Divert your rainwater, lower your utility bill

City finalizes new 'stormwater' credit

The city will retool your utility bill next year, changing the way it charges for sewers and adding a new "stormwater" credit.

The new utility bills will have separate lines for storm sewer and sanitary sewer.

The credit gives property owners a break if they have rain gardens, green roofs, retention ponds or other improvements that reduce rainwater runoff, or improve runoff water quality.

The City Council approved a three-tiered credit system 11-0 Nov. 5.

What changed?

The city currently charges property owners for sewer services based on water use, assuming the more water a property uses, the more it adds to sewer demand. However, that system does not account for stormwater runoff. For instance, surface parking lots get no sewer bill because they use no water, yet they generate considerable runoff.

Councilmember Sandy Colvin Roy (12th Ward) said basing some sewer fees on runoff estimates meant 2,300 properties that never paid sewer bills before now would pay them next year.

The change would have minimal impact on many homeowners, she said. The intent was not to raise more money, but to create fairer bills.

Public Works is estimating changes to individual properties, and utility payers will get a letter explaining them, said John McLain who is overseeing the project.

Stormwater credit applications will be available before the city changes the billing system early next year. The new credit system allows property owners to apply for "quality" and "quantity" reduction credits.

If property owners divert runoff from roofs and driveway slabs into rain gardens or filter strips, or use other approved practices to improve water quality, they get a maximum 50 percent credit. If the property treats 100 percent of the runoff, it gets the maximum credit. If the rain garden handles 50 percent of the runoff, then the credit drops proportionally, to 25 percent.

The city estimates the stormwater fee for a single-family detached home at between $8 and $9 a month. Than means the maximum 50 percent credit would save slightly more than $4 a month or about $50 a year.

"It is probably not enough for homeowners to be driven to do this for monetary reasons," Colvin Roy said. "We are hoping it will encourage people,

like the recycling credit drives people to recycle."

The plan requires some basic information from applicants, such as the location of the filter strip or rain garden and its dimensions. The property owner has to sign a statement certifying the information is correct.

Property owners get a second "quantity" credit (maximum 50 percent, plus the first credit) if they create retention/detention ponds or other improvements to handle a 10-year rain event on-site. (A 10-year rain drops 2.2 inches in one hour or 4.2 inches in 24 hours.)

To qualify, property owners need a landscape architect or professional engineer to sign off on some calculations, or they must provide documents from a product manufacturer.

The third credit applies to larger properties that create ponds and other improvements to handle a 100-year rain, which qualify for a 100 percent credit.

If all goes according to plan, the new system goes into effect on January's first utility bill, McLain said. He did not yet know how the new credit system might affect the bills of people who don't get the credits.

Other cities that offered credits had few takers, McLain said. But the new Minneapolis system is unique and created a greater incentive. City property owners also tend to be more environmentally conscious.

"Knowing for sure how many people will apply is pretty much a guess right now," he said. If "there are bunches of people coming in and getting these large credits, then we will have to reevaluate the credit rules."