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Monday, March 24, 2014

Oil Spills - A Continual Risk for Galveston Bay Habitats

Galveston Bay Oil Spill

An environmental overview of Galveston Bay oil spill
The above image was created from https://gis1.harcresearch.org/oilspill/.

**As soon as more information emerges, it will be posted.** Last Updated 03/26/2014 10:55 AM CST

The potential for oil spills is ever-present in Galveston Bay. Oil spills and contamination are an environmental risk and trade-off that we live with as our local economy benefits from shipping and industrial activities. Petroleum compounds from a spill can be degraded by microbes present in the environment, but may remain at harmful concentrations for months to years before being completely degraded.

HARC has created an interactive mapping application to allow the public to understand some of the potential environmental impacts the March 2014 oil spill may have on the Galveston Bay. To view this application, please visit https://gis1.harcresearch.org/oilspill/.

Oil spills impact the Galveston Bay ecosystem at multiple levels. Petroleum is highly toxic to estuarine organisms, particularly larval stages. When spilled in water, the lightest and most volatile components evaporate and become air pollution. Heavier components may float and combine into tar balls that wash upon the shore inundating shoreline habitats, including marshes and beaches. The heaviest components sink to the sediment where they can damage benthic organisms, such as oysters.




Of particular concern for the ―now estimated 168,000 gallon― oil spill near the Texas City Dike on March 22, 2014 are the bay’s oyster reefs. Galveston Bay oysters are an important commercial fishery and oyster reefs are a key coastal habitat. The oyster reefs in Galveston Bay are currently stressed because of the storm surge impacts of Hurricane Ike in 2008 and the lack of freshwater inflows to the bay during the 2011-2012 drought. Additionally, the commercial oyster harvest is currently closed due to a Dynophysis harmful algal bloom. Oyster reef restoration efforts are underway in the bay, but it will take some years for this habitat to recover from the multitude of natural and man-made impacts over the last 6 years. It is still too early to calculate the detrimental effects of this oil spill on existing reefs and current restoration efforts.

Also of great concern are the nearby colonial nesting waterbird habitats. The Bolivar Flats Shorebird Sanctuary and the Horseshoe Marsh Bird Sanctuary lie directly southeast of the spill site. Houston Audubon has observed approximately 100 birds with varying degrees of oil. The Pelican Island and Little Pelican bird rookeries (nesting colony locations) are situated immediately southwest of the spill. March is still winter nesting season for species of colonial water birds that call Galveston Bay home this time year. Human-caused disturbance of nesting habitat in the bay contributes to the decline of some bird species such as tri-colored heron, white-faced ibis, reddish egret, and others (Lester and Gonzalez, 2011).

The Texas General Land Office (GLO) Oil Spill Prevention and Response Program works with the U.S. Coast Guard and responsible parties to end, contain, and clean up oil spills in waters of the Texas Coastal Zone. The GLO also collects data describing the number, volume, and nature of oil spills in Texas bays. Data for Galveston Bay are available for the period, 1998-2013 and include only the oil spills that are reported to the GLO.

Here are some facts about oil spills in Galveston Bay:

  • Oil spills in Galveston Bay are typically small in volume, averaging a little more than 100 gallons per spill, with the majority of spills consisting of less than 1 gallon.
  • A total of 4,562 spills were reported in the Lower Galveston Bay watershed by the GLO during the period 1998-2013.
  • On average, 275 oil spills occur in Galveston Bay every year. The numbers of spills reported by the GLO each year remain fairly constant over the 15 year period with a maximum of 397 spills reported in 2001 and a low of 184 spills reported in 2011.
  • Shipping vessels are responsible for the greatest number of oil spills in Galveston Bay with 1,866 vessel spills reported versus 981 reported facility spills during 1998-2013.

Prior to the March 2014 oil spill along the Texas City Dike, the largest spill reported in Galveston Bay was a 70,000 gallon facility spill. The spill occurred in June 2000 in the Houston Ship Channel in Harris County and consisted of Bunker C and other heavy fuel oils. The largest oil spill reported from a shipping vessel since 1998 occurred in March 2001 in Galveston Bay in Galveston County. The spill measured 44,100 gallons in volume and was of an unknown type. The March 22, 2014 oil spill is a very large spill resulting in an estimated 168,000 gallons of bunker or marine fuel oil, which would make it the largest oil spill since the inception of the GLO Oil Spill Prevention and Response Program.

In response to changing currents, winds and weather conditions, oil recovery plans have been extended into the Gulf of Mexico and south along Galveston Island. The latest update (March 26, 2014) from the Unified Command states that weather conditions Tuesday pushed oil 12 miles out into the Gulf of Mexico and along the coast in a southwesterly direction. A second Incident Command Post has been established in Port O’Connor to prepare to protect the Matagorda area from oil that may wash ashore.

Data provided by: Texas General Land Office, Oil Spill Prevention & Response