U.S. ENVIRONMENTAL PROTECTION AGENCY
Best Practices for Submitting Metals Data to the
Water Quality exchange (WQX)
Created in collaboration with the U.S. Environmental Protection
Agency, the U.S. Geological Survey and Water Quality exchange
state partners

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Data submitted via WQX is published through the Water Quality Portal and made available with USGS, USDA and other
state, tribal, territory, academic, and volunteer partners. The goal of the WQX Metals Best Practices Guide is to increase
the quality of metals data records in WQX by making it easier for data providers to capture metadata elements,
increasing consistency of metadata elements utilized, and removing confusion and ambiguity for secondary data users.
This guide outlines how WQX data submitters can capture a complete metals record which includes: a metals
characteristic, sample fraction, and analytical method. It is preferential for organizations to publish their data using a
national analytical method to enhance data reuse and comparability with other datasets available through the Water
Quality Portal. This document is a direct product of the WQX Metals Quality Assurance Workgroup, comprised of
representatives from EPA, USGS, external stakeholders, and several states. The Metals Quality Assurance team has
included details regarding metadata element capture decision points, how to propose new metals characteristics for use
in WQX, and commonly reported metal records combinations. This guidance does not require any new metadata to be
submitted to WQX but does advise data submitters to make adjustments to characteristic names and new characteristic
name proposals.
To learn about best practices for capturing Nutrient data and metadata elements see the WQX Nutrient Best Practices
Guide at https://www.epa.gov/waterdata/wqx-nutrients-best-practices-guide
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Metals data are collected, analyzed, and then published to WQX by hundreds of organizations throughout the country.
Each of those organizations have unique projects and purposes for which they are collecting valuable and high-quality
data. It is natural that each of those organizations store metals data with varying metadata elements and define
metadata terms for their own analysis purposes. Likewise, data collected by the organization may have metadata
qualities that can be assumed and thus not captured in the dataset. However, once the data is reported nationally, those
metadata nuances that can be assumed at an organizational level, can no longer be assumed at the national level. By
clarifying ambiguous terms, providing user guidance, and improving WQX submission requirements, the WQX metals
data can be captured at such detail to facilitate secondary data usage.
The Water Quality exchange (WQX) Metals Best Practices Guide was created to assist organizations in submitting metals
data to WQX, by promoting consistency when capturing metadata and removing confusion and ambiguity for secondary
data users. This document is a direct product of the WQX Metals Quality Assurance Workgroup, comprised of
representatives from EPA, USGS, external stakeholders, and several states. The QA Workgroup addressed three areas of
concern for metal characteristics: (1) Method Speciation, Ions and Sample Fraction, (2) National Analytical Methods, and
(3) Metal Results. This Guide is designed to be used with WQX version 2.0, although some of these practices address
elements that may become required in WQX 3.0 (scheduled for release in 2018-2019). It is recommended to adopt them
now in anticipation of their inclusion in 3.0.
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Speciation
Metals are only ever reported as a single speciation, thus the workgroup determined that method speciation is a
nonessential metadata element and should not be a required data element. For example: Aluminum is always reported

