Snohomish County PUD is offering $50 rebates for homes built when 5.0 gallon toilets were being used.
You can check your water bill and see if you qualify,

Snohomish County PUD originally began its operations as a water utility in 1946 (adding electric service in 1949) with the construction of the Lake Stevens Water System. Now, the PUDís Water Resources Division serves over 16,000 customers in Lake Stevens, Granite Falls area, Dubuque, Sunday Lake, Skylite Tracts, Pilchuck 10, Lake Roesiger, and May Creek. Most of our customers are supplied with water purchased from the City of Everett, and some customers are supplied by well water.