How are impervious surfaces a pressure on the Bay?
Impervious surfaces that replace natural, vegetated areas do not allow precipitation to soak into the soil. Instead, water runs off the hardened surfaces and into sewers, local rivers, streams and the Bay. • As water runs across impervious surfaces, it picks up pollutants like nitrogen, phosphorus and chemical contaminants that can harm aquatic life. • Impervious surfaces increase the amount and speed of runoff flowing into storm drains and local streams, which can alter natural stream flows. Fast-moving runoff can also erode stream banks and beds, sending more water-clouding sediment into streams, rivers and the Bay. • Stormwater that is diverted into storm drains usually bypasses wetlands and riparian forest buffers that naturally slow and filter runoff. • Increased runoff from impervious areas can also cause flooding. • Hardening surfaces limits the amount of rain that is able to seep into the soil and replenish groundwater supplies, which are an important source of drinking water i
