NCRN Water Quality

Updated 2025-06-05

Disclaimer

This visualizer tool allows users to explore and analyze water quality data. It uses data published on the National Park Service (NPS) platform known as IRMA Data Store:
DataStore - National Capital Region Network Stream Water Quality Data Package - cumulative through 2024

This visualizer tool operates using R Shiny code. A static copy of the application source code is available on NPS IRMA Data Store:
DataStore - National Capital Region Network Water Visualizer (R Shiny application)

The development version of the source code is available at:
https://github.com/NCRN/NCRNWaterViz/tree/ncrn_refactor

Introduction

The National Park Service preserves unimpaired the natural and cultural resources and values of the National Park System. The National Captial Region Inventory and Monitoring Network (NCRN) is part of the National Park Service Inventory and Monitoring Division, which conducts science in National Parks. NCRN conducts science, like water quality monitoring, in the National Park Service's National Capital Region, which includes parts of Virginia, West Virginia, Maryland, and the District of Columbia, USA.

Methods

Click here to view or download NCRN's water quality methods

Sampling locations

As of January 2025, NCRN monitors water quality at 37 sites in ten National Parks in the National Capital Region. NCRN has added and removed sites since 2005. Tables 2,3, and 4 in NCRN's Water Chemistry and Quantity Monitoring Protocol details changes to sampling sites through time.

Each NCRN water quality site meets these criteria:

Approved by the Park
1^st - 4^th Strahler order freshwater stream
Wadeable
Non-tidal
Has at least 250 meters of stream reach in Park boundaries
Is positioned downstream in its reach (e.g., before a confluence or near the Park boundary)
Safe from hazards like depth, velocity, obstructions
Perrenial; has sufficient year-round water depth and flow to collect a discharge measurement
Safe, reasonable, and legal to access without undue travel or easement

Sampling frequency

NCRN began monitoring water quality in 2005 and monitoring is ongoing. NCRN has changed sampling frequency since 2005. Section 2.5 and 2.6 in NCRN's Water Chemistry and Quantity Monitoring Protocol details changes to sampling frequency.

Since October 2017, NCRN has monitored water quality bi-monthly (i.e., once every two months) at each site

From October 2013 to October 2017, NCRN monitored water quality quarterly (i.e., once every three months) at each site

From May 2005 to October 2013, NCRN monitored water quality monthly (i.e., once each month) at each site

Parameters

As of January 2025, NCRN monitors 15 numeric water quality parameters. NCRN also collects text and categorical data (e.g., epilithic algae color) which are present in the full dataset but absent from this website. Over time, NCRN has added and removed parameters from its monitoring protocol. Table 5 in NCRN's Water Chemistry and Quantity Monitoring Protocol details changes to sampling parameters.

Water temperature
Air pressure (i.e. barometric pressure)
Dissolved Oxygen concentration (DO concentration mg/L)
Dissolved Oxygen saturation (DO saturation %)
Specific Conductance
Conductivity
Salinity
pH
Acid Neutralizing Capacity (ANC)
Total Nitrogen concentration (TN)
Total Phosphorus concentration (TP)
Discharge
Wetted width (stream width across stream crossection where discharge was measured)
Stream Velocity (average water velocity across stream crossection where discharge was measured)
Depth (average water depth across stream crossection where discharge was measured)

Data quality

Completeness
- NCRN's active sites and parameters are included in this website
- Retired monitoring sites were excluded from this website. NCRN retires sites when they stop fitting our protocol, such as when a stream that used to flow year-round becomes seasonally dry.
- Retired monitoring parameters were excluded from this website. NCRN retires parameters as needed. For example, NCRN stopped measuring Total Dissolved Nitrogen concentration in 2018 and immediately began collecting Total Nitrogen concentration instead.
- Categorical and text parameters, like descriptions of stream stage and epilithic algae, were excluded from this website
- NCRN's full water quality dataset, including retired sites and parameters, is available for download from NPS DataStore
Accuracy
- NCRN calibrates field instruments (e.g., YSI ProDSS handheld) to manufacturer specifications before each site visit
- A certified, third-party laboratory (UMCES Appalachian Lab) measures NCRN's water chemistry results (ANC, TP, TN)
Validity
- NCRN's data governance procedures ensure measurements, parameters, units, and location attributes are consistent through time and within-and-among sites

Bibliography

References

Allan, J. D. 1995. Stream Ecology: Structure and Function of Running Waters. Chapman and Hall, New York.

District Department of the Environment. 2010. Notice of final rulemaking: triennial review of the District of Columbia's Water Quality Standards. Pages 009129-009160, Washington, DC.

EPA. 2000a. Ambient Water Quality Criteria Recommendations: Information Supporting the Development of State and Tribal Nutrient Criteria for Rivers and Streams in Nutrient Ecoregion IX. EPA 822-B-00-019, US Environmental Protection Agency, Washington, DC.

Heinz Center. 2002. The state of the Nation's ecosystems: Measuring the lands, waters, and living Resources of the United States.

Morgan, R. P., K. M. Kline, and S. F. Cushman. 2007. Relationships among nutrients, chloride and biological indices in urban Maryland streams. Urban Ecosystesm 10:153-166.

State of Maryland. 2010. Title 26 Department of the Environment, Subtitle 08 Water Pollution, Chapter 02 Water Quality, Authority: Environment Article, 9-303.1, 9-313-9-316, 9-319, 9-320-9-325, 9-327, and 9-328, Annotated Code of Maryland, The State of Maryland, editor. 26.08.02. The State of Maryland, Annapolis, MD.

State of West Virginia. 2011. Title 47 Legislative rule, Department of Environmental Protection, Water Resources, Series 2: Requirements governing water quality standards.

Stednick, J. D. and D. M. Gilbert. 1998. Water quality inventory protocol: riverine environments. NPS/NRWRD/NRTR-98/177, National Park Service, Servicewide Inventory and Monitoring Program, Fort Collins, CO.

U.S. Geological Survey. 1980. Surfacewater. page 130, U.S. Geological Survey, editor. National handbook of recommended methods for water-data acquisition. U.S. Geological Survey.

Virginia State Water Control Board. 2011. Virginia Water Quality Standards. State of Virginia, editor. 9 VAC 25-260.

Weeks, D., D. Vana-Miller, M. Norris, and A. Banasik. 2007. Water Resources Stewardship Report: Monocacy National Battlefield. National Park Service, Fort Collins, CO.