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Description: <div><div><b>Description: </b>National Measured Dissolved Calcium Data derived from data stored in the U.S. EPA Water Quality Portal.</div><div><b>Data Date Range:</b> 01/2000 – 12/2023</div><div><b>Acquisition Date:</b> 1/25/2024</div><div><b>Query Links:</b> <a href="https://www.waterqualitydata.us/#sampleMedia=Water&amp;characteristicName=Calcium&amp;startDateLo=01-01-2000&amp;startDateHi=12-31-2023&amp;mimeType=csv&amp;dataProfile=narrowResult&amp;providers=NWIS&amp;providers=STEWARDS&amp;providers=STORET" target="_blank">https://www.waterqualitydata.us/#sampleMedia=Water&amp;characteristicName=Calcium&amp;startDateLo=01-01-2000&amp;startDateHi=12-31-2023&amp;mimeType=csv&amp;dataProfile=narrowResult&amp;providers=NWIS&amp;providers=STEWARDS&amp;providers=STORET</a></div><div><b>Min. Value:</b> -214.934</div><div><b>Max. Value:</b> 23000000</div><div><b>Units in Original/Source Dataset:</b> &lt;Null&gt;, %, % recovery, count, lb/day, mg/g, mg/kg, mg/l, mg/L, mg/l CaCO3, mg/l CaCO3**, mg/m2, MPN, ppb, ppm, ueq/L, ug/g, ug/kg, ug/L, ug/l, umol/L</div></div><div><br /></div><div><div><b>Background</b></div><div>Dissolved calcium in freshwater can have both positive and negative effects on aquatic life and other uses of water. Some natural and anthropogenic sources of calcium ions are weathering of rocks and minerals, particularly limestone and sandstone, which releases calcium ions into the water. Anthropogenic activities that increase calcium in streams include agricultural runoff, dissolution of mine waste, demineralization of concrete, wastewater discharge, and industrial processes. Dissolved calcium can somewhat reduce metal toxicity (e.g., <a href="https://www.epa.gov/wqs-tech/copper-biotic-ligand-model" target="_blank">EPA 2024a</a>), but excess levels can also be associated with ionic stress for aquatic life (<a href="https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=233809" target="_blank">EPA 2011</a>).  It can lead to scaling and deposits in water infrastructure, affecting water supply systems (<a href="https://www.epa.gov/sites/default/files/2018-10/documents/quality-criteria-water-1976.pdf" target="_blank">EPA 1976</a>; USEPA 2024b). </div><div><br /></div><div>Dissolved calcium ion concentration is in freshwater is typically measured by atomic absorption spectroscopy (EPA 6010D, (USEPA 2014) or inductively-coupled plasma atomic emission spectroscopy (ICP-AES) (EPA 200.7(USEPA 1994). Therefore, data reliability depends upon analytical quality and then data transcription into the water quality exchange. </div><div><br /></div><div><b>Dataset</b></div><div>This dataset focuses primarily on samples reported as dissolved calcium cations.  Unit conversions were normalized to mg/l as listed in Table 1. </div><div><br /></div><div>This dataset is a collection surface water disolved calcium samples collected across the United States from 2000-2023 from the Water Quality Portal (WQP), which integrates publicly available water quality data from the USGS National Water Information System (NWIS) and the EPA Water Quality Exchange (WQX) Data Warehouse. These water quality data records are provided by many federal, state, and tribal organizations and other partners. Because these data are from secondary sources, the U.S. EPA cannot ensure that the information is accurate, current, or complete. Therefore, users should verify the data from the original sources before drawing site specific conclusions.</div></div><div><br /></div><div><div><b>Quality Assurance/Quality Control (QA/QC) and identified issues</b></div><div>An automated Quality Assurance/Quality Control (QA/QC) protocol was developed using a mix of Python and R-scripts to remove or identify potentially erroneous values (outliers) appearing in the WQP data. The quality of the WQP measured data was evaluated as follows.  </div></div><div><div><ul><li>Generally – do not delete data. Add a screening/flagging column to keep track of decision-making to remove records/observations.</li><li>Review the geographic/temporal scope and data types of the acquired data to the project objectives—it might not be necessary to process all data from a given data set. Map stations in a GIS to further refine and select data based on analysis selection criteria: geographic area, watersheds, bounding box, waterbody type, etc. This also provides the opportunity to conduct quality assurance checks based on spatial location (e.g., are the “estuarine” sites located near the coast).