[1]

European Parliament and Council of the European Union. 2000. Directive 2000/60/EC establishing a framework for Community action in the field of water policy. Official Journal of the European Communities. OJ L 327, 22.12.2000. pp. 1–73 https://eur-lex.europa.eu/eli/dir/2000/60/oj/eng

[2]

U.S. Congress. 1972. Federal Water Pollution Control Act (commonly referred to as the Clean Water Act). Washington, DC: U.S. Government Publishing Office, GovInfo. www.govinfo.gov/app/details/COMPS-2989

[3]

United States Environmental Protection Agency. 2026. National Pollutant Discharge Elimination System (NPDES). Last updated February 20, 2026. U.S. EPA, Washington, DC. www.epa.gov/npdes

[4]

European Commission. 2003. Common Implementation Strategy for the Water Framework Directive (2000/60/EC): Guidance Document No. 7, Monitoring under the Water Framework Directive. European Commission, Luxembourg. https://circabc.europa.eu/sd/a/63f7715f-0f45-4955-b7cb-58ca305e42a8/Guidance%20No%207%20-%20Monitoring%20%28WG%202.7%29.pdf

[5]

European Commission. 2003. Common Implementation Strategy for the Water Framework Directive (2000/60/EC): Guidance Document No. 4, Identification and Designation of Heavily Modified and Artificial Water Bodies. European Commission, Luxembourg. https://circabc.europa.eu/sd/a/f9b057f4-4a91-46a3-b69a-e23b4cada8ef/Guidance%20No%204%20-%20heavily%20modified%20water%20bodies%20-%20HMWB%20%28WG%202.2%29.pdf

[6]

European Parliament and Council of the European Union. 2013. Directive 2013/39/EU amending Directives 2000/60/EC and 2008/105/EC as regards priority substances in the field of water policy. Official Journal of the European Union. OJ L 226, 24.8.2013. pp. 1–17. https://eur-lex.europa.eu/eli/dir/2013/39/oj/eng

[7]

European Parliament and Council of the European Union. 2008. Directive 2008/105/EC on environmental quality standards in the field of water policy, amending and subsequently repealing Council Directives 82/176/EEC, 83/513/EEC, 84/156/EEC, 84/491/EEC and 86/280/EEC, and amending Directive 2000/60/EC. Official Journal of the European Union. OJ L 348, 24.12.2008. pp. 84–97 https://eur-lex.europa.eu/eli/dir/2008/105/oj/eng

[8]

European Commission. 2005. Common Implementation Strategy for the Water Framework Directive (2000/60/EC): Guidance Document No. 13, Overall Approach to the Classification of Ecological Status and Ecological Potential. European Commission, Luxembourg. https://circabc.europa.eu/sd/a/06480e87-27a6-41e6-b165-0581c2b046ad/Guidance%20No%2013%20-%20Classification%20of%20Ecological%20Status%20%28WG%20A%29.pdf

[9]

European Commission. 2019. Report from the Commission to the European Parliament and the Council on the implementation of the Water Framework Directive (2000/60/EC) and the Floods Directive (2007/60/EC). COM(2019) 95 final. European Commission, Brussels. https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=COM:2019:95:FIN

[10]

United States Environmental Protection Agency. 2026. Summary of the Clean Water Act. Last updated February 23, 2026. U.S. EPA, Washington, DC. www.epa.gov/laws-regulations/summary-clean-water-act

[11]

United States Geological Survey. 2026. Water Data for the Nation. U.S. Geological Survey, Reston, VA. Accessed April 27, 2026. https://waterdata.usgs.gov/

[12]

United States Environmental Protection Agency. 2026. National Aquatic Resource Surveys. Last updated February 12, 2026. U.S. EPA, Washington, DC. www.epa.gov/national-aquatic-resource-surveys

[13]

United States Environmental Protection Agency. 2025. Background of the national aquatic resource surveys. Last updated September 5, 2025. U.S. EPA, Washington, DC. www.epa.gov/national-aquatic-resource-surveys/background-national-aquatic-resource-surveys

[14]

United States Geological Survey. 2014. About the National Water-Quality Assessment (NAWQA) Program. Last modified October 28, 2014. U.S. Geological Survey, Reston, VA. https://water.usgs.gov/nawqa/about.html

[15]

United States Environmental Protection Agency. 2025. Water Quality Standards Handbook. U.S. EPA, Washington, DC. (Accessed April 27, 2026). www.epa.gov/wqs-tech/water-quality-standards-handbook

[16]

United States Environmental Protection Agency. 2026. Integrated Reporting Memoranda under CWA Sections 303(d), 305(b), and 314. Last updated January 12, 2026. U.S. EPA, Washington, DC. www.epa.gov/tmdl/Integrated%20Reporting%20Guidance%20under%20CWA%20Sections%20303%28d%29%2C%20305%28b%29%20and%20314

[17]

United States Environmental Protection Agency, Office of Inspector General. 2026. Reports OIG. U.S. EPA, Washington, DC. (Accessed April 27, 2026). www.epa.gov/office-inspector-general/reports-oig

[18]

United States Geological Survey. 2010. The national water-quality assessment program—science to policy and management. Version June 30, 2010. U.S. Geological Survey, Reston, VA. https://water.usgs.gov/nawqa/xrel.pdf

[19]

Li L, Knapp JLA, Lintern A, Ng GHC, Perdrial J, et al. 2024. River water quality shaped by land-river connectivity in a changing climate. Nature Climate Change 14(3):225−237

doi: 10.1038/s41558-023-01923-x
[20]

Zhi W, Baniecki H, Liu J, Boyer E, Shen C, et al. 2024. Increasing phosphorus loss despite widespread concentration decline in US rivers. Proceedings of the National Academy of Sciences of the United States of America 121(48):e2402028121

doi: 10.1073/pnas.2402028121
[21]

Zhi W, Klingler C, Liu J, Li L. 2023. Widespread deoxygenation in warming rivers. Nature Climate Change 13(10):1105−1113

doi: 10.1038/s41558-023-01793-3
[22]

United States Environmental Protection Agency. 2025. Overview of Total Maximum Daily Loads (TMDLs). Last updated July 2, 2025. U.S. EPA, Washington, DC. www.epa.gov/tmdl/overview-total-maximum-daily-loads-tmdls

[23]

Li B, Li B, Han Y, Li Q, Liang C, et al. 2025. Rational design of porphyrin-based ionophores for enhanced perchlorate selectivity in ion selective electrodes: application to fireworks wastewater analysis. Energy & Environment Nexus 1:e009

doi: 10.48130/een-0025-0007
[24]

Zhang D. 2025. Establishing a nation-wide eco-environment monitoring network for sustainable governance. Environmental Science and Ecotechnology 26:100585

doi: 10.1016/j.ese.2025.100585