8th Ave Carroll fire hydrant flood

Periodically the DEP (who is responsible for all public water) has to flush the hydrants. It seems like sometimes they run one for a long time or a whole bunch for a shorter period. From the interwebs:
It serves the following purposes:

* Flushes sediments from mainline pipes (which enhances water quality)
* Verifies the proper operation of fire hydrants and valves
* Helps find weaknesses in the water system
* Checks for closed valves and weak flows in the water mains
* Verifies ample flow for fire fighting

Flushing the water system on a routine basis removes sediment from lines and keeps the entire distribution system refreshed.
Each water main over 12 inches in diameter and every fire hydrant is flushed on an annual basis. Water mains of less than 12 inches in diameter are cleaned every three years.
As a result of the flushing procedure, residents in the immediate vicinity of the work may experience temporary discoloration of their water. This discoloration consists primarily of harmless silt and precipitates and does not affect the safety of the water. If you experience discoloration in your water after crews have been flushing in your neighborhood, clear the pipes in your own home by running all water faucets for a minute or two.
This same philosophy of water line preventive maintenance is one that you should use in your own home. Your home's water heater should be drained and flushed at least once a year to keep it working efficiently and to protect the quality of water inside your home. Also, if you go out of town and there is no water use in your home for a week or more, when you return it's always a good idea to run all your faucets for a minute or so before using the water. This ensures that you don't use any stagnant water that may have developed in your home's pipes while you were away.