With over 3.5 inches of rain we can expect a number of things.
Immediately, shellfish beds all along the coast will be closed, all of them. This is not so much because of "pollution" but because all the bacteria that is normally contained by all the water ways and storm drains will be washed out. Any salt marches are overloaded and the remainder washes out to sea.
The storm drain inhabitants (mostly raccoons and rats) will have a nice clean place to live for a while. This amount of water really gives new meaning to spring cleaning.
The beaches will be closed for 24 hours. that is how long the bacteria that we worry about is absorbed into the environment and goes down to acceptable levels.
The sewage treatment plant which also treat storm water are over loaded and large amounts (read millions of gallons) are released without full treatment (they are chlorinated and that is it).
This also means there will be sewage grease seen out in the Sound, these will float around until they wash up on shore breaking up and releasing all the bacteria they are protecting inside of them. This will close Stamford's beaches when they are seen (we look for them). The cast of plants includes Norwalk and Westchester county.
All thse nutrients that wash out are actually good in size and quality and may spur some juvinile fish growth which will bring larger fish. In a few months we may see a return of some of the missing game fish from the area.
Hey its a good start.
Info on heavy rains in 2008 it did not start till September.
2007 in March
2006 in April
Mostly it starts early - this is a late one.