In cooperation with the Houston-Galveston Area Council
By Jeffery W. East
U.S. Geological Survey
Open-File Report 02–082
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Contents
Abstract
Introduction
Purpose and Scope
Description of Christmas Bay System
Data Collection
Acknowledgments
Hydrologic Data
Water-Quality Data
Continuous Water-Quality Properties
Monthly Water-Quality Properties and Constituents
Periodic Water-Quality Properties and Constituents
Sediment-Quality Data
Summary
References Cited
Figures
| 1. | Map showing Christmas Bay system and locations of data-collection stations |
| 2. | Map showing locations of data-collection stations outside Christmas Bay system |
| 3. | Boxplots showing distribution of gage height at Christmas Bay and tidal altitude at the Galveston Pleasure Pier, February 1999–February 2000 |
| 4. | Graph showing rainfall at National Weather Service gage, Scholes Airfield, Galveston, February 1999–February 2000 |
| 5. | Diagram showing wind speed and direction at Christmas Bay and Freeport, February 1999–February 2000 |
| 6. | Boxplots showing distribution of (a) specific conductance, (b) pH, (c) water temperature, and (d) dissolved oxygen in Christmas Bay, February 1999–January 2000 |
Tables
| 1. | Summary of data-collection activities in the Christmas Bay system, February 1999–March 2000 |
| 2. | Maximum, minimum, and mean gage heights in Christmas Bay, February 1999–February 2000 |
| 3. | Maximum, minimum, and mean specific conductance, pH, water temperature, and dissolved oxygen in Christmas Bay, February 1999–February 2000 |
| 4. | Monthly and periodic water-quality data in Christmas, Bastrop, and Drum Bays, February 1999–January 2000 |
| 5. | Semivolatile organic compounds in samples collected using a semipermeable membrane device deployed in Christmas Bay, February 29–March 29, 2000 |
| 6. | Grain size in bed-sediment samples collected in Christmas, Bastrop, and Drum Bays, November 30, 1999 |
| 7. | Carbon and major and trace elements in bed-sediment samples collected in Christmas, Bastrop, and Drum Bays, November 30, 1999 |
| 8. | Semivolatile organic compounds (mostly polycyclic aromatic hydrocarbons) in bed-sediment samples collected in Christmas, Bastrop, and Drum Bays, November 30, 1999 |
| 9. | Organochlorine pesticides in bed-sediment samples collected in Christmas, Bastrop, and Drum Bays, November 30, 1999 |
The Christmas Bay system is a group of three small secondary bays (Christmas, Bastrop, and Drum Bays) at the southwestern end of the Galveston Bay estuarine system in Brazoria County, Texas. During February 1999-March 2000, hydrologic, water-quality, and sediment-quality data were collected from each of the three bays to establish baseline conditions. Gage-height fluctuations closely matched open-water tidal fluctuations. Rainfall during February 1999-February 2000 was about 20 percent below the annual average. Specific conductance, pH, water temperature, and dissolved oxygen monitored at 30-minute intervals in Christmas Bay for 13 months showed seasonal variations typical of monitoring stations on the Texas Gulf Coast. Prevailing winds were from the southeast. Monthly water-quality sampling for 13 months showed that in each of the three bays concentrations of major ions were small, and most nutrient concentrations were at or less than minimum reporting levels; indicator bacteria counts were consistently higher in samples collected from Drum Bay. Several trace elements (sampled twice) were detected in small concentrations. The only organochlorine pesticides (sampled once) that were greater than minimum reporting levels were atrazine, deethylatrazine, metolachlor, and simazine. During February 29-March 29, 2000, three semipermeable membrane devices were deployed at the Christmas Bay monitoring station. Seven of 77 semivolatile organic compounds analyzed in the lipids from the devices were detected in minute amounts. Analyses of surficial bed sediment sampled once in each of the three bays yielded detections of a number of semivolatile organic compounds; all concentrations were less than 10 micrograms per liter and much less than the respective benchmark concentration for those compounds that have had a benchmark concentration established for the protection of aquatic life.