Tuesday 1 October 2002

From Beth Stewart of the Cahaba River Society 

The Cahaba River is the main source of drinking water for one out of four Alabama citizens, including most of us who live in the greater Birmingham area. The river serves our families for recreation and as habitat for wildlife. The Cahaba River is the heart of Alabama’s biodiversity and imperiled freshwater and forest life. In fact, The Nature Conservancy has declared the protection of the Cahaba River’s aquatic biodiversity a national priority, naming the Cahaba one of eight “hotspots of biodiversity” that must be saved.

Drinking water and wildlife advocates for the Cahaba have common cause: managing growth in the upper Cahaba watershed. The rapid growth suburbs of the Birmingham metro area are expanding into the forested lands of the upper Cahaba watershed. These watershed lands produce the region’s raw drinking water, which is drawn from the main channel of the river. Upper Cahaba forested lands are also essential to water quality for healthy freshwater life.

Unfortunately, the river’s water quality and freshwater life are in severe decline. The cost to treat our drinking water has increased due to pollution, and we have lost 20% to 40% of fish and mussel species downstream from urban growth areas. Most of the upper and middle stretches of the Cahaba have been placed on Alabama’s official list of streams that do not meet Clean Water Act standards. The major cause is urban development, resulting in destruction of natural tributaries and stream banks and pollution such as sediment, nutrients, and toxins. The same development impacts and pollutants that are rapidly damaging the river’s significant aquatic life are also threatening the quality and cost of our region’s drinking water. 

(another, longer version)

 Overview of the Upper Cahaba River Watershed: Values and Threats

Scientists and international preservation groups such as The Nature Conservancy and the World Wildlife Fund agree that the freshwater biodiversity of southeastern rivers is globally significant. The Mobile River basin, which encompasses most of Alabama, is a vital reservoir for a rich diversity of fish, mussels, snails and other aquatic life. Yet half of all species extinctions in the U.S. since European settlement have occurred in the Mobile River basin. The great majority of these extinct species were freshwater life, lost due to damming, dredging and other river impairment. While these projects were central to the state’s economic development, we now must determine how to protect our remaining heritage of diverse river life.

The Cahaba’s significant values: The Cahaba River is the longest remaining free-flowing river in the Mobile Basin and the most significant refuge for the basin’s diverse freshwater life. The Cahaba is especially known for its many fish, mussel, and snail species. After studying over 2000 watersheds, The Nature Conservancy has named the Cahaba as one of eight river “Biodiversity Hotspots” across the U.S. worthy of special preservation efforts.

 The upper Cahaba watershed encompasses about 400 square miles from the headwaters down to Highway 52 near Helena, Alabama. This portion of the watershed holds the rapid growth suburbs of the Birmingham metro area in Jefferson, Shelby and St. Clair Counties. The Upper Cahaba Watershed is an incredible recreational and educational asset for the urban area and serves as the primary source of raw water for the Birmingham Water Works and Sewer Board, a system that serves one fourth of Alabama’s population.

Upper Watershed Threats: Suburban development is encroaching into the forested lands of the upper Cahaba watershed. These open space lands have historically produced the clean water that supports the river’s biodiversity and provides the region’s raw drinking water, which is drawn from the main channel of the river. All of the Cahaba’s values are being eroded due to urban development, which has resulted in destruction of natural tributaries and stream banks and pollution such as sediment, nutrients, and toxins.

 Biodiversity Values and Losses: University of Alabama biologists Rick Mayden and Bernie Kuhajda have described the Cahaba as "the most icthyologically diverse, free-flowing river for its size within the [North American] continent.” Of the 131 fish species historically reported from the Cahaba River, 11 are generally restricted to the upper Cahaba watershed, the project area for this grant. There are also 27 mussel and 24 snail species known to currently exist in the Cahaba watershed. Of the fifteen federally listed species in the river, the mussel species Orange-nacre mucket (Lampsilis eeroperovalis) (threatened) and Fine-line pocketbook (Lampsilis altilis) (threatened) exist in the upper Cahaba project area.

Yet the Cahaba’s heritage of biodiversity is in severe decline, mainly due to urban pollutants. Based on a study by EPA Region IV, in 1999 most of the mainstem and several major tributaries of the upper Cahaba watershed were placed on Alabama’s 303d list due to habitat degradation and declines in listed species (see Map *). The pollutants of concern are excessive sediment and nutrients. Other portions of the upper watershed are listed for toxins and pathogens related to urban development. The Geological Survey of Alabama has documented a 20 to 40 percent decline in the number of individual fish and fish species collected throughout the Cahaba River watershed over the past 20 years and a 40% decline in mussel species. The range of the Cahaba shiner (Notropis cahabae) (endangered) has declined from a 60-mile portion of the main stem to about 15 miles, with the remaining population at the greatest possible distance from the metropolitan area. Another federally listed species, the blue shiner (Cyprinella caeruleus) (threatened), was apparently extirpated from the Cahaba around 1971 when an Alabama Department of Transportation bridge project for construction of I-459 affected the only portion of the Cahaba where that species had previously been collected.

 Impacts on Drinking Water: These same pollutants are not only damaging aquatic life, but also degrading the region’s drinking water. Drinking water protection has become one of the driving environmental issues of the Birmingham region. In  2000/2001 there was a struggle over control of the Birmingham Water Board’s assets that fundamentally altered Birmingham city politics, and the region suffered one of the worst droughts in memory, resulting in severe water use restrictions.  In 2001/2002 there was an attempt to extend a massive tunnel sewer, dubbed the Cahaba Supersewer, to serve new development in the core drinking water source area. The Birmingham Water Board halted the project just short of the first of up to 14 crossings under the river due to concerns that the tunnel was too shallow and would damage the river bned and cause loss of the drinking water supply. The project was met with such fierce public opposition from both inner city and suburban citizen groups that Jefferson County terminated the current contract in September 2002, although the eventual fate of the supersewer has yet to be determined.

The level of public interest and concern about Cahaba River protection is very high in the region. This bodes well for the success of ongoing efforts to protect the river while planning for growth. The chief effort underway is the Upper Cahaba Plan, an innovative effort to merge land use planning with modeling of the water quality, water quantity, and biodiversity impacts of growth. The Cahaba River Society is among the many stakeholders guiding the planning process, which is being funded and led by the local governments. The Society also has several other programs for educating the public, building public support, improving the management of development and securing long term restoration and protection of the river.