Interstate Commission on the Potomac River Basin - ICPRB

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Interstate Commission on the Potomac River Basin - ICPRB Protecting and preserving the Potomac through science and cooperation. The federal government also is a member.

Authorized by an Act of Congress in 1940, the Interstate Commission on the Potomac River Basin is an advisory, non-regulatory interstate compact agency of the Potomac basin states of Maryland, Pennsylvania, Virginia, West Virginia, and the District of Columbia. ICPRB was formed in response to extreme pollution levels that required a regional, cooperative response by all the jurisdictions. In 1970, amendments to the compact empowered ICPRB to address not just pollution issues, but water resources and related land issues by two or more jurisdictions. The river’s water quality has in many ways vastly improved, but threats to the river (population increases, land use change and the growth of impervious surface, chemical contaminants, and nutrient and sediment enrichment) require regional attention. The regional efforts needed to address these challenges help to inform ICPRB’s Strategic Plan. Our mission is to protect and enhance the waters and related resources of the Potomac River basin through science, regional cooperation, and education. Considered the “Nation’s River,” for more than six million basin residents, the river plays an important role in the lives of all. Through regional cooperation and partnerships, ICPRB is protecting the river and improving the quality of life in the watershed. ICPRB jurisdictions are represented by appointed Commissioners. Commission staff includes professionals from various disciplines, including environmental engineers, aquatic ecologists, biologists, and professionals in communications. One staff member works directly with the Chesapeake Bay Program out of their Annapolis, Maryland, office.

🚨New map alert 🚨How are everyone's favorite underwater dwellers, benthic macroinvertebrates, faring across the Bay water...
10/16/2026

🚨New map alert 🚨

How are everyone's favorite underwater dwellers, benthic macroinvertebrates, faring across the Bay watershed? Take a deep dive into the data on your local stream's health, as indicated by the number and species of critters living at the bottom, through a newly-updated interactive online map, the Chessie BIBI Map Explorer (link in the comments).

Tracking this index, the Chesapeake basin-wide index of biotic integrity for stream macroinvertebrates (aka Chessie BIBI), is one way that scientists can gauge the health of a stream. A 2025 ICPRB report showed a 1.4% improvement in overall stream health throughout the Chesapeake Bay watershed over the past six years!

River Report: Isaias gave us a good soakingAfter only a few days, ICPRB suspended daily Drought Monitoring when the remn...
10/15/2026

River Report: Isaias gave us a good soaking

After only a few days, ICPRB suspended daily Drought Monitoring when the remnants of Isais blew through and increased the river’s flow.

During the storm the region received 1 - 4 inches of rain, with the majority in the western part of the watershed.

🗺️ After weeks of stagnant conditions, we finally got some movement in the U.S. Drought Monitor map today. The area in Moderate Drought dipped to 9% while 40% of the watershed remains in abnormally dry conditions.

🌊 After the storm, flow at the USGS gage at Point of Rocks went from near the 25th percentile of 1,500 cubic feet per second (cfs) to 26,300 cfs, which is considered Extremely Above normal.

📈 Due to the recent storm, our rainfall deficit has decreased to only 3.4 inches below normal for the past year.

☔ 0.0 - 1.25 inches of rain is expected over the next week. (MARFC)

Thank you to Montgomery County DEP for hosting today’s H2O Summit! With a theme of “Catching it at the Source!”, present...
10/13/2026

Thank you to Montgomery County DEP for hosting today’s H2O Summit!

With a theme of “Catching it at the Source!”, presentations focused on innovative projects, community action, and other ways we can reduce water pollution at the source, including:

🧂 Reducing winter salt use
🌲 Planting trees
🥤 Pickup trash
💩 Pickup pet waste

What happens to salt on the ground after the snow melts each winter? Walk with us along the Anacostia to discover the im...
10/12/2026

What happens to salt on the ground after the snow melts each winter? Walk with us along the Anacostia to discover the impact of winter salt to our waterways, learn more about the Springsong Museum project focusing on local legend Rachel Carson, and discuss how we can all take action to create a cleaner, healthier future.

Staff from the Izaak Walton League of America’s Salt Watch Program will guide us as we test the water for chloride, a marker of road salt pollution. This walk combines community science and environmental education, giving you the tools to make a difference!

The details:
🗓 Saturday, November 7
🕙 10:00 am
📍 Burnt Mills East Park, Silver Spring, MD
🎟 RSVP for free on eventbrite

https://www.eventbrite.com/e/walk-in-the-woods-lets-be-smart-about-winter-salt-ft-springsong-museum-tickets-1996451326661?aff=oddtdtcreator&keep_tld=true

🎉 Good news in today’s   report:Yesterday’s average daily flow at the USGS Point of Rocks gage was 2,140 cubic feet per ...
10/12/2026

🎉 Good news in today’s report:

Yesterday’s average daily flow at the USGS Point of Rocks gage was 2,140 cubic feet per second (cfs), above the 2,000 cfs threshold for CO-OP daily drought monitoring. Flow has continued to rise, with today’s flow estimated at 2,980 cfs based on recently available real-time data. CO-OP is therefore suspending its daily drought monitoring and reporting.

