Environmental Setting May 2007 species, including the bald eagle (Haliaeetus leucocephalus), wood stork (Mycteria americana), and timber/canebrake rattlesnake (Crotalus horridus) exist within the proposed DART Rail to Rowlett Corridor. The USFWS Arlington Field Office was contacted to verify known occurrences of threatened or endangered species within the proposed DART Rail to Rowlett Corridor (personal communication, June 9, 2006). According to the agency, no known occurrences of any of the listed species are documented within the proposed DART Rail to Rowlett Corridor. In addition, no threatened or endangered species were detected during the site reconnaissance. 2.7 Water Resources and Floodplains 2.7.1 Water Resources Surface Waters The DART Rail to Rowlett Corridor primarily lies within a portion of the Trinity River Basin which receives an average of 30 to 40 inches of rainfall per year (TPWD 2004). The Trinity River Basin has the largest population of any river basin in Texas. It includes parts of 34 counties and has a total drainage area of 17,969 square miles. This includes the DFW region, which encompasses more than five million people (USCB 2000). There are ten major reservoirs within the basin including Lavon Lake and Lake Ray Hubbard on the East Fork and eleven other reservoirs on the smaller tributaries, most of which are located in the DFW region (Texas Council on Environmental Quality [TCEQ] 2007). Surface water flow in the proposed DART Rail to Rowlett Corridor is generally to the east- southeast. The proposed DART Rail to Rowlett Corridor lies north-northwest of Lake Ray Hubbard. Lake Ray Hubbard, an impoundment of the East Fork of the Trinity River, and its tributaries are the major surface waters found in northeastern Dallas County. Among these tributaries are Mills Branch, Rowlett Creek, and Longbranch Creek. From west to east, the proposed DART Rail to Rowlett Alignment passes through the floodplain of Mills Branch, which parallels the proposed DART Rail to Rowlett Alignment to the south; crosses a tributary of Rowlett Creek; crosses Rowlett Creek, the largest creek in the area; crosses two additional smaller tributaries of Rowlett Creek; and crosses Longbranch Creek, just before entering downtown Rowlett. The majority of surface water runoff in the DART Rail to Rowlett Corridor would be intercepted by either storm water drains or surface waters and carried to Lake Ray Hubbard. Descriptions of the surface waters intersected by the proposed DART Rail to Rowlett Alignment are provided below. • Mills Branch Tributary: This tributary is an intermittent stream with an average Ordinary High Water Mark (OHWM) of 13 feet that is culverted under the existing rail. The stream originates just north of the existing rail and flows to the southeast, emptying into Rowlett Creek. Vegetation mainly consists of black willow (Salix nigra), hackberry (Celtis laevigata), American elm (Ulmus americana), Texas swampprivet (Forestiera angustifolia), and roughleaf dogwood (Cornus drummondii). The bottom of the channel is bedrock with no emergent or edge vegetation within the OHWM. During the time of the ____________________________________________________________________________ DART Rail to Rowlett Final Local Environmental Assessment 2-68 Environmental Setting May 2007 field survey, the channel was dry except for a small ponded area at the outfall, south of the existing rail. • Rowlett Creek Floodplain Tributary #1: This is a stream located approximately 1,300 feet west of the main branch of Rowlett Creek within its 100-year floodplain, just east of the DORBA trail. This water originates just south of SH 66 and empties into Mills Branch before connecting with Rowlett Creek. This water is perennial south of the existing rail, but exhibits intermittent characteristics upstream where it has an OHWM of 16 feet. The portion of the creek that crosses under the existing rail has an OHWM of 130 feet as the tributary is ponded at this location (0.19 acre). Four emergent wetlands associated with this water were delineated, three adjacent and one in-channel. Vegetation within these wetlands consists mainly of swamp smartweed (Polygonum hydropiperoides), balloonvine (Cardiospermum halicacabum), ragweed (Ambrosia artemisifolia), and black willow. A bottomland hardwood system surrounds these waters and contains species such as green ash (Fraxinus pennsylvanica), American elm, sugar hackberry, poison ivy and Indian woodoats (Chasmanthium latifolium). • Rowlett Creek: The creek is a perennial creek that crosses the proposed DART Rail to Rowlett Alignment approximately 0.5 miles east of Centerville Road. The creek originates in west central Collin County and flows south into Lake Ray Hubbard. The creek is characterized by steep