</li><li>Flag values reported with units of measurements different than mg/L.</li><li>Review and flag samples identified in the WQP with sample processing issues (e.g., suspected contamination, exceeding sampling hold time, no reported value, below reporting value). Many of the samples that met these criteria were already found and identified by WQP QA/QC data process.</li><li>Convert all relevant calcium values to mg/L or flag values where there is no direct path for unit conversion Table 1.</li><li>Flag values outside of the known maximum and minimum (0.05 – 500) ranges of dissolved calcium in freshwater systems. This range falls within the range of dissolved calcium values observed in freshwater systems. This dataset contains well samples along with stream collected samples and map range values were widened to include those locations (USEPA, 2022).</li><li>Review and flag samples identified in the WQP with sample processing issues so that value is not used in summarization calculation (e.g., suspected contamination, exceeding sampling hold time, no reported value, below reporting value).  </li><li>Parse/filter out various measurement compositions (Total vs Dissolved) for summarization to use only data denoted as Dissolved.</li><li>Summary statistics – Calculate basic statistics (mean, median, standard deviation, range, last measurement, maximum, minimum).</li></ul></div></div><div><br /></div><div style="text-align:center;"><img alt="Unit conversion to mg/L for measured dissolved calcium samples." src="https://lh3.googleusercontent.com/pw/AP1GczPCzbmWZpeDgIjetwFTogMDQYvYPPQdRzst8nkcblCi-Ovq4YT2cyZPPuqCZabcnhmVDtVwLS0czeFsmhKbtxKqLNbsnWRYLpI3oM6QQIWKhLxUlkbWy_5C3X4w_0J8lmt811M1EsCPHkrn9nsD_61Mig=w676-h700-s-no-gm?authuser=0" /><br /></div><div style="text-align:center;"><i>Table 1. Unit conversion to mg/L for measured dissolved calcium samples.</i></div><div style="text-align:center;"><i><br /></i></div><div style="text-align:left;"><div style>Examples of errors found include negative calcium values, units of measurements not consistent with calcium measurements (e.g., &lt;Null&gt;, %, % recovery, count, lb/day, mg/m2, MPN,), and values well above known dissolved calcium ranges in freshwater systems. Users should verify the data from the original sources before drawing site specific conclusions. Individual contributing organizations can still be found in the final and original datasets if the end user would like to filter for only specific sampling partners.</div><div style><br /></div><div style>The resulting dataset is presented as a summarized collection information for each unique sampling location and the original data flagging process helps to exclude unreliable and errant values from the final statistics. The R code developed to perform the QA/QC steps are available from <a href="mailto:cormier.susan@epa.gov" target="_blank">cormier.susan@epa.gov</a>.</div><div style="font-style:italic;"><br /></div><div style><div style><b>Terms of Use</b></div><div style><b><br /></b></div><div style><b>Freshwater Explorer Data Disclaimer</b></div><div style><br /></div><div style>This data is intended for exploratory and discussion purposes. Although statutory provisions and U.S. Environmental Protection Agency (EPA) regulations contain legally binding requirements, these data and related information are not regulatory, nor do they change or substitute for any provisions or regulations. The information does not substitute for the Clean Water Act, a National Pollutant Discharge Elimination System permit, or EPA or state regulations applicable to permits; nor is this material a permit or regulation itself. Thus, it does not impose legally binding requirements on EPA, states, tribes, or the regulatory community. This information does not confer legal rights or impose legal obligations on any member of the public. Mention of any trade names, products, or services is not and should not be interpreted as conveying official EPA approval, endorsement, or recommendation.