Bacterial Survey of Lake Madeline, Galveston, Texas

Purpose/Objectives

To conduct an intensive water quality survey of Lake Madeline, located on the west end of Galveston Island to evaluate potential changes in water quality, including indicator bacteria, associated with recent installations of new sewage collection systems and in situ solar aeration systems.

The primary objectives of this study were to: 1) characterize mid-lake variations in dissolved oxygen in the Lake Madeline watershed following improvements to the sanitary sewer collection systems and installation of solar powered aeration; 2) define and delineate the surface distribution of bacteriological indicators and potential violations of state water quality criteria or screening levels in the Lake Madeline watershed following improvements to the sanitary sewer collection systems and installation of solar powered aeration; 3) identify potential ongoing sources of these bacteria within the lake's watershed; and 4) identify and evaluate the relationship of other factors including meteorological, nutrient loading and mixing and elevated bacteria levels or hypoxia events.

Study Area

Lake Madeline and Offatt's Bayou, Galveston, Texas

Project Period

2008 – 2009

Description

Due to ongoing concerns about potential risks associated with exposure to sewage contaminated water and reoccurring fish kills, the City of Galveston contracted EIH to conduct a bacteriological survey of Lake Madeline and surrounding waters during June to October 2006 (Guillen and Moore 2006). The primary objective of that study was to delineate the distribution of bacteriological indicators and potential violations of state water quality criteria or screening levels in the Lake Madeline watershed. The secondary objective was to identify the origin of these indicator bacteria within the lake's watershed.

Based on the City of Galveston's monitoring data, Lake Madeline did not appear to be meeting state of Texas contact recreation water quality standards (Guillen and Moore 2006). Various bacteriological indicators were elevated throughout the lake during periods of increased rainfall, warmer temperatures and decreased salinity. In addition to continuing bacteriological problems, Lake Madeline exhibited hypoxia in the deeper portions of the Lake. Many of these measurements were below the state minimum criteria. These low levels were reinforced by strong salinity induced stratification which reduced mixing, and apparent eutrophic (high nutrients and algae) conditions present in the upper portions of the water column. The data collected during that study and past investigations supports the hypothesis that contaminated storm water runoff is a significant source of indicator bacteria within the watershed. However, these elevated indicator bacteria probably originated from leaking wastewater collection systems (sanitary sewers). Therefore a more detailed investigation of the storm water and sanitary sewer collection systems was initiated to definitely determine the sources of contamination and remediate further discharges as needed. At that time, the City of Galveston had already embarked on a sanitary sewer rehabilitation project to address some of these issues. A follow-up monitoring study was recommended after repairs are completed and management measures implemented to document expected improvements in water quality.

Publications and Presentations

Guillen, G. 2010. Lake Madeline bacteria study final summary report. EIH Technical Report 10-014:24.

Haskett, K., Guillen, G., Moore, S., and Biggs, H. 2007. Effects of basin morphology and urban non-point source loading on Lake Madeline water quality. State of the Bay Symposium, Galveston, TX. Poster.

Guillen, G. and Moore, S. 2006. Lake Madeline bacteria study final report. EIH Technical Report 06-001:35.

Project Sponsors

• City of Galveston