Extension Report

Baldwin County Extension Office

302A Byrne Street

Bay Minette, AL  36507

Telephone (251) 937-7176 or

928-0860/943-5061 ext. 2222

FAX (251) 937-7285

Beau Brodbeck

Regional Extension Agent

Forestry, Wildlife & Natural Resources

October 11, 2011

Plant a Tree This Winter for Healthy Streams

In the decades to come, water will become a highly contested resource.  It is estimated by researchers that water demand in the next 20 years will outstrip supply by an estimated 40% as a result of climate change and population growth.  While 75% of the earth’s surface is covered by water only 3% is fresh and less than .009% is located in our streams and rivers.

In Alabama, we are fortunate to have a wealth of water.  It is estimated that 18% of all surface water (rivers, creeks, and streams) flowing through the lower 48 states flows through Alabama.  This wealth of waters boosts agriculture and allows for urban and economic growth in Alabama. It is no secret that water is and will increasingly become a valuable resource for the growth and health of our communities, cities and state.

Managing and protecting this valuable resource will continue and increasingly become priority.  Water pollution is a concern in Alabama.  Common pollutants include overflowing wastewater treatment facilities (sewage), food processing industries, paper mills, municipal refuse and household garbage.  However, all the blame cannot be laid at the feet of industrial facilities, a significant amount of water pollutants are the result of runoff from our yards, streets, and parking lots.

Remember, the urban environment is an altered environment.  In our communities, towns and cities we generally convert piney, hardwood or wetland forests into concert jungles.  This is a simple fact of urbanization; we need roads, homes, commercial centers and industrial facilities to function as a society.  The consequences of this conversation from forest to concrete have far reaching implications to the health of our most valuable resource, water.

Consider the natural forest ecosystem that is dominated by forests composed of trees, shrubs, and grasses.  Now consider a rain event in this forest setting.  What happens? Rain falls on tree canopies and filters down to the forest floor composed of deep layers of leaves, branches and rotting organic materials.  Much of the rain filters into this soil and some runs-off into the small creeks.  Trees absorb some of this water for growth and the remainder charges underground aquifers or groundwater.

In comparison, consider the urban setting.  The same rain event falls on rooftops, driveways, parking lots and streets and flows into gutters and storm drains.  The storm drains, in turn, takes this water directly into creeks.

In the urban environment, very little water soaks into the soil, it is either covered by asphalt, buildings or is heavily compacted. Instead we have elevated amounts of runoff.  This runoff causes several problems to the creeks it enters. 

First, the water flowing over parking lots and streets picks up pollutants like gasoline, oil, antifreeze, and various heavy metals associated with brake and tire wear. In neighborhoods this runoff may contain lawn fertilizers (result of over fertilizing) and sediment from newly constructed homes (seen streams turn reddish brown lately).  In both cases, these pollutants are not filtered by soaking into soils, but rather end up directly in our creeks. 

Second, the channeling of runoff directly into creeks causes creeks to flood regularly.  This, in itself, causes many problems for some neighborhoods near streams. The water volumes are much higher as a result of not having trees and forest soils to capture and absorb this water.  The flooding causes erosion and streams become entrenched with collapsing banks over time.  This leads to gullies and additional sources of sediment in streams. 

Finally, during summer months the runoff coming from parking lots is heated by asphalt.  Thus, the water entering streams is hot and changes the temperature of many urban streams.  Additionally, streams without trees on banks are also warmed to unnatural temperatures by the sun (most streams in Alabama need shade to thrive).  This further degrades the water quality and can contribute to algae and other water born organisms to thrive.

All these pollutants in their various forms contribute towards unbalanced aquatic ecosystems. Over time, this results in the loss of many aquatic species and degraded water quality.  So what can we do about it?  There are two simple options that we as homeowners can implement towards cleaner and healthier streams in our neighborhoods.  The goal is to reduce surface runoff from flowing directly into creeks. 

First, plant trees.  The more trees you have in your yard, especially near stream banks or ditches, the more water they will capture. Trees capture roughly 18% of rainfall in their canopies, minimizing the water that reaches the ground.  Furthermore, roots slow water down and give it time to soak into the ground.  Studies have shown that for every 5% increase in tree cover there is a 2% decrease in surface runoff.  Be sure to plant non-invasive trees and preferable natives when possible.

Second, install rain gardens into your landscape.  Rain gardens are miniature bio-retention basins that capture runoff coming from your roof, driveway, patio or street.  Rain gardens are designed to capture water and are filled with native grasses, shrubs, and trees to slow water and allow it to soak into the soils.  Rain gardens are small beautiful water treatment plants for the runoff we generate.

Don’t forget, on the Gulf Coast we are at the bottom of every urban creek in Alabama with everyone’s pollutants.  We can’t fix what’s upstream, but we can work to protect our local streams through basic landscaping and gardening.  So plant a tree this winter for clean healthy local streams.   For information on selecting trees or on designing rain gardens, call me at 251-259-6507 or visit our website at www.aces.edu.

Email address: brodbam@auburn.edu

Phone: 937-7176 or 943-5061, ext. 2222

Baldwin County Extension Programs are supported by the Baldwin County Commission.

The Alabama Cooperative Extension System (Alabama A&M and Auburn Universities) in cooperation with the U.S. Department of Agriculture is an equal opportunity educator and employer.