Stormwater runoff is routed to inlets where it joins the city’s combined or stormwater network.  Flooding occurs when there is more runoff than the system can handle. The number of stormwater flooding events due to system capacity is used to better understand what areas are affected by overflowing stormwater pipes. Flooding reports are recorded in the city’s TrackIT system.  

The number shows flooding that has been reported in a stormwater system basin caused by insufficient conveyance capacity. The amount of reported flooding indicates a need to evaluate the local stormwater network conveyance capacity or upstream drainage pathways.  This measure does not include flooding caused by blocked inlets or flooding that occurs in areas without an existing stormwater system.

This metric is extracted from the city’s TrackIT system which records flooding reports submitted by residents.  This metric is aimed at understanding areas with insufficient stormwater network capacity.  It inherently reflects flooding in areas served by a piped stormwater network and not those served by drywells. Stormwater system performance feedback is important in understanding where existing infrastructure may need closer attention and if planned infrastructure work will be sufficient to handle predicted increases in runoff volume and peak flows. 

You can read more about how the City of Portland manages stormwater here: https://www.portland.gov/bes/stormwater