Answer Man recounts putrid story lurking under D.C.

I understand that Constitution Avenue was paved over a body of water called "Tiber Creek." What can you tell me about this creek?

-- L. Totty

Answer Man is sad to report that in its final years, Tiber Creek was not a very nice creek. Who knows what the streamlet was like for the millennia before a new nation's Founding Fathers decided to build a capital smack dab in the middle of it. Perhaps autumn leaves swirled in its eddies and crayfish burrowed on its rocky banks. Perhaps sun glinted off of it, glittering like scattered diamonds. Perhaps it babbled.

All we know for sure is that by the late 19th century, Tiber Creek wasn't really a creek at all. It was a sewer.

The first white settlers in the area called the rivulet Goose Creek. When a gentleman named Pope was given the grant for the land around what is now Capitol Hill in the 1660s, he changed the name to Tiber Creek. It seemed to go well with his name and the name of his estate: Rome. (Any conjecture that early patriots changed the name after 1776 as a PR move to link the new American republic with the republic of Rome, site of the original Tiber, is erroneous.)

Andrew Ellicott's 1793 "Map of the Territory" shows one fork of Tiber Creek following present-day Delaware Avenue NE. A second fork came in from the east. The two came together near what is today Union Station, flowed south to near where the Capitol would be built, then turned west to roughly follow present-day Constitution Avenue before widening broadly and emptying into the Potomac River.

As Washington grew, the Tiber was pressed into service. The Washington Canal was cut along its length from its mouth at present-day 17th Street NW to Sixth Street NW. Over time, the creek/canal became an open-topped sewer, a place to dump the detritus of city life.

"The problem was that it was at sea level and couldn't get out into the river easily," said Don Hawkins, secretary of the Historical Society of Washington, D.C. "So a dead cow thrown over the edge of the bank from the butchers at the Central Market would just kind of drift up and down for days until it got the river and went away. Not a very nice picture."

By 1871, the city had had enough of the foul Tiber. It had been a makeshift sewer. Now it became an actual sewer, covered over, bricked up. Architect Adolf Cluss supervised the construction that took the creek underground. He probably preferred being remembered as the designer of Eastern Market and the Smithsonian's Arts & Industries Building. The pipe was so big around -- more than 20 feet wide -- that a man in a boat used to go down periodically to clean it, his work illuminated by electric lights.

The Tiber Creek sewer is still in use today. It has had its share of problems. It's part of the city's combined sewer system, which means that rainwater runoff combines with sewage. When there's too much rain, the whole thing is overwhelmed and discharges into the Anacostia, Potomac and Rock Creek. A third of the city's sewers are of the combined variety, which is why the city's Water and Sewer Authority is in the process of installing new pipes.

And Answer Man wonders if the ancient river gods don't occasionally show their displeasure at the taming of the Tiber. The National Archives sits atop the old creek. During construction in the 1930s, more than 8,500 concrete piles were driven into the unstable soil to support the building's weight. Large pumps keep the foundations from flooding with creek water. Several of the other buildings along the creek's old route are occasionally threatened with water from below.

Although the Tiber is gone, you can see a monument to it at the National Museum of the American Indian. A water feature outside the museum pays homage to the vanished creek.

Send your questions about the Washington area to answerman@washpost.com.