Escherichia coli (E. coli). High concentrations of bacteria in water bodies have been associated with an increased risk of becoming ill from recreational activities. In the Houston region, bacteria are the most common pollutant of concern, and an implementation plan has been drafted to address 60 bacteria-impaired segments representing 80 percent of assessed streams in the region (TCEQ, 2011). In the Houston ship channels, industrial toxins such as polychlorinated biphenyl (PCBs) and other dioxins remain a threat to aquatic wildlife and human health; consumption advisories exist for several species of fish.
The Houston region has two large river systems—the Trinity River and the San Jacinto River. These rivers are important for freshwater inflows into the Galveston Bay, with the Trinity River supplying more than half of that inflow. Ms. Gonzalez stated that with current drought conditions and rising salinity levels, many freshwater plants along the Trinity Bay Delta can no longer be found. Houston also has extensive riparian forests and bottomlands that are intricately linked to the rivers, bayous, and waterways in the region. The Trinity River bottomlands are found on the eastern side of the city, the Columbia bottomlands on the western edges of the region along the Brazos River, and riparian forests along all the bayous. These riparian zones and bottom lands provide storm water retention, flood mitigation, and water quality protection in more densely populated areas. Historically, many of these riparian zones were cleared during a period of channelization and development.
Another habitat important to the Houston region are coastal prairies, said Ms. Gonzalez; less than one percent of all native coastal prairies are estimated to be left in the United States. Early accounts from people first arriving to the Houston region described a land covered by coastal prairie with green ribbons of riparian forests along waterways. There are examples of remaining coastal prairie, including the Armand Bayou Nature Center and Katy Prairie near the University of Houston, Coastal Center. The Katy Prairie is considered conservation land and is privately held and managed for that purpose. In addition to development occurring in this habitat, invasive species such as the Chinese Tallow tree are a growing threat and require extensive resources, money, and manpower to help control. Some of the services provided by coastal prairie habitat include grazing for food production, wildlife habitat, nature viewing, and hunting.
Wetlands are another important habitat in the region, and particularly unique are Estuarine wetlands, which exist along the bay. Palustrine wetlands are freshwater wetlands that extend into the upper