For the State of Washington, the sales tax is a fire hose of money.

For ages, cities have wanted to poke a siphon into that hose and get a teensy bit of what's flowing inside. During the last legislative session, cities finally got that wish.

Seattle mayor Jenny Durkan is happy about the new law.

"Instead of sending this money to Olympia, we can keep it right here and put it to work," she said.

There are two ways that money could work.

First, it could build over 700 new apartments. The city builds $350,000 apartments for the bargain basement price for around $65,000 each — by leveraging other sources of funding. In some cases, other sources contribute $5 for every $1 spent by the city.

Second, the money could defray the cost of operating and maintaining the affordable housing the city’s already built.

Because it turns out, after the ribbon cutting ceremonies are over, apartment buildings still cost the city money $12,000 a year in operations and maintenance and $5,000 a year in supportive services such as counseling. Those services are especially important for the Seattleites living on the street.

Durkan hasn't said yet how the money will be divided among those two pots.