Protecting Tres Palacios Bay Tres Palacios Bay is an eco- TEXAS COMMISSION ON ENVIRONMENTAL QUALITY logically important part of the Matagorda Bay system and
the Texas Gulf Coast. The area Prices Slough and Tres Palacios Bay around the bay is home to many kinds of plants and animals, and includes freshwater and saltwa- ter marshes, estuaries, and open bay. The coastal marshes and estuaries of Tres Palacios Bay serve as nurseries for a large number of coastal aquatic spe- cies, including many types of commercial fish, shrimp, crabs, to the local economy that they are the major food pro- duced in Matagorda County, exceeding both rice and and oysters. Tres Palacios Bay cattle. Consequently, the Port of Palacios has adopted itself is among the most produc- the title “Shrimp Capital of Texas.” tive coastal areas of the state. Water Quality in Tres Palacios Bay The quality of water in Tres Palacios Bay is an impor- A Valuable Natural Resource tant component of the bay’s ecosystem and plays a Tres Palacios Bay, along with the entire Matagorda vital role in the productivity of the entire Matagorda Bay system, is an important commercial and rec- Bay coastal area. Water quality testing conducted by reational fishing resource. In 2004, the value of all the TCEQ prior to 2004 showed that, in several of the commercially caught finfish, shrimp, oysters, and bays in the Matagorda Bay system, concentrations of crabs within the Matagorda Bay system exceeded $3.3 dissolved oxygen were sometimes outside the range million, according to the Texas Parks and Wildlife De- required to support a healthy aquatic community. The partment. Additionally, anglers from across the state bay systems identified as having low dissolved oxy- and nation come to the area to catch speckled trout, gen were Matagorda Bay–Powderhorn Lake (Segment redfish, flounder, and many other types of fish. These 2451), Tres Palacios–Turtle Bay (Segment 2452), and anglers often rent lodging in the area, rent or buy Carancahua Bay (Segment 2456). boats and equipment, and eat at local restaurants. Oxygen, which dissolves in water, is essential for The Port of Palacios is one of the busiest fishing ports the survival of aquatic life. The amount of dissolved in the country. In 2004, fishing operations brought oxygen in water fluctuates naturally, but various ashore and processed $27.6 million worth of seafood human activities can cause unusually low dissolved- caught in area bays and the Gulf of Mexico. Shrimp is oxygen conditions that may harm fish and other the port’s main catch. In fact, shrimp are so valuable aquatic organisms. The State of Texas requires that The Port of Palacios
water quality in these coastal water bodies support According to data collected between 2004 and 2006 the exceptional aquatic life that normally thrives in by the University of Texas Marine Science Institute, them. In response to the water quality conditions in two areas of Tres Palacios Bay showed persistently low the Matagorda Bay area, the TCEQ began a project to dissolved oxygen—an area near the city of Palacios determine the extent, severity, and possible causes of (Station 14689) and Palacios Harbor (Stations 13382 the low dissolved oxygen. and 18867). Location of Monitoring Stations for the Project
Segment Stations 2452 13382, 13381, Tres Palacios– 14682, 14689, Turtle Bay 18867 2451 17354, 13377, Matagorda Bay– 13378 Powderhorn Lake 2456 13388 Carancahua Bay
Credit: Figures courtesy of the University of Texas Marine Science Institute.
2 Lowest Dissolved Oxygen surface current can add significant quantities of oxy- Concentrations Recorded Over gen to a body of water. This process is called aeration. a 24-Hour Period in Tres Palacios Bay, Segment 2452 Aquatic plants also add oxygen to the water. During 10 the day, plants use nutrients, water, and sunlight to 13381 13382 produce their own food. This process is called pho- 14682 14682 tosynthesis and produces oxygen as a by-product. 8 18867 Min DO Standard Photosynthesis by floating algae is a common source of dissolved oxygen in the bay. 6 In addition, oxygen dissolves better in water at low
4 temperatures. Cool, rapidly flowing waters often
Dissolved Oxygen (mg/L) Dissolved Oxygen Mixes and Circulates 2
0 Aeration O2 O2
4/6/20055/3/20056/2/20057/1/20058/2/20059/6/20059/6/2005 6/6/2006 6/15/20047/16/20048/18/20049/14/2004 10/4/2005 7/11/20068/15/20069/12/2006 10/12/2004 10/10/2006 Sample Date Photosynthesis The minimum level of dissolved oxygen required to sup- port the aquatic life use of the bay is 3 milligrams per liter O2 (mg/L). In Palacios Harbor (Stations 13382 and 18867), 6 of 23 measurements—26 percent of the total—were below the minimum level required. Dissolved O2 What Is Causing the Low Oxygen Levels? There are several possible causes of low dissolved oxygen in Palacios Harbor and Tres Palacios Bay. Dissolved Oxygen Is Depleted Among these are:
● Aeration Oxygen-consuming pollutants in rainfall runoff O O that can wash into the harbor during storms. 2 2 Photosynthesis ● Onboard trash or organic wastes such as fish by-catch and shrimp heads thrown directly into the water. O2
● The physical shape of the port itself, which keeps O2 O2 wave action low and makes it difficult for tides to flush and renew harbor waters.
The balance between dissolved oxygen and organic Respiration matter affects the overall level of dissolved oxygen in the bay. ������������������������������������������Dissolved oxygen is increased by processes LEGEND called aeration and photosynthesis. It is decreased by O2 Oxygen bacteria that feed on organic waste like dead fish, fish Organic Waste (shrimp heads, by-catch, etc.) parts, or shrimp heads. Healthy Aquatic Organisms
Dissolved Oxygen Dead Aquatic Organisms The oxygen in the air we breathe dissolves into water Bacteria through natural processes. Waves or even a strong 3 contain significantly more oxygen than warm, slow Getting Involved in the Solution moving ones. Warm, stagnant water bodies that are Tres Palacios Bay is a valuable natural resource worthy sheltered from the wind—such as marinas and boat of the highest level of environmental protection. The harbors like Palacios Harbor—tend to have lower lev- State of Texas is obligated under federal law to preserve els of dissolved oxygen. and protect Tres Palacios Bay. However, comprehensive resource protection can only be accomplished through the care and the commitment of local stakeholders and the public.
Aerial view of The State of Texas regulates discharges Palacios Harbor of wastewater and some storm water into waters of the state, including Tres Palacios Bay, through the Texas Pollutant Discharge Elimination System. The state also enforces laws against unauthorized releases of pol- lutants into its waters through various other programs. However, while environmental regulation can help protect Tres Palacios Bay, ultimately the well-being of the bay ecosys- tem is directly dependent on the stewardship Credit: Photograph copyrighted by Pro-Aire Aerial Photography,
For More Information To find out more about water quality in the Tres Palacios area, call the TCEQs Total Maximum Daily Load Program at 512-239-4900 or send an e-mail to
GI-363 2/07 Texas Commission on Environmental Quality
The TCEQ is an equal opportunity/affirmative action employer. The agency does not allow discrimination on the basis of race, color, religion, national origin, sex, disability, age, sexual orientation or veteran status. In compliance with the Americans with Disabilities Act, this document may be requested in alternate formats by contacting the TCEQ at 512-239-0028, Fax 512-239-4488, or 1-800-RELAY-TX (TDD), or by writing P.O. Box 13087, Austin, TX 78711-3087.
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