Land Prioritization Map
Conserving land to protect drinking water
Introduction
The Land Prioritization Mapping Project aims to assist land conservation organizations in prioritizing specific parcels of land in the Potomac River basin to obtain the most drinking water quality benefits.
Eight drinking water suppliers, all members of the Potomac River Basin Drinking Water Source Protection Partnership (DWSPP), collaborated to rank land parcels to protect drinking water quality. The project area encompassed the non-tidal Potomac basin above the DC metro drinking water supply intakes, an area of approximately 7.5 million acres. The parcels are ranked from high priority for conservation to low priority for conservation. There are a total of 621 parcels comprising 3,737 acres of high-priority land in the project area. The Interstate Commission on the Potomac River Basin completed the technical work.
Download the flyer , the technical memo or visit the Land Prioritization website to get more information on the project and the land parcels. The map below shows an overview of the high and low rated parcels. Contact ICPRB for the GIS layer that can provide more detailed information on each parcel.
Project Objective Statement
The stakeholder-developed objective statement for the prioritization scheme was to rank parcels to protect drinking water quality and their potential to degrade long-term water quality. The prioritization metrics were selected and the methodology was executed in order to achieve this objective.
The question: Which parcels of land in the Potomac River basin are the most beneficial to drinking water?
Map of Priority Parcels
This map was the product of eight drinking water suppliers asking, "Which parcels of land in the Potomac River basin are the most beneficial to drinking water?"
The resulting project, the Land Prioritization Mapping for Protecting Drinking Water Quality Project , prioritized land parcels for conservation from a drinking water source protection perspective in the Potomac basin. Higher-priority parcels are shown in purple. Lower-priority parcels are shown in green.
This map shows a rough overview of the parcels. Contact ICPRB for the GIS mapping layer that can provide more detailed information on your area of interest.
Priority Level for Conservation
Final Product: Cumulative Metrics
Metrics
Within the project area, agricultural and forested lands, as well as riparian areas protected by county ordinance, were considered “opportunity areas” for prioritization. Land parcels were prioritized using seven metrics. Six metrics were equally weighted, while the seventh metric, karst transmissivity, received half the weight of the other metrics. The metrics and corresponding rationale statements include:
- Distance from Waterways
- Distance from Surface Water Intake Weighted by 24-Hour Travel Time
- Distance from Urban Areas
- Karst Transmissivity
- Future Land Use (Year 2025)
- Preserving Existing High-Quality Streams
- Buffer Regulations
More information on each metric can be found below:
Distance from Waterways
Areas closer to the waterway are more likely to impact downstream drinking water quality.
Distance from Waterways
Distance from Surface Water Intake Weighted by 24-Hour Travel Time
Areas closer to intake locations throughout the basin are more likely to impact drinking water quality. In addition, areas closer to the DC metro utilities may potentially impact larger populations in a shorter amount of time.
Distance to Intakes with Travel Zones
Distance from Urban Areas
Areas closer to urban areas are more likely to be impacted by urban land use activities like winter salt applications and are at greater risk of spills at road-stream crossings.
Distance from Urban Areas
Karst Transmissivity
Areas with higher transmissivity are higher priority as they convey contaminants more readily.
Karst (Ranked by Transmissivity)
Future Land Use (Year 2025)
Protecting lands expected to be forested or agricultural in 2025 are given priority to minimize the impacts of future urbanization.
Future Land Use (2025)
Preserving Existing High-Quality Streams
Areas close to high-quality streams are given priority to protect these resources.
Distance from High Quality Streams
Buffer Regulations
Riparian areas in counties without stream buffer regulations are prioritized as there is not an existing regulatory effort for protection, leaving them more vulnerable to activities that may impact downstream drinking water quality.
Buffer Regulations
Video Presentation
On December 1, 2020, Heidi Moltz of ICPRB gave the following presentation at the virtual ICPRB Business Meeting:
Land Prioritization Mapping for Protecting Drinking Water Quality
Acknowledgments
Stakeholder engagement was essential in developing the land prioritization scheme to ensure that the final products reflect the source water protection priorities of the participating water utilities and are readily available for implementation by land conservation groups, Potomac basin jurisdictions, and other interested parties. ICPRB staff would like to thank all those that have contributed to this effort.
ICPRB Project Team
In alphabetical order
- Renee Bourassa, M.S.
- Christina Davis, Ph.D., P.E.
- Heidi Moltz, Ph.D.
- Andrea Nagel, M.S.
Funded By
with support from (in alphabetical order)
GIS Layer
The Geodatabase GIS Mapping file is available by contacting ICPRB .
Attribution
It is requested that any use of the tool be attributed to ICPRB and our sponsors via this suggested citation: Interstate Commission on the Potomac River Basin. Land Prioritization Mapping for Protecting Drinking Water Quality. https://www.potomacdwspp.org/priority-issues/watershed-protection/land-prioritization-mapping-for-protecting-drinking-water-quality/
