of assessing impairment for those lakes not found in Table N.
Additionally, per 40 C.F.R. section 130.7(b), EPA must consider "all existing and readily
available water quality-related data and information," therefore, EPA used data from slightly
outside Missouri's assessment protocol, as described in our decision document available here:
https://www.epa.gov/sites/production/files/2020-12/documents/mo2020303dpartialapproval.pdf.
The Data Supporting Listing column in Appendix C provides an indication of what data caused
impairment.

Missouri Lakes and Reservoirs Long-Term Limnological Dataset ver 1

Data reviewed by EPA was comprised of data collected by the University of Missouri
Limnology lab through grants from MDNR. While nearly all of MDNR's lake data may be
accessed via MDNR's website, a more accessible and more complete dataset is publicly
accessible and found here: https://doi.org/10.6073/pasta/86d8dl76e91410566b4de51df44c2624

Missouri Department of Conservation - Missouri Pollution and Fish Kill Investigations

To assess if eutrophication factor A) occurrence of eutrophication-related mortality or morbidity
events for fish and other aquatic organisms (i.e., fish kills) occurred at a lake, EPA reviewed fish
kill reports/data from MDC from 1995 to 2018. MDNR provided a summary spreadsheet
developed by MDC that had additional details not provided in the yearly reports. For the 40 lakes
in Appendix C, data from the years 2014, 2015, 2017, and 2018 are referenced. These Fish Kill
Reports may be accessed here: https://www.epa.gov/mo/epas-action-add-waters-missouris-2020-
list-impaired-waters.

Additional Data for EPA's review

EPA will consider any comments submitted during the public comment period described in the
Public Notice. EPA would appreciate any additional data that the public or agencies might have
that were not included in the above sources. The type of data that would be most helpful would
be:

•	Samples were collected and analyzed under a Quality Assurance/Quality Control
(QA/QC) protocol;

•	Samples were analyzed consistent with Standard Method procedures;

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A copy of the organization's QA/QC protocol and standard operating procedures is
provided;

Data is reported in standard units as recommended in the relevant approved methods;
Data is accompanied by precise sample location(s), preferably in decimal degrees or
Universal Transverse Mercator (UTM);

Data is in a Microsoft Excel or compatible format.

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