banks with exposed roots. The OHWM of this stream as it crosses under the existing rail is 88 feet. Adjacent vegetation lies within a bottomland hardwood system and consists of pecan (Carya illinoinensis), American elm, hackberry, cottonwood (Populus sp.), poison ivy (Toxicodendron radicans), barley (Hordeum vulgare), ragweed, saw greenbrier (Smilax bona-nox), and chinaberry (Melia azedarach). • Rowlett Creek Floodplain Tributary #2: This is a stream located approximately 800 feet east of the main branch of Rowlett Creek within the 100-year floodplain. It originates just north of SH 66 and flows south into the western reach of Lake Ray Hubbard. This water is perennial south of the existing rail, which is bridged over this crossing, but exhibits intermittent characteristics upstream where it has an OHWM of 15 feet. The OHWM at the rail crossing is 112 feet where the water is ponded (0.24 acre) with a small island located near the east bank. A small (0.0003 acre), emergent wetland exists in- channel as the ponded area narrows to an intermittent stream, north of the existing rail. Around the ponded area, the banks of the water rise steeply from the water, and vegetation located above the OHWM is within a bottomland hardwood system and includes ragweed, poison ivy, annual marshelder (Iva annual), saw greenbrier, balloonvine, cedar elm (Ulmus crassifolia), and pecan. • Rowlett Creek Floodplain Tributary #3: This is a stream located approximately 630 feet west of Dexham Road within the Rowlett Creek 100-year floodplain. This water begins as an ephemeral drainage north of the existing rail and exhibits intermittent characteristics south of the rail where it flows west and connects with Rowlett Creek Floodplain Tributary #2. The tributary has an average OHWM of 9 feet and is culverted under the existing rail. Existing vegetation along the banks of this stream include ____________________________________________________________________________ DART Rail to Rowlett Final Local Environmental Assessment 2-69 Environmental Setting May 2007 ragweed, saw greenbrier, black willow, green ash, poison ivy, American elm, and sugar hackberry. • Longbranch Creek: This is an intermittent stream located at the intersection of Main Street and the existing rail with an average OHWM of 22 feet. This creek originates approximately 0.37 miles north of SH 66 and flows southeast into Lake Ray Hubbard. Within the project area, the water crosses the proposed DART Rail to Rowlett Alignment through a pipe that extends under Main Street and outfalls just south of the roadway. North of the existing rail during the field survey, the channel was dry and heavily impacted by trash and debris. Vegetation existing at this creek included roughleaf dogwood, Johnson grass, pecan, American elm, box elder, green briar and Chinese privet. Table 2-25 provides current designated use and impairment information for some of the larger water bodies near the proposed DART Rail to Rowlett Corridor, namely Muddy Creek and Lake Ray Hubbard, which are tracked by the TCEQ. Table 2-25: Summary of Surface Waters Identified by TCEQ Designated Use Impaired Water Summary Segment Domestic Parameter Segment # Aquatic Pollution Name Recreation Water Priority of Life Source* Supply Concern Public Lake Ray Contact 0820 High Water --- --- --- Hubbard Recreation Supply Bacteria levels sometimes exceed the Muddy Contact criterion 0820C High --- Low PS, NPS Creek Recreation established to assure the safety of contact recreation. Source: TCEQ, 2005 Note: *PS – Point Source; NPS – Nonpoint Source Designated uses for water bodies are defined by the TCEQ as required by the CWA. Muddy Creek (Segment 0820C), which is located approximately two miles northeast of the proposed DART Downtown Rowlett LRT Station, has been designated for contact recreation and high aquatic life use. Lake Ray Hubbard (Segment 0820), which is located approximately one mile east of the proposed DART Downtown Rowlett LRT Station, has been designated for contact recreation, high aquatic life use, and domestic water supply, as well as fish consumption. ____________________________________________________________________________ DART Rail to Rowlett Final Local Environmental Assessment 2-70 Environmental Setting May 2007 Contact recreation use is determined by measurements of three organisms including elevated fecal coliform, E. Coli (freshwater), and Enterococci (tidal water) bacteria levels. Aquatic life use designation is based on assessment of dissolved oxygen criteria, toxic substances, ambient water and sediment toxicity, and characteristics such as desired use, sensitivity of aquatic communities, and local physical, chemical, and biological characteristics. Domestic water supply use is designated for all sections used