Distribution and persistence of Escherichia coli and Enterococci in stream bed and bank sediments from two urban streams in Houston, TX Robin Brinkmeyer a, ⁎, Rainer M.W. Amon a , John R. Schwarz b , Tara Saxton a,1 , Dustin Roberts a,2 , Sarah Harrison a,3 , Nicholas Ellis a,4 , Jessica Fox a,5 , Katherine DiGuardi a , Mona Hochman b , Shuiwang Duan a,6 , Ron Stein c , Catherine Elliott d a Department of Marine Sciences, Texas A&M University at Galveston, Galveston, TX 77553, USA b Department of Marine Biology, Texas A&M University at Galveston, Galveston, TX 77553, USA c Total Maximum Daily Loads Program, Texas Commission on Environmental Quality, Austin, TX 78753, USA d Harris County Flood Control District, Houston, TX 77092, USA HIGHLIGHTS • Streambed and bank sediments were found to be a significant source of E. coli and enterococci bacteria to the water column. • Viable E. coli and enterococci exist as deep as 60 cm in sediments. • Sediments dominated by sand contained highest concentrations of fecal indicator bacteria. • DNA fingerprinting analysis challenged the assumption that sediment resuspension only occurs in high flow conditions. • Water quality goals may not be achievable due to an endless supply of fecal indicator bacteria from sediments. abstract article info Article history: Received 7 June 2014 Received in revised form 19 September 2014 Accepted 19 September 2014 Available online xxxx Editor: D. Barcelo Keywords: Escherichia coli Enterococci Sediment Urban stream Watershed The purpose of this research was to determine if Escherichia coli and enterococci in streambed and bank sedi- ments from two urban bayous, Buffalo Bayou and White Oak Bayou, in Houston, TX, USA are a significant source of the chronically high levels of these bacteria in the overlying water. The watersheds of the bayous lie within highly urbanized areas of Greater Houston and there is primary recreational contact with the public. Extensive sampling of the watersheds was conducted from 2008 to 2010. Both fecal indicator bacteria were found at ≥10 4 MPN g dry wt. -1 concentrations in the upper 1 cm of sediment cores with declines by orders of magnitude at 15 and 30 cm sediment horizons and in some cases 60 cm, but, nonetheless, indicating that they can remain viable even at depth. No interannual variation was observed. And, there was no correlation with percent organic matter, however there was moderate correlation (R 2 = 0.12; p = 0.001) of E. coli with sediment moisture. In sed- iments, most E. coli and enterococci in Buffalo Bayou (76%) and White Oak Bayou (87.5%) were associated with fine sand grains (60 to 250 μm). In the water column, E. coli was associated, in roughly equal percentages, with particle sizes b 10, 10–25, 25–63, and ≥63 μm (21.9, 25.6, 30.4, and 32.9%, respectively). Enterococci were mostly attached to particle sizes in the ranges of 10–25 μm (36.0%) and 25–63 μm (31.1%) as well as ≥63 μm (37.7%) (p = 0.0001). Fingerprinting of E. coli isolates from both bayous with Rep-PCR and the BOX A1R primer was used to demonstrate translocation of sediments from the upper to lower watersheds. © 2014 Elsevier B.V. All rights reserved. Science of the Total Environment 502 (2015) 650–658 ⁎ Corresponding author. Tel.: +1 409 741 7178; fax: +1 409 740 4787. E-mail addresses: brinkmer@tamug.edu (R. Brinkmeyer), tsaxton@glorienergy.com (T. Saxton), dustin.roberts@tecq.texas.gov (D. Roberts), sah288@msstate.edu (S. Harrison), nicholas.ellis@tceq.texas.gov (N. Ellis), jessica.fox@tceq.texas.gov (J. Fox), sduan@umd.edu (S. Duan). 1 Glori Energy Inc., Houston, TX 77053, USA. 2 Water Quality Division, Texas Commission on Environmental Quality, Houston, TX 77023, USA. 3 Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, MS 39762, USA. 4 Surface Water Quality Monitoring Program, Texas Commission on Environmental Quality, Houston, TX 77023, USA. 5 Air Quality Division, Texas Commission on Environmental Quality, Houston, TX 77023, USA. 6 University of Maryland, Earth System Science Interdisciplinary Center, College Park, MD 20740, USA. http://dx.doi.org/10.1016/j.scitotenv.2014.09.071 0048-9697/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv