Losing our precious rainwater as creeks flow faster and muddier
As more land is converted from pastures and forests to pavement and rooftops, rain no longer soaks into the ground to percolate gradually to nearby streams and creeks. Instead, it immediately flows into storm drains and rushes into delicate creeks at high speed, washing away banks and vegetation. This causes both pollution and increased flooding in developed areas. Wells are drying up, and creek and river levels are lower than in the past because less rainwater is absorbed into the ground. Conventional developments have so much pavement that they dramatically reduce the amount of rain soaking into the ground. Instead, virtually all the rain pours into storm drains and reaches nearby creeks through stormwater systems that do not necessarily control flooding.
Pollution—it comes from us all
You might think that factories and sewage treatment plants are the big polluters, but in reality pollution comes from everywhere. Rain runs off yards, golf courses, construction sites, roads, and farms into nearby creeks and then into the Harpeth—bringing with it sediment, toxics, fertilizers, overflow from failing septic systems, and animal wastes. This is called “nonpoint source” pollution, since it doesn’t come from a single source. Nonpoint source pollution is increasing with growth and can raise the cost for water utilities to produce drinking water from the region’s rivers.
Poor streambank habitat
In a natural setting, streams have thick vegetation on both banks. Streamside vegetation helps hold streambanks in place, and also slows and filters surface water flowing into the stream. With development and landscaping, this vegetation (the riparian corridor) is often lost—either paved over or mowed down, leaving the stream with no bank-side protection. Water temperatures rise, threatening fish and other aquatic life. Nonpoint source pollution also increases and bank erosion becomes a serious threat.