News Release
FOR IMMEDIATE RELEASE – DECEMBER 19, 2025
Renee Bourassa, Communications Director
Interstate Commission on the Potomac River Basin | Rockville, MD
rbourassa@icprb.org | 301.417.4371

A new report on stream health in the Chesapeake Bay watershed shows a slight improvement in recent years but a strong positive trend over the past two decades. 

Chessie BIBI ratings, 2018-2023

A new report from the Interstate Commission on the Potomac River Basin (ICPRB), the organization tasked with assembling and reporting the data, shows a 1.4 percent improvement in overall stream health throughout the Chesapeake Bay watershed over the past six years.

The tracking tool is a Chesapeake basin-wide index of biotic integrity for stream macroinvertebrates, known as Chessie BIBI for short. One way scientists gauge the health of a stream is by figuring out who calls it home. Specifically, how many and what species of benthic macroinvertebrates — the scientific term for creek critters like dragonfly and stonefly larvae — are living at the bottom of a stream. Some creek critters need healthy streams to live while others are more tolerant of poor conditions.

“It would be too expensive to monitor for every possible contaminant in every part of the stream,” explains Dr. Claire Buchanan, director emerita at ICPRB and one of the study’s co-authors.  “The health of the creek critters gives us a good gauge on the overall health of the stream because their numbers show a predictable pattern depending on their sensitivity to pollution. If something is going wrong — or right — they’re going to tell us.”

The Chessie BIBI tracks percent improvement over 6-year intervals to capture the various monitoring schedules across the watershed.

In the past quarter century, Chessie BIBI has seen which translates to almost 15,000 healthier stream miles overall, according to the report. With the new numbers, an estimated two-thirds of the roughly 145,000 stream miles in the Bay watershed now have Chessie BIBI ratings of excellent, good, or fair.

“Significant watershed management has been underway for decades to the credit of all jurisdictions in collaboration and cooperation with federal, state, local governments and non-governmental organizations,” explains Peter Tango, Chesapeake Bay Monitoring Coordinator at the USGS. “Not only do we get to see habitat changes, but the incredible value associated with the work from consistent long-term monitoring and analysis of the bugs shows us that living resources are responding to those habitat changes in a measurable, tangible, and positive way.”

This measurement is part of the Stream Health Goals of the Chesapeake Bay Watershed Agreement, which sets a specific goal for the entire watershed. The 2014 Chesapeake Bay Agreement set a goal to “improve health and function of 10% of stream miles above the 2008 baseline.”

“It is exciting that the partners of the Chesapeake Bay Program could possibly achieve the original 2014 Chesapeake Bay Agreement goal by 2029 if we continue on this trajectory,” remarks Dr. Buchanan.

The Agreement was revised in December 2025 with an eye to the future and a new goal of 3 percent improvement during each interval. While previous intervals surpassed this percentage (4.3 percent and 4.6 percent), the most recent interval fell short at only 1.4 percent. The report notes that data from the most recent interval was impacted by an unusually wet 2018 and 2019 and monitoring gaps due to the COVID pandemic.

“The collection of monitoring data across the watershed is a major achievement, but gaps still remain,” states Dr. Emily Young, a co-author of the report and the habitat and living resources data manager at ICPRB who works in the Chesapeake Bay Program Office. “Some areas have not been monitored in two decades, and a few areas have never been monitored at all. Additional data would help complete the watershed-wide picture.”

In addition to data gaps, improvement is unevenly distributed in the watershed. According to the research, recovery appears to be location dependent, with rural regions showing stronger recovery than heavily populated regions which remain steady from previous years while streams in some agricultural regions are degrading.

“When it comes to streams in the Chesapeake Bay watershed, the biologically rich stay rich and the poor continue to struggle,” describes Rikke Jepsen, an aquatic ecologist at ICPRB and co-author on the report. “This is driving the overall recovery, while the less healthy streams may actually be degrading. It appears that less healthy streams benefit from being close to another stream with a strong, healthy population because they help populate the recovering waterways. This means recovery may be slower in regions that are already struggling.”