☔️ According to the Middle Atlantic River Forecast Center, widespread rainfall occurred across the Potomac basin during the past 24 hours, with estimated totals generally ranging from 0.75 to 2.5 inches and locally higher amounts of 2.5 to 4 inches.

🔮 Little additional rainfall is forecast over the next three days. The Weather Prediction Center’s seven-day outlook indicates generally less than 0.25 inches of additional precipitation across most of the basin through October 19, with locally higher amounts possible in the upper basin.

We will continue to monitor river conditions and resume daily reporting if needed.

Thank you to the organizations and water suppliers for your continued support and cooperation.

10/11/2026

The report for Oct. 11, 2026:

☔️ The Potomac basin received approximately 0.25–1.5 inches of rain over the past 24 hours, with locally higher amounts up to 2 inches in the southwestern portions of the basin.

🔮 Widespread rainfall of 1–1.5 inches is forecast over the next three days, with localized totals reaching 2 inches. (MARFC)

🌊 Even with all that rain, flow at Point of Rocks appears to be still low at 1,580 cubic feet per second. (USGS)

Today’s   report:☀️ No rainfall was observed over the past 24 hours in the Potomac basin upstream of Little Falls, Maryl...
10/10/2026

Today’s report:

☀️ No rainfall was observed over the past 24 hours in the Potomac basin upstream of Little Falls, Maryland.

🔮 1 to 3 inches of rain is expected over the next three days.

🌊 Flow at USGS Maryland-Delaware-DC Water Science Center Point of Rocks gage is 1,540 cubic feet per second (cfs).

📈 The graph shows river level probabilities over the next 10 days. (MARFC)

The Water Supply Outlook for October 2026 has been published (link in the comments). The Water Supply Outlook is publish...
10/09/2026

The Water Supply Outlook for October 2026 has been published (link in the comments). The Water Supply Outlook is published each month from April to October.

In summary:
✅ There is a near-normal probability of releases from the Washington metropolitan area’s back-up water supply reservoirs for the end of 2026 fall season.

📊 U.S. Geological Survey (USGS) data show variable groundwater conditions across the Potomac River basin with some improvements in the past month but with below-normal groundwater levels persisting at several monitoring wells. Streamflow is currently within the normal range for this time of year.

🍂 Drought conditions have improved since September but remain across portions of the basin. As of October 6, 23% of the basin was in moderate drought (D1), and 36% was abnormally dry (D0).

👀A Drought Watch for the metropolitan Washington region remains in effect. Reservoirs remain near full.

At present, Potomac River flow is sufficient to meet metropolitan area water demands without upstream reservoir augmentation.

The   report for Friday, 10/9/26: ☂ During the last 24 hours, the US National Weather Service Middle Atlantic River Fore...
10/09/2026

The report for Friday, 10/9/26:

☂ During the last 24 hours, the US National Weather Service Middle Atlantic River Forecast Center reported no significant observed rainfall in the Potomac River Basin.

⛈ They predict 1.0 to 1.75 inches of rainfall during the next three days, with a similar seven-day forecast total.

📉 Recent estimated flow at the USGS Science in Maryland-Delaware-District of Columbia streamgage at Point of Rocks: 1560 cubic feet per second.

🐟 Special conditions: Intra-daily flow fluctuations at Potomac River gages, including Point of Rocks, are occurring due to upstream dam operations associated with eel passage.

The   report for Oct. 8, 2026:Meteorologists are calling for “a good soaking rain” on Sunday, due to Tropical Storm Isai...
10/08/2026

The report for Oct. 8, 2026:

Meteorologists are calling for “a good soaking rain” on Sunday, due to Tropical Storm Isaias passing through. However, the exact path of the storm is still uncertain.

🗺️ The numbers in today’s U.S. Drought Monitor Map haven’t budged much from last week, with 23% of the watershed in Moderate Drought and 36% abnormally dry.

🌊 Flow at the USGS Science in Maryland-Delaware-District of Columbia gage at Point of Rocks is near the 25th percentile for this time of year.

☔ Up to 0.5 inches of rain is expected over the next 3 days with widespread rainfall totaling 1 - 2 inches over the next week. (US National Weather Service Middle Atlantic River Forecast Center)

🍂 How did this summer’s drought impact leaf-peeping season? Most likely we’ll see a quick color change this year. So, plan accordingly. There are ideas for day trips, train trips, new parks, and more, in the articles featured in today's newsletter (link below).

🐟 Why are we seeing the big daily fluctuations in flow? Eels, of course! Upstream dams are turned off nightly from mid-September to mid-December during the annual American eel migration downstream to protect them during their journey, resulting in the ups and downs we see in flow.

https://mailchi.mp/9c979a51e49c/potomac-news-reservoir-4793456

Address

401 N. Washington Street, Ste 300
Rockville, MD
20850

Opening Hours

Monday 8am - 4pm
Tuesday 8am - 4pm
Wednesday 8am - 4pm
Thursday 8am - 4pm
Friday 8am - 4pm

Telephone

+13019841908

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