Why does a storm overflow appear to be spilling when the map say’s it’s not?
If the map says there is no spill but you can still see water being released, it could be that the outfall is shared with a surface water system or other third party assets.
At some locations, the spill from our overflow travels through the same pipe as the cleaned water from a wastewater treatment plant, with both discharging through the same pipe. Whatever the weather, our treatment plants are working 24/7 to send cleaned water back to the environment. There may be no spill but the treatment plant will still be releasing cleaned water.
Sometimes the overflow spill shares the same discharge pipe as drainage from roads or businesses, or it could be an underground water course which drains the local area. The map may say we are not spilling but water from one of these other sources may still be seen coming from the pipe.