ICPRB is currently collecting data for the next Chessie BIBI report, which will cover the next 6-year interval of 2024-2029.

“This couldn’t be done without our partners across all levels, from federal, state, local, and citizen monitoring programs. It just goes to show how working collaboratively across sectors can help improve the Chesapeake Bay and its tributaries, like the Potomac River,” explains ICPRB Executive Director Michael Nardolilli.

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PRESS CONTACT:

Renee Bourassa, Director of Communications and Education
Interstate Commission on the Potomac River Basin | Rockville, MD
rbourassa@icprb.org | 301.417.4371 | www.potomacriver.org

LINKS AND OTHER RESOURCES:

• Report: Stream Health in the Chesapeake Bay Watershed, 2018 – 2023 Update.
• Map: Stream Health in the Chesapeake Bay Watershed, 2018 – 2023 Update (JPG)
• More information: “Chessie BIBI” Index for Streams
• Bioregions of the Chesapeake Bay (JPG)
• Online Map Explorer of the Bioregions of the Chesapeake Bay

The ICPRB is an interstate compact commission established by Congress in 1940. Its mission is to protect and enhance the waters and related resources of the Potomac River basin through science, regional cooperation, and education. Represented by appointed commissioners, the ICPRB includes the District of Columbia, Maryland, Pennsylvania, Virginia, West Virginia, and the federal government.

Click here for a PDF of the News Release: Streams showing slow, but steady, improvement in the Chesapeake Bay watershed >>>

New water supply study; ICPRB hiring interns; winter salt is in the news; and more, in this week’s Potomac News Reservoir – Dec. 11, 2025 >>>

River Report: Flow evening out soon

We’ll soon see the daily fluctuations flatten out at the USGS Point of Rocks gage. The ups and downs of the river’s flow are a result of upstream hydroelectric dam operations to protect American eels. The dams are turned off nightly from mid-September to mid-December during the annual American eel migration downstream. This keeps the eels from getting caught up in dam machinery as they make their way to sea to spawn. As a result, the flows downstream fluctuate in the daily pattern we’ve been seeing for the past few months.

Check out ICPRB’s recent webinar on the fascinating historical and ecological importance of American eels.

Today’s drought monitoring report:

🌊Flow at USGS Point of Rocks gage is 1930 cubic feet per second (cfs). The historical median for today is 5040 cfs.

☀️ According to the Middle Atlantic River Forecast Center, scattered trace amounts of precipitation fell in the western part of the basin over the past 24 hours.

🔮 Up to 0.25 inches of precipitation is expected in the basin over the next 3 days.

Other than a small percentage increase from abnormally dry to moderate drought conditions, the U.S. Drought Monitor map is similar to last week.

ICYMI: New report exposes the vulnerabilities of the Washington metropolitan area’s water supply

According to research by the Interstate Commission on the Potomac River Basin (ICPRB), the region’s water supply could fail to meet the needs of the region as soon as 2030 in the event of an extreme drought.

While most people don’t think twice about where their water comes from — or if it will come at all — when they turn on the tap, new research notes that changing weather patterns and increased water demand are putting a strain on the region’s water supply. This may have dire consequences without strong investment in water infrastructure according to a new report by ICPRB, an organization tasked with producing a report every five years on the region’s water supply.

Read the full press release or watch the webinar >>>

ICPRB Hiring Interns for 2026

We are excited to announce ICPRB has openings for up to two water resources interns for the spring and summer semesters of 2026. The  start and end dates are negotiable, approximately March to August, 2026. Pay is $20/hr. ICPRB is located in Rockville, Maryland.

The primary tasks of the internships are to support ICPRB’s water resources and CO-OP programs, assemble data needed for estimations of unreported water uses, and archive ICPRB photographs and reports.

