ArcGIS REST Services Directory
JSON

Layer: Chlorophyll A (ID:4)

View In:   Map Viewer

Name: Chlorophyll A

Display Field: OrganizationFormalName

Type: Feature Layer

Geometry Type: esriGeometryPoint

Description: <div><b>Description:</b> National Measured Chlorophyll a 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=Chlorophyll%20a&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=Chlorophyll%20a&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> -200</div><div><b>Max. Value:</b> 999.999</div><div><b>Units in Source/Original Dataset:</b> &lt;Null&gt;, #/L, g/m2, IVFU, m, mg, mg/cm2, mg/cm3, None, mg/l, mg/L, mg/m2, mg/m3, ppb, ppm, ug/L, ug/l, ug/net, RFU, ug, ug/cm2</div><div><br /></div><div><div><b>Background</b></div><div>Chlorophyll a is a specific form of chlorophyll used in oxygenic photosynthesis. It absorbs most energy from wavelengths of violet-blue and orange-red light. It is a critical pigment found in all photosynthetic organisms, including algae and cyanobacteria, and it is often used as an indicator of the amount of algae (or phytoplankton) in freshwater systems. High levels of chlorophyll a can indicate eutrophic conditions, where nutrient enrichment (often from agricultural runoff or sewage discharge) leads to excessive algal growth. Measuring chlorophyll a concentrations helps assess the trophic state of the waterbody (USEPA 2022, USEPA 2024).  Rates of increase can be used to predict fish die offs from hypoxia (low oxygen levels) as plant material decays and the probability of cyanobacterial blooms that are toxic to wildlife and people.</div><div><br /></div><div>Chlorophyll a is typically measured by extraction in 90% acetone and analyzed by fluorometry (<a href="https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NERL&amp;dirEntryId=309417" target="_blank">EPA 445.0</a>, <a href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=309415&amp;Lab=NERL" target="_blank">EPA 446.0</a>)</div></div><div><br /></div><div><div><b>Dataset</b></div><div>This dataset is a collection chlorophyll a samples, collected and summarized 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. As such, 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) in WQP. 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 µg/L and that have no conversion factor. </li><li>Convert all relevant chlorophyll a values to mg/L and flag values where there is no direct path for unit conversion Table 1.</li><li>Flag values outside of the range of values that have been observed in surface water samples across the continental United States (0– 11,000 µg/L)(USEPA, 2022).</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).</li></ul><div style="text-align:center;"><img alt="Unit conversion to mg/L for measured chlorophyll A." src="https://lh3.googleusercontent.com/pw/AP1GczMOwz4jqBUkDURom7xq07znu-lYzJlVqY92frLSaDzTmHEesjVnhyIhIwocflWM1Oc4Y4oOGSpn4tqxMNzQSDT2g-LPnXcslvOpU3NUpBaE-WOpCZzgznfhsJs5S1zeBJ8CRnF3G6gpo_t5ZseWQ-lfEQ=w884-h348-s-no-gm?authuser=0" /></div></div></div><div style="text-align:center;">Table 1. Unit conversion to mg/L for measured chlorophyll a samples.</div><div style="text-align:center;"><br /></div><div style="text-align:left;"><div>Examples of errors found include negative chlorophyll a values, units of measurements not consistent with chlorophyll a measurements (Table 1), and values well above known chlorophyll a 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><br /></div><div>The resulting dataset is presented as 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 data set is set to be updated on an annual basis to account for sample additions and updates continually being added to the WQP. 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><br /></div><div><br /></div></div><div><div><b>Terms of Use</b></div><div><b><br /></b></div><div><b>Freshwater Explorer Data Disclaimer</b></div><div><br /></div><div>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><br /></div><div>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><br /></div><div>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><br /></div><div>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, Center for Environmental Measurement and Modeling, Office of Research and Development, U.S. Environmental Protection Agency, 26 W. Martin Luther King Dr, Cincinnati, OH 45268.</div></div><div><br /></div><div><div><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. <a href="https://arcg.is/0OuDn80" target="_blank">https://arcg.is/0OuDn80</a></div><div><br /></div><div><b>References</b></div><div>Arar, E. J. Method 446.0: In Vitro Determination of Chlorophylls a, b, c + c and Pheopigments in 1 2Marine And Freshwater Algae by Visible Spectrophotometry. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/005, 1997. <a href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=309415&amp;Lab=NERL" target="_blank">https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=309415&amp;Lab=NERL</a></div><div><br /></div><div>Arar, E. J. and G. B. COLLINS. Method 445.0 In Vitro Determination of Chlorophyll a and Pheophytin a in Marine and Freshwater Algae by Fluorescence. U.S. Environmental Protection Agency, Washington, DC, 1997. <a href="https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NERL&amp;dirEntryId=309417" target="_blank">https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NERL&amp;dirEntryId=309417</a></div><div><br /></div><div>USEPA.  2024. National Aquatic Resource Surveys. Indicators: Chlorophyll a. <a href="https://www.epa.gov/national-aquatic-resource-surveys/indicators-chlorophyll" target="_blank">https://www.epa.gov/national-aquatic-resource-surveys/indicators-chlorophyll</a>.</div><div><br /></div><div>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>

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.

Min. Scale: 0

Max. Scale: 0

Default Visibility: true

Max Record Count: 2000

Supported query Formats: JSON, geoJSON, PBF

Use Standardized Queries: True

Extent:

Drawing Info:

HasZ: false

HasM: false

Has Attachments: false

Has Geometry Properties: false

HTML Popup Type: esriServerHTMLPopupTypeAsHTMLText

Object ID Field: OBJECTID

Unique ID Field:

Global ID Field:

Type ID Field:

Fields:
Templates:

Is Data Versioned: false

Has Contingent Values: false

Supports Rollback On Failure Parameter: true

Last Edit Date: 10/9/2024 4:31:56 PM

Schema Last Edit Date: 4/1/2024 8:44:55 PM

Data Last Edit Date: 4/1/2024 8:44:55 PM

Supported Operations:   Query   Query Top Features   Query Analytic   Query Bins   Generate Renderer   Validate SQL   Get Estimates   ConvertFormat