Trickle down economics

Perhaps, after reading the Northfield News on Wednesday, you think the City Council has agreed to some new stormwater fee with which to punish businesses who want to expand.  No, the Council is making decisions to address the trickle down economics of stormwater management.

Stormwater is regulated at the federal level through the Clean Water Act.  The MPCA administers CWA programs and any additional Minnesota stormwater regulations.  Northfield has what’s called a designated MS4 permit. This permit requires, since we can’t stop storms, that Northfield develop a SWPPP (that’s a stormwater pollution prevention program) that incorporates BMPs (best management practices) to manage the water once it hits the ground (or the roof).  To complexify matters, the Cannon River is Outstanding Resource Value Water which requires specific (additional) BMPs mostly concerning construction and in a buffer zone near the river – check out the cool impaired waters map.

The basic principle is to reduce runoff reaching the river by infiltrating water on-site.  Impervious surfaces whether natural (bedrock) or manmade (pavement, roofs, buildings) don’t allow infiltration, so the City must find ways to divert that runoff to regional ponds, nearby swales or raingardens.  Here’s how we do it

• All property pays a monthly stormwater utility fee to pay for the construction and maintenance of stormwater infrastructure
• Anyone – commercial or residential – who applies for a building permit (for a project which has stormwater implications), plat, or site plan review must submit a stormwater management plan.  The SWAC (stormwater access charge) approved Tuesday is for those properties where no management is possible on-site – like those in the completely built up downtown – and so we have established a fee in lieu of on-site infiltration which is analogous to the better known SAC/WAC (sewer and water access charges, respectively) as a buy-in to the stormwater system.  We must, to reduce stormwater runoff under the MS4 and pay for the city’s system, charge a fee something like this.  We can argue about whether the theoretical raingarden calculation model is the right one, we can consider whether it is a useful economic development tool to subsidize this fee to encourage development, and we can think about whether there are other incentives and tools (how much green roof would one need, for example, to reduce the stormwater sufficiently or what if a property owner made all pavement pervious?  What about rain water harvesting?).
• Construction projects have additional regulations about managing runoff, sediment and erosion.