It is based on the estimated amount of stormwater runoff that is contributed by each type of use.
Single-family properties are assessed slightly more than vacant land because more water runs off hardscapes and roof tops than soil and vegetation when it rains.
Similarly, commercial properties, which typically have extensive paved areas, pay more than single-family residential properties.
The amount assessed through the 1984-originated benefit assessment does not increase with inflation. In 1984 the $9 assessment for less than ¼ acre single family parcels had the same buying power as $21.47 in December 2018.
| Parcel type | 0 to .25 acre | .25 to 1 acre | 1 to 10 acres | 10 to 100 acres | 100 to 1000 acres |
| Farm, Ag & Unimproved |
$8 | $12 | $20 | $36 | $42 |
| Single Family | $9 | $13 | $21 | $37 | $37 |
| Multi-Family | $20 | $47 | $123 | $200 | $200 |
| Commercial & Industrial |
$28 | $118 | $244 | $522 | $522 |