THREATS

WATER QUALITY

The rate of population growth in the Cahaba Basin is the highest in Alabama. (Project) The subsequent urbanization of formally natural areas is rapidly altering the water quality in the Upper Cahaba Basin. Most of this growth has occurred in the last two decades in the greater Birmingham metro area. 

It is believed that the primary force shaping water quality conditions and biological communities in the Upper Cahaba Basin is this rapid urbanization and commercial development in the Jefferson, Shelby, St. Clair county area. (Project)

Multiple water quality surveys have found high levels of nitrogen and phosphorous, some heavy metals, low DO, evidence of organic enrichment, siltation and chemical spills in the upper basin.

There are at least 103 industrial discharge permits in the Cahaba Basin, releasing a variety of toxic heavy metals, chemicals and other substances. There are six municipal wastewater treatment plants in the upper basin upstream of Buck Creek with a combined discharge of 19 million gallons a day. (O’neil)

27 million gallons of treated sewage are permitted to be released from 40 sewage treatment plants each day. (Source?)

The Importance of Good Habitat

One of the greatest risks to the Cahaba comes not from the chemical alteration of water quality but the long-term and gradual alteration of physical habitat caused by modified channel structure and riparian zones, NPS sediments, and changes in natural hydrology. These changes cause some of the following problems – temperature fluctuations, sediment transport increases, DO and pH become more variable, substrate quality degrades, water depth decreases while velocity regimes become more variable. (Project)

*”Our inability to view water and associated aquatic resources as integrated, complex natural systems that provide free services to society is at the heart of this problem.” (Project)

Suburban Growth in the upper Cahaba communities of Cahaba Heights, Riverchase, Vestavia Hills, Inverness, Pelham, Hoover and Homewood. This growth has been facilitated by I-65 and I-459 construction. The lower basin provides a stark contrast to this growth. (Project)

WATER QUANTITY
Adequate water supply for both human and ecological needs is of major concern in the headwaters / Lake Purdy region of the Cahaba Basin.

IMPAIRED STREAMS / SECTIONS

The Cahaba has 111 miles of streams that either do not support or only partially support their designated uses. (EPA)

Impaired waters from 1998 303(d) list