Applications are due by January 9, 2026. Learn more about the position and how to apply on our Jobs page >>>

Webinar series

Join us for more fascinating webinars in the coming weeks:

• Dec. 18: Webinar: Reconsidering Connectivity: A North Branch Potomac Case Study (Gordon “Mike” Selckmann, Associate Director of Aquatic Biology, ICPRB) [Rescheduled from Dec. 2]

• January 21, 1 – 1:30 pm: Safe Sidewalks, Clean Water: Smart Salting for Residents

• January 23, 1 – 1:30 pm: Community Winter Salt Management in Action

According to research by the Interstate Commission on the Potomac River Basin (ICPRB), the region’s water supply could fail to meet the needs of the region as soon as 2030 in the event of an extreme drought.

ROCKVILLE, MD (December 5, 2025): While most people don’t think twice about where their water comes from — or if it will come at all — when they turn on the tap, new research notes that changing weather patterns and increased water demand are putting a strain on the region’s water supply. This may have dire consequences without strong investment in water infrastructure according to a new report by the Interstate Commission on the Potomac River Basin (ICPRB), an organization tasked with producing a report every five years on the region’s water supply.

The report, 2025 Washington Metropolitan Area Water Supply Study – Demand and Resource Availability Forecast for the Year 2050, shows that the region will have plentiful water most years, but there is an increasing chance — up to about 1 percent in 2030 and up to about 5 percent in 2050 — that there will be water shortages. This is when there is not enough water to meet the demands of the water users while still leaving enough water in the Potomac River to protect the sensitive aquatic habitat below Little Falls Dam.

Actual Washington metropolitan area annual water demand (blue dotted line), ICPRB’s 2025 forecast (blue solid line), with actual and forecasted population (gray dotted line).
(Source: ICPRB)

According to the report, despite exponential growth in the region, overall water use has stayed remarkably stable over the past several decades due to the use of low flow fixtures and appliances. However, the researchers predict an increase in water demand in the coming decades, with a 17 percent increase in water use by 2050.

In addition to more overall use, the river’s flow may be impacted by predicted changes in temperature and precipitation through a process that has been characterized as “hot drought” by ICPRB.

“Results from our study indicate that extreme hydrological droughts may become more severe due to increasing temperatures,” explains Dr. Cherie Schultz, Director of ICPRB’s Section for Cooperative Water Supply Operations on the Potomac.

“A major uncertainty in many regions, including the Potomac, is the response of future stream flow to the competing effects of temperature change and precipitation change. Rising temperatures will tend to decrease flows due to increases in evaporation, while predicted increases in precipitation will tend to increase flows,” continued Dr. Schultz.

“It is changing weather patterns combined with the increase in demand that may be putting the whole system at risk,” states ICPRB Executive Director Michael Nardolilli.

Data center growth is also contributing to the uncertain future of the region’s water supply, both upstream and within the Washington metropolitan area. The study finds that upstream data center water use is expected to grow over time and could become comparable to several established water-using sectors, such as commercial, industrial, and thermoelectric facilities. These estimates are based on grid-connected energy forecasts, which are rapidly evolving as the sector continues to expand. In the Washington metropolitan area, data centers could use as much as 80 million gallons on peak days by 2050. This could signal the growing significance of data centers in the region’s water demand. The report notes that balancing energy, water, regulations, and infrastructure constraints may be needed to strengthen resiliency in this sector. One step forward would be to improve transparency around data center water use.

The majority of the Washington metropolitan area’s water supply is provided by the Potomac River. While most regions have two or more sources of water, the Potomac River is the only source of drinking water for the residents of Washington D.C. and Arlington County.

Two upstream reservoirs, Jennings Randolph and Little Seneca, are available to release water to augment Potomac River flow should the river get too low to meet the region’s demands. In addition, off-Potomac reservoirs, Fairfax Water’s Occoquan Reservoir and WSSC Water’s Patuxent reservoir, are used to partially meet these suppliers’ demands. According to the study, four out of nine modeled scenarios predict that in the event of an extreme drought, the upstream reservoirs will run out of water as early as 2030, indicating that short-term measures should be taken to improve reliability.

Some short-term solutions are already in the works. Improvements in ICPRB’s river flow forecasts can help water resource planners better predict when to release water from upstream reservoirs. A water reuse project recently announced by DC Water, dubbed Pure Water DC, aims to create a more resilient water source for residents of the District. Two drinking water reservoirs currently in the planning stages, Loudoun Water’s Milestone Reservoir (expected operational by 2028) and Fairfax Water’s Edgemon Reservoir (expected operational by 2040), were already included in the report’s calculations.

