City Cast DC logo

Urban Almanac: Finding Intel in Rainwater

Posted on June 5, 2023   |   Updated on September 30, 2025
Kaela Cote-Stemmermann

Kaela Cote-Stemmermann

The U.S. Naval Research Lab, where the magic happened. (Mr.TinMD/flickr)

The U.S. Naval Research Lab, where the magic happened. (Mr.TinMD/flickr)

Did you know that our environment — birds, trees, even the rain — can betray us to talented spies? Neither did I, until I went to the Spy Museum.


In 1949, the Navy secretly collected rainwater at a station in Washington, D.C. (and also in Kodiak, Alaska) that they believed to have fallen from clouds that originated in the Soviet Union. As part of “Project Rain Barrel,” scientists at the Naval Research Laboratory analyzed the droplets to see if they had debris from nuclear weapons tests.

“A fallout of fission products from the air was detected in Kodiak, Alaska, Sept. 9, [1949] by a gamma ray ground counter and in Washington, D.C. by filter paper on the same day,” they concluded.

“Top secret” documents from 1949. (National Security Archive/George Washington University)

“Top secret” documents from 1949. (National Security Archive/George Washington University)

The National Security Archive says the project “was critically important to forming the scientific consensus about the nature of the Joe-1 test,” which was the USSR’s first nuclear bomb test.

Share article

Hey DC

Get smart about D.C. with our news roundup and analysis.

Can't subscribe? Turn off your ad blocker and try again.

Urban Almanac

See All
Urban AlmanacMarch 19

How To Start an Urban Garden In DC

Even in the city, you can grow your own food. Here’s how to make use of even the tiniest spaces, whether you’re designing your community...

Garden beds at Bruce Monroe Community Garden in Columbia Heights.
Urban AlmanacSeptember 4, 2025

How to Experience the 2025 National Book Festival in DC

This Saturday, Sept. 6, the Library of Congress is throwing a party for book lovers: the 25th annual National Book Festival.

The flyer for the National Book Festival.
Urban AlmanacJuly 30, 2025

How to Manage and Stop the Spread of Invasive Lanternflies

The invasive spotted lanternfly has returned to the Washington, D.C. region this summer. Here's what you need to know about why it spread...

A person holds an adult spotted lanternfly found in Huntington, Indiana, on Aug. 17, 2022.
Urban AlmanacJuly 31, 2024

Does Extreme Heat Cause Sudden Branch Drop Syndrome?

After the tragic death of a woman in D.C., local officials are investigating if extreme heat contributes to Sudden Branch Drop Syndrome.

After the tragic death of a woman in D.C., local officials are investigating if extreme heat contributes to Sudden Branch Drop Syndrome. (jiamiao lin/Getty Images)
Urban AlmanacJune 12, 2024

How To Forage in the DMV

An ancient foraging proverb says, “there are old foragers and there are bold foragers, but there are no old, bold foragers!”

Beautiful and edible chickweed. (mikroman6/Getty Images)
Urban AlmanacMay 8, 2024

Maryland Renames Snakehead Fish In Hopes of Increasing Demand

Maryland is renaming the invasive snakehead fish in hopes of getting more people to eat it. The snakehead fish will soon be known as the...

An invasive Northern snakehead caught in the tidal marshes of Southeast Virginia.
Urban AlmanacApril 17, 2024

How To Water Your Street Trees

One critical piece of this is to water your street trees, especially if you have a young tree outside your house or apartment.

A well established sidewalk tree.
Urban AlmanacApril 3, 2024

How To View The Solar Eclipse In DC

A solar eclipse occurs when the moon passes between the sun and Earth, blocking out our precious sunlight for a few rare minutes.

The sky during a full solar eclipse

The latest in DC

The DC DispatchMay 15

Pirro Says She Will Prosecute Parents of Kids Participating in "Teen Takeovers"

U.S. Attorney Jeanine Pirro said parents could face fines or up to six months of jail time.

US Attorney for the District of Columbia Jeanine Pirro and US Acting Attorney General Todd Blanche. (Annabelle Gordon/AFP via Getty Images)
ObsessedMay 14

Eating Facebook Marketplace Food for An Entire Weekend in DC

From tamales to seafood boils, the viral Facebook Marketplace food trend is hitting the DMV.

Nothing to see here, just some Facebook food delusions. (Kaela Cote-Stemmermann/City Cast DC)
AnnouncementsMay 12

Kaela Cote-Stemmermann Is City Cast DC’s New Food and Culture Reporter

City Cast DC is undergoing an unprecedented expansion of its local newsroom, hiring a team of journalists to create original reporting ab...

The DC DispatchMay 12

"Downright scandalous:" Inside the NSFW text messages that got a top D.C. police official put on leave

An internal report shows ex-executive assistant chief Andre Wright repeatedly sent crude texts and mocked colleagues.

An internal report shows ex-executive assistant chief Andre Wright repeatedly sent crude texts and mocked colleagues. (Saul Loeb/AFP via Getty Images)
The DC DispatchMay 5

Police Chief: 13 Top Officials Face Termination Amid Crime Stats Scandal

Jeffery Carroll also confirmed the restructuring of the department.

Interim MPD Chief of Police Jeffery Carroll.
The DC DispatchMay 4

Multiple D.C. Police Leaders Face Termination Over Crime Data Manipulation

The changes could constitute a sweeping restructuring of department leadership.

Metropolitan Police Department outside of Nationals Park on August 15, 2025. (Kayla Bartkowski/Getty Images)
AnnouncementsMay 4

We're launching two new newsletters

Sign up now to get the big stories Washington is talking about and our can't-miss guide to food and culture.

DC, ExplainedMay 4

The Obama musical returns Washingtonians to an old, hopeful DC

This raunchy love letter to 2008 D.C. by a former Obama campaign staffer left us weeping with laughter and nostalgia.

TJ Wilkins starring as Barack Obama sings “How Black Is Too Black?” (Courtesy of “44”)