As of November 1st, Mercer Island's new Residential Code is in effect. While there has been a lot of focus on what these codes mean to residents, another code that homeowners and developers may not be aware of (but is something that should be emphasized even more) is the Updated Stormwater Management Standards. 

These updated standards come directions from the Federal Clean Water Act and Washington's Department of Ecology, requiring cities to comply with the National Pollutant Discharge Elimination System (NPDES) for stormwater control standards. Mercer Island is behind on adopting these standards, but as of this past July, the new standards have been approved and are now in effect.

What this means for Mercer Island residents is that the city will be holding them accountable for having better storm management systems in place at their home, and these standard will affect building new structures as well. Homes must now use a system of Low Impact Development (LID) to ensure that stormwater is being drained in a way that does not cause polluted water runoff. This essentially comes down to needing a certain amount of land for water to slowly flow into the ground (otherwise known as bioretentive land or surfaces, like rain gardens), compared to the square feet of impervious, hard surfaces on a property.