There are flood advisories brewing for the snow melt that will be caused by the coming rain.  See the weather advisories at the UofW Weather page for the most recent reports from the U.S. Weather Service.

The last time a weather situation like this occurred in Bellingham was in January 2009, and the City of Bellingham Public Works Department was asleep at the switch.  Basements flooded all over town with sewage backing up through drains.  All homeowners insurance coverage has specific exclusion clauses against sewer backups, and the city hid their negligent incompetence behind sovereign immunity.  The result was that over a dozen homeowners had to eat thousands of dollars of damages.
 
What happens is,  the snow acts like a sponge.  The heavy rainfall saturates the sponge-like snow.  When the snow finally melts, several hours of rainfall is released in very short period of time.  This creates storm flows at levels usually only seen in extraordinarily heavy rainfalls.
 
In many places, the city storm sewers are above the sanitary sewers, and when the storm sewers are overloaded, the excess water gets channeled into the sanitary sewers.  The high flow rates increase the water pressure in the sanitary sewers so the raw sewage surges out of basement floor drains, showers, sinks, and toilets.
 
The city has diversion valves that will vent the excess raw sewage into Bellingham Bay.  In 2009, they delayed for approximately six hours before dumping the excess by opening the valves.  The result of this pointless delay was that many citizens stored tens of thousands of gallons of the city’s raw sewage at great personal expense and damage.
 
My own investigations found that basements in the York and Alderwood neighborhoods were flooded last time.  Because of the silence by the city and the lack of professional reporting by the newspaper, the full extent of the sewage flooding in 2009 was never ascertained.
 
Cliff Mass’ weather blog is here.