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"as Al", thus there is no need to require data submitters to report metadata that can be reasonably assumed. Ionic
forms, which are sometimes referred to as the speciation of a metal, are identified as the ionic form in the characteristic
name, such as Arsenic(lll) or Chromium(VI), as described below.
Ions
Metals are found in multiple ionic forms in nature, which becomes important when assessing bioavailability of the
metal. WQX needs to allow for the reporting of these ionic variants, such as Chromium(VI) and Chromium(lll). After
review of the current WQX metals characteristic list and the EPA Substance Registry System (SRS), the team determined
the format for establishing new metal ion characteristics will be the metal name followed by the ion numeric value
shown in the Chromium example above. When requesting ionic forms of metals to be added to the WQX characteristics
allowable value list, please do so using the preferred format.
Sample Fraction
The sample fractions of "Total" and "Dissolved" when used with metals indicate an unfiltered and filtered sample,
respectively. The workgroup found that the use of "Total" and "Dissolved" for metals is not ambiguous because only one
speciation can be reported for each characteristic, eliminating the possibility that "Total" could indicate the sum of all
forms. Total recoverable on the other hand, are the metals solubilized by digestion with strong solutions of mineral acids
and is sometimes incorrectly used synonymously with Total metals. Please check with your lab to ensure you are
recording the correct sample fraction.
NOTE: To capture filter pore size in a data submission, please capture the information in the Result Comment metadata
element.
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The table below was created by the QA Workgroup to show common combinations of the WQX metadata elements,
characteristic, sample fraction, and national methods, needed for a complete metals result.
Referencing a national method under the laboratory analysis method metadata element improves data consistency. And
although WQX does allow organizations to create unique Method IDs, this option is primarily for cases when the method
has not yet been captured in the domain value list. Organizations should map their lab analytical methods to an existing
WQX lab analytical method if at all possible. Optimally, the laboratory analyzes and reports data using a recognized
national method such as APHA or USEPA (captured in the WQX metadata element "method context").
If the lab is using a method or SOP equivalent to a recognized national method such as USEPA, APHA Standard Methods,
ASTM, etc., report the recognized national method. If you cannot map your analytical method to a national method, and
must create a custom method, it is not recommended to use words like "QAPP" or "UNKNOWN" in the method ID.
These types of method IDs require a secondary data user to find documents that are not readily available, and may
result in the data not being used because the methods are inaccessible.. Analyzing and reporting data with national
methods increases the archival and reuse value of the data because it can be more readily combined with data from
other organizations.
The Analytical Methods listed in table 1 are the most commonly reported methods for each given metal characteristic.
The methods are not directly applicable to each possible metal result combination with sample fraction. There exist less

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frequently used methods included on the WQX allowable values list that are not listed in the table below. To look up
these additional method IDs, go to https://www.epa.gov/waterdata/storage-and-retrieval-and-water-qualitv-exchange-
domain-services-and-downloads#domain. The National Environmental Methods Index is another reference for analytical
methods https://www.nemi.gov/home/. If the method used is a nationally recognized method or you are a node
submitter, please email the STORET helpdesk (storet@epa.gov ) with the NEMI information and your ID request. If the
method is not in the table below, the domain value lists, or NEMI, then you should add a new analytical method by
logging into WQX web. To add an analytical method in WQX Web, select "Domain Values" > "Edit Analytical Methods" >
Identify the Org ID as the context > input the analytical method > Save.
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A complete metal result contains a characteristic name, a result (or result detection condition) value and unit, a sample
fraction, and analytical method. If reported as above or below a quantitation limit by the laboratory, the complete
record will need to contain a detection limit type, value, and unit instead of a result value and unit.
Table 1: Metals Result Guidance at a Glance
Table 1: The table below shows each of the recommended characteristics to be reported to WQX, any previous WQX allowable values that are
synonyms of the recommended characteristic, sample fractions which can be reported for those characteristics, and the most commonly reported
national methods for those characteristics.
Preferred WQX
Characteristic
Name
Result Sample Fraction
Acid Soluble Recoverable
Bed Sediment Total
Dissolved Total Recoverable
Commonly-Reported Analytical Methods for Characteristic
Aluminum
USEPA: 200.8, 200.7, 6010C, 1638, 6010B, 6010A, 6020A
APHA: 3120
HACH: 10215
Antimony
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 6020, 1638, 6020A, 6010C, 6010B, 6020,1620A, 6020B, 200.7
Arsenic (V)
Former Synonyms -
Arsenic ion (5+) &
Arsenate
Total
Dissolved
USEPA: 200.8, 6010C, 6020,1638, 200.7, 6020A, 200.9, 6010B, 1632
APHA: 3114-B, 3113-B
Arsenic
Bed Sediment Recoverable
Dissolved Total
Fixed Total Recoverable
Inorganic
USEPA: 200.8, 6010C, 1638, 200.7, 6020A, 200.9, 6010B, 1632
APHA: 3114-B, 3113-B
Arsenic (III)
Former Synonyms -
Arsenic ion (3+) &
Arsenite
Total
Dissolved
USEPA: 1632
APHA: 3114-B
Barium
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 200.7, 6010C, 1638, 6010B, 6020A, 6020, 6010C, 1620A,
Beryllium
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 200.7,1638, 6020, 6010B, 6020A, 1620A, 6020B

