Water and Sediment Quality
For the most part Galveston Bay has been able to maintain good water quality because it is shallow, well-mixed, and well-aerated. The vast majority of water quality problems are concentrated in the western, urban tributaries of the bay where municipal and industrial development is most pronounced.
The metropolis of Houston and its associated suburban communities occupy the western side of the bay, while the eastern side remains largely agricultural and undeveloped. Urban and suburban development is very significant to the bay through the contribution of polluted stormwater runoff from parking lots, streets, highways, roofs, and yards (Newell et al. 1992; Basnyat et al. 1999; Wu et al. 2008). Agriculture on the eastern shore contributes nonpoint sources of herbicides and pesticides. Livestock operations can serve as sources of bacteria. Nutrients may come from a variety of sources, including agriculture, suburban development, and atmospheric deposition.
Water quality parameters of concern are fecal coliform bacteria, pH, and dissolved oxygen. The declining trend in concentrations of chlorophyll a noted in the last edition of State of the Bay appears to have leveled out in recent years. Fecal-coliform concentrations in Galveston Bay tributaries are of concern. They have shown a decline in measured concentration but, unlike many of the water quality measures, they continue to exceed water quality criteria. Recent data suggest declines in pH and dissolved oxygen concentrations in some areas of the bay. The reasons for the declines are unknown at this time.
Sediment quality is improving overall. Cadmium, chromium, copper, and lead concentrations have declined in sediments of the Upper Houston Ship Channel. Some metals, such as mercury, still exhibit spikes in concentration in this area in some years. Sampling of sediment contamination is temporally and spatially sparse, making careful assessment of progress difficult. Monitoring of water and sediment contamination by assaying the concentration in tissues of organisms shows elevated concentrations of PCBs and some spikes in mercury concentrations.
Basnyat, P., L. D. Teeter, K. M. Flynn, and B. G. Lockaby. 1999. "Relationships between landscape characteristics and nonpoint source pollution inputs to coastal estuaries." Environmental Management no. 23 (4):539-549.
Newell, C.J., H.S. Rifai, and P.B. Bedient. 1992. Characterization of nonpoint sources and loadings to Galveston Bay. In Galveston Bay National Estuary Program Publication GBNEP-15. Webster, Texas.
TCEQ. 2008b. Texas 303(d) List. Texas Commission on Environmental Quality 2008b. Available from http://www.tceq.texas.gov/assets/public/compliance/monops/water/08twqi/2008_303d.pdf.
Wu, C. J., L. L. S. Lin, R. Bajpai, and D. D. Gang. 2008. "Nonpoint Source Pollution." Water Environment Research no. 80 (10):1827-1843.