The U.S. Army Corps of Engineers, Baltimore District, initiated a D.C. Metropolitan Area Backup Water Supply Feasibility Study last fall which could lead the way to possible long-term solutions. However, with federal funding issues hanging in the balance, it is unclear when that study will be completed.

“For nearly 170 years, the Washington Aqueduct has been committed to executing its critical mission to produce safe, reliable, and high-quality drinking water for approximately one million citizens living, working, or visiting the National Capital Region,” said Washington Aqueduct General Manager Rudy Chow. “Increased water resiliency standards are a vital part of our commitment to public health and safety, national security and the wellbeing of local populations. We are in close collaboration with our regional utility partners as we continue our ongoing Washington D.C. Metropolitan Area Backup Water Supply Feasibility Study, aimed at developing coordinated and implementable solutions that ensure abundant water supply, including the identification of a secondary water source and additional water storage capability.”

“We can no longer ignore the fact that parts of the DC region have only one source of drinking water – the Potomac River – and just a one-day back-up of water supply. Today’s release of the 2025 Washington Metropolitan Area Water Supply Study highlights the need to expedite the study so that we can reduce the vulnerability of the DC region from a cutoff of drinking water because of drought or contamination events (both accidental and deliberate),” explained Nardolilli.

“This report confirms the need for innovative and cooperative approaches, as well as funding, to secure the water supply for our region,” said WSSC Water General Manager and CEO Kishia L. Powell. “The Potomac River has provided the vast majority of the region’s drinking water for generations. But climate pressures and growing demand will impact our ability to meet the region’s needs in just a few years. This report makes clear that we need to continue with substantial investments to safeguard public health, enhance reliability and resiliency, and ensure the long-term economic vitality of the region.”

An earlier study released by ICPRB found that a significant water supply disruption could result in losses of almost $15 billion in gross regional product and hundreds of millions in tax losses, all within the first month.

“For nearly 50 years Fairfax Water, WSSC Water, the Washington Aqueduct and ICPRB have been working together to ensure adequate water supply for the Washington Metropolitan Region now and into the future” said Fairfax Water General Manager and CEO Jamie Bain Hedges. “This study further advances our collective mission to supply life’s most essential service for decades to come.”

The water supply study released today is conducted every five years by the Section for Cooperative Water Supply Operations on the Potomac (CO-OP) of the Interstate Commission on the Potomac River Basin (ICPRB) on behalf of the three major water suppliers: Fairfax Water, WSSC Water, and the Washington Aqueduct. This is the first year that the study has explored the impacts of data centers on the water supply.

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Click here for a PDF of News Release: New report exposes the vulnerabilities of the Washington metropolitan area’s water supply>>>

A factsheet summary of the report is also available >>>

PRESS CONTACT:

Renee Bourassa, Director of Communications and Education
Interstate Commission on the Potomac River Basin | Rockville, MD
rbourassa@icprb.org | 301.417.4371 | www.potomacriver.org
Questions regarding Washington Aqueduct operations or feasibility study can be sent to NAB-PAO@usace.army.mil

LINKS AND OTHER RESOURCES:

• Full report: 2025 Washington Metropolitan Area Water Supply Study – Demand and Resource Availability Forecast for the Year 2050
• Summary: Factsheet
• Map – Figure 2-1: Washington metropolitan area water supplier service areas and existing and planned water supply resources. (full basin)
• Map – Figure 2-2: Water supplier service areas in the Washington metropolitan area, existing and anticipated as of 2025. (scaled to Washington metropolitan region)

The ICPRB is an interstate compact commission established by Congress in 1940. Its mission is to protect and enhance the waters and related resources of the Potomac River basin through science, regional cooperation, and education. Represented by appointed commissioners, the ICPRB includes the District of Columbia, Maryland, Pennsylvania, Virginia, West Virginia, and the federal government.