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Preferred WQX
Characteristic
Name
Result Sample Fraction
Commonly-Reported Methods for Characteristic
Boron
Bed Sediment Recoverable
Dissolved Total
Dissolved Total
Fixed Total Recoverable
Inorganic
USEPA: 200.7, 200.8, 6020, 6010C, 6010B,
APHA: 2130
Cadmium
Bed Sediment Recoverable
Dissolved Total
Pot. Dissolved Total Recoverable
USEPA: 200.8, 200.7, 6010C, 6020, 1638, 6020A, 6010B, 200.12, 200.9
HACH: 10217
Calcium
Total
Dissolved
USEPA: 200.7, 6010C
Chromium
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 200.7, 6010C, 1638, 6020, 6020A, 200.12, 6010B, 1620(A)
APHA: 3113-B
HACH: 10218
Chromium(lll)
Total
Dissolved
USEPA: 6010C, 7199
APHA: 3500-CR(D)
Chromium(VI)
Dissolved Total
Recoverable Total Recoverable
USEPA: 218.6, 7199, 7196A, 200.8
APHA: 3500-CR(D), 3500-CR(B), 3500-CR(D)
Cobalt
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 200.7, 6020, 6020A, 6010C, 6010B
Copper
Bed Sediment Recoverable
Dissolved Total
Pot. Dissolved Total Recoverable
USEPA: 200.8, 200.7, 6010C, 1638, 6020, 6010B, 200.9
APHA: 3120, 3500-CU(B)
HACH: 10215
Ferrous ion
Total
Dissolved
HACH: 8146
Gadolinium
Total
Dissolved
USEPA: 200.8
Gold
Total
Dissolved
USEPA: 200.7, 200.8
Iron
Bed Sediment
Dissolved
Recoverable
Total
Total Recoverable
Lead
Bed Sediment Suspended
Dissolved Total
Pot. Dissolved Total Recoverable
Recoverable
USEPA: 200.7, 200.8,1638, 6010B, 6010C, 6020A, 6010A
APHA: 3111-B, 3120
HACH: 10215
Lithium
Bed Sediment Recoverable
Dissolved Total
USEPA: 200.8, 200.7, 6010C, 6020, 1638, 6010B, 6020A, 200.9, 200.12
HACH: 10216
Magnesium
Total
Dissolved
USEPA: 200.7, 6010C
Manganese
Bed Sediment Suspended
Dissolved Total
Recoverable Total Recoverable
USEPA: 200.8, 200.7, 6010B
Mercury
Bed Sediment Suspended
Dissolved Total
Recoverable Total Recoverable
USEPA: 200.7, 200.8,1638, 6010C, 6010B, 6020A, 1620(A), 6020
APHA: 3120, 3111-B
Molybdenum
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 245.1, 245.7,1631, 1631E, 7471B, 7471A, 200.8, 7470A, 7473
APHA: 3112-B

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Preferred WQX
Characteristic
Name
Result Sample Fraction
Commonly-Reported Methods for Characteristic
Nickel
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.7, 200.8, 6020, 6020A, 6010C, 6010B
Potassium
Bed Sediment Total
Dissolved Total Recoverable
Free Available
USEPA: 200.7, 200.8, 6010B, 1638, 300.1
APHA: 3120, 3111-B
Selenium
Bed Sediment Suspended
Dissolved Total
Dissolved Total
Pot. Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 200.7, 6010C, 1638, 6020, 6020B, 6020A, 6010B, 200.9
HACH: 10220
Silver
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 6010C, 6020, 1638, 200.7, 6020A, 200.9, 6010B
APHA: 3114-C, 3114-B, 3113-B
Sodium
Bed Sediment Total
Dissolved Total Recoverable
Fixed Recoverable
Free Available
USEPA: 200.7, 200.8, 6010B, 6020A, 273.1,
APHA: 3120B, 3111-B
Strontium
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 200.7, 6020, 6010C, 1638, 6020A, 6010B, 200.9, 6020B
Thallium
Bed Sediment Total
Dissolved Total Recoverable
USEPA: 200.7, 200.8,1638, 6010B, 6020,
Tin
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 1638, 6020, 6020A, 6010C, 200.7, 6010B, 6020B, 300.0
Titanium
Bed Sediment Total
Dissolved Total Recoverable
USEPA: 200.7, 200.8
Vanadium
Bed Sediment Total
Dissolved Total Recoverable
Recoverable
USEPA: 200.8, 200.7
Zinc
Bed Sediment Recoverable
Dissolved Total
Pot. Dissolved Total Recoverable
USEPA: 200.8, 200.7, 6010C, 6020. 6020A, 6010B, 6010C, 1620(A), 1638

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