</div><div style><br /></div><div style>While EPA has used its best efforts to include complete and accurate information in this system, EPA cannot be held responsible for errors or omissions and is not liable for any direct, indirect, or consequential damages resulting from using this secondary information. Some potential sources of error have been assessed by the U.S. EPA resulting in the removal of some samples from the original data sets. However, all sources of potential error cannot be eliminated from the measured data reported in the Freshwater Explorer or the data used to develop predictive models. Therefore, the U.S. EPA cannot fully ensure either the original data or the values calculated from them. Conclusions and assessments drawn from the use of the Freshwater Explorer are the responsibility of the user.</div><div style><br /></div><div style>Please check sources, scale, accuracy, dates, and other available information. Please confirm that you are using the most recent copy of both data and metadata. Reliance on the information contained in this system by any party cannot be used as a defense in any administrative or judicial proceeding.</div><div style><br /></div><div style>This dataset may be revised periodically. EPA can revise this dataset without public notice to reflect changes in EPA policy, guidance, and advancements in the field of biological assessments. EPA welcomes public input on this document at any time. Send comments to FreshwaterExplorer@epa.gov, National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr, Cincinnati, OH 45268.</div><div style><br /></div><div style><b>Preferred citation:</b> Leppo, E., Wharton, C., and Cormier. S. 2024. U.S. EPA Freshwater Explorer v2 national measured dissolved calcium metadata and dataset. USEPA. https://arcg.is/0OuDn80</div><div style><br /></div><div style><b>Original data sources:</b> https://www.waterqualitydata.us/#sampleMedia=Water&amp;characteristicName=Calcium&amp;startDateLo=01-01-2000&amp;startDateHi=12-31-2023&amp;mimeType=csv&amp;dataProfile=narrowResult&amp;providers=NWIS&amp;providers=STEWARDS&amp;providers=STORET</div><div style><br /></div><div style><b>References</b></div><div style>USEPA. 1976. Quality Criteria for Water. EPA 440-9-76-023. <a href="https://www.epa.gov/sites/default/files/2018-10/documents/quality-criteria-water-1976.pdf" target="_blank">https://www.epa.gov/sites/default/files/2018-10/documents/quality-criteria-water-1976.pdf</a>.</div><div style><br /></div><div style>U.S. EPA. 1994. “Method 200.7: Determination of Metals and Trace Elements in Water and Wastes by Inductively Coupled Plasma-Atomic Emission Spectrometry,” Revision 4.4. Cincinnati, OH. </div><div style><br /></div><div style>USEPA. 2011A Field-Based Aquatic Life Benchmark for Conductivity In Central Appalachian Streams (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-10/023F. <a href="https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=233809" target="_blank">https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=233809</a>.</div><div style><br /></div><div style>USEPA. 2014. &quot;Method 6010D (SW-846): Inductively Coupled Plasma-Atomic Emission Spectrometry,&quot; Revision 4. Washington, DC. <a href="https://www.epa.gov/esam/epa-method-6010d-sw-846-inductively-coupled-plasma-atomic-emission-spectrometry" target="_blank">https://www.epa.gov/esam/epa-method-6010d-sw-846-inductively-coupled-plasma-atomic-emission-spectrometry</a>.</div><div style><br /></div><div style>USEPA. 2022. National Rivers and Streams Assessment 2023 - 2024: Laboratory Operations Manual. EPA841-B-22-008. U.S. Environmental Protection Agency, Office of Water, Washington, DC. <a href="https://www.epa.gov/system/files/documents/2023-06/NRSA2324_LOM_v1.0.pdf" target="_blank">https://www.epa.gov/system/files/documents/2023-06/NRSA2324_LOM_v1.0.pdf</a></div><div style><br /></div><div style>USEPA. 2024a. Copper Biotic Ligand Model. Water Quality Standards: Regulations and Resources. <a href="https://www.epa.gov/wqs-tech/copper-biotic-ligand-model" target="_blank">https://www.epa.gov/wqs-tech/copper-biotic-ligand-model</a></div><div style><br /></div><div style>USEPA. 2024b. Secondary Drinking Water Standards: Guidance for Nuisance Chemicals. <a href="https://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals" target="_blank">https://www.epa.gov/sdwa/secondary-drinking-water-standards-guidance-nuisance-chemicals</a>.</div><div style="font-style:italic;"><br /></div></div></div>

Copyright Text: Water Quality Portal. Washington (DC): National Water Quality Monitoring Council, United States Geological Survey (USGS), Environmental Protection Agency (EPA); 2021. https://doi.org/10.5066/P9QRKUVJ.

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Last Edit Date: 10/9/2024 3:30:22 PM

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