Habitat has been degraded by alteration of stream banks and bottoms; channelization; inadequate storm water management; inappropriate placement of culverts, pipes, and bridges; road maintenance; and haphazard silvicultural and agricultural practices (USFWS 2011). The persistence of a constant flow of clean groundwater from various springs has somewhat offset the destruction of the species' habitat, water quality, and water quantity (USFWS 2011). Range has been reduced by habitat destruction, and dispersal barriers (e.g., pipes and culverts for road crossings; channelized stream segments; and areas subject to emergent aquatic plant control) contribute to the separation and isolation of Rush Darter populations, which now experience increased likelihood of local extirpation (USFWS 2011).
The Rush Darter is vulnerable to non-point source pollution, urbanization, and changes in stream geomorphology due to its localized distribution in parts of two unconnected stream drainages and its apparent low population sizes. Non-point source pollution from land surface runoff can originate from virtually any land use activity and may include sediments, fertilizers, herbicides, pesticides, animal wastes, septic tank and grey water leakage, and petroleum products. These pollutants tend to increase concentrations of nutrients and toxins in the water and alter the chemistry of affected streams such that the habitat and food sources for species like the Rush Darter are negatively impacted. Construction and road maintenance activities associated with urban development typically involve earth moving activities that increase sediment loads into nearby streams, and other siltation sources, including timber harvesting, clearing of riparian vegetation, and mining and agricultural practices, allow exposed earth to enter streams during or after precipitation events. The Rush Darter's range is in close proximity to metropolitan Birmingham, Alabama, an area in which all of these activities are occurring, so impacts from these activities to the rush darter and its habitat are very likely to occur. Land use practices that affect sediment and water discharges into a stream can also change the erosion or sedimentation pattern of the stream, which can lead to the destruction or modification of in-stream habitat and riparian vegetation, stream bank collapse, and increased water turbidity and temperature. Excessive siltation can make the habitat of Rush Darters and associated benthic fish species unsuitable for feeding and reproduction by covering and eliminating available food sources and nest sites. Sediment has been shown to wear away and/or suffocate periphyton (organisms that live attached to objects underwater and provide likely food items for species such as the Rush Darter), disrupt aquatic insect communities, and negatively impact fish growth, physiology, behaviour, reproduction and survivability (Waters 1995, Knight and Welch 2001). Sediment is the most abundant pollutant in the Mobile River Basin (Alabama Department of Environmental Management 1996). [From USFWS 2002]
Within the Clear Creek drainage, Johnston and Kleiner (2001) reported that during August 2001, land uses in the Doe Branch and Mill Creek area appeared to be dominated by forests and that there were no obvious threats to water quality. However, U.S. Fish and Wildlife Service and U.S. Forest Service (USFS) personnel noted extensive siltation at the bridge over Doe Branch at County Road 329 on March 12, 2001, during a modest spring rain and also noted siltation at several other road crossings and at other tributaries in the immediate area. Johnston and Kleiner (2001) reported that recent clear cutting in the Wildcat Branch watershed may have increased sedimentation into the stream. Approximately 84 percent (i.e., 5 km or 3 miles) of Wildcat Branch is privately owned, and recent land exchanges within the Bankhead National Forest have taken about 0.9 km (0.6 miles) of stream west of Clear Creek out of USFS management and protection. Therefore, it is likely that additional, periodic sedimentation events will occur in the Clear Creek drainage that may impact Rush Darter populations and habitat. Cove Spring is a water source for the West Etowah County Water Authority. Water that is pumped from the spring for human consumption is chlorinated on the site, and an overflow pipe from the building that protects the spring outfall provides a constant water source for the spring run. Service personnel visually evaluated the habitat within Cove Spring and its spring run and found that it appeared suitable for Rush Darters. However, it is not known if previous releases of chlorinated spring water from the overflow pipe might have contributed to the apparent loss of the species at this site. Additional investigation is needed to confirm that chlorination caused the demise of the darters at this site. [from USFWS 2002]
Blanco (2001) identified siltation from development projects as the greatest threat to the fauna of Turkey Creek. Blanchard et al. (1998) identified five specific non-point source siltation sites that have impacted the Turkey Creek watershed, including four sites affecting Beaver Creek, which is a major tributary to Turkey Creek. These sites included bridge, road, and sewer line construction sites and a wood pallet plant. In addition, Service personnel noted in 1998 that Turkey Creek at the confluence of Tapawingo and Penny Springs was sediment-laden and completely turbid after medium to heavy rainfalls. Four major soil types occur within the Turkey Creek watershed and all are considered highly erodible due to the steep topography (R. Goode, Natural Resources Conservation Service, Birmingham, Alabama, pers. comm. 1998). Therefore, any activity that removes native vegetation on these soils can be expected to lead to increased sediment loads in Turkey Creek, and urbanization, in particular, has contributed significantly to siltation within the Turkey Creek watershed (U.S. Fish and Wildlife Service 2001), including the areas near Penny and Tapawingo Springs. Industrialization is extensive throughout the watershed, particularly near the type locality for the rush darter (Bart and Taylor 1999). [from USFWS 2002]
Interspecific competition between the Watercress Darter and the Rush Darter at Penny Springs needs study to determine if the robust Watercress Darter population is negatively affecting the Rush Darter, as has been suggested by Stiles (Samford University, pers. comm. 2001). [From USFWS 2002]