What is Stormwater?
Stormwater is water on land surfaces that originates from precipitation. It is a natural and important part of the hydrologic cycle. Some precipitation soaks into the ground and becomes part of the soil moisture. Most of it runs over land and arroyos or through streets, channels and drains.
A watershed is a land surface that produces stormwater runoff during precipitation. The flow accelerates as it drops in elevation, and increasing amounts of debris are carried by the stream. A large amount of precipitation in a small watershed produces a destructive stream of stormwater runoff. The combination of speed plus debris increases the destructive force of the flows.
Flooding occurs when stormwater runoff exceeds the capacity of an arroyo or channel. Adverse impacts include dislocation, property damage and loss of life. Damage from runoff can be curtailed by implementing the following:
- land use development controls and open space planning.
- erosion controls that limit the amount of rocks and debris washed away with the runoff.
- structural flood control systems, and
- stormwater systems.
A stormwater system is designed to minimize flooding. It collects stormwater runoff, dissipates energy (reduces speed of flowing water), removes debris, and safely channels the flow to a designated collection point or receiving stream. El Paso's stormwater system includes man-made and natural features.
Arroyos and Open Space
Natural arroyos provide a stormwater runoff conveyance with built in energy dissipation and debris removal features. Some arroyos are protected from development and remain as natural channels. Natural depressions can also be used to retain stormwater runoff. These areas can be integrated into the stormwater system while being preserved as wilderness areas.
Detention ponds are a key part of the stormwater system. They retain water, dissipate energy, percolate stormwater into aquifers and remove debris. Historically, ponds were narrow, deep and fenced to keep people out. Recently, they have been made wide and shallow, so grass, trees and other park features can be incorporated. More detention ponds will be constructed as park ponds. This allows them to retain their stormwater function and increases the number of city parks.
Maintenance is a critical component of a successful stormwater system. Each component is cataloged in a computerized maintenance management system that proactively generates work orders. Regularly scheduled maintenance ensures that personnel and equipment are used efficiently, and facilities are kept in working order.
A master plan is the second critical component of a successful stormwater system. El Paso's master plan divides the city and some areas outside the city into drainage basins. Each basin was analyzed, and projects were recommended to improve the system's efficiency. The projects are incorporated into the capital improvement program.