Rebirth of the Bahia Grande, Texas

Rebirth of the Bahia Grande: Partners Working Together to Restore an Estuary

A sea of partners are working together to restore the Bahia Grande estuary. The effort began in 2000 when the Laguna Atascosa National Wildlife Refuge acquired 21,700 acres of land between the towns of Laguna Vista and Brownsville, Texas.

 

The 10,000-acre Bahia Grande wetland complex consists of three shallow water basins: Bahia Grande, Little Laguna Madre, and Laguna Larga.  Historically, these embayments were connected to the tidal waters of the nearby Laguna Madre and provided productive bay nursery habitat for fish and shellfish such as red drum, black drum, gulf menhaden, spotted seatrout, American oyster, white and brown shrimp, southern flounder, and blue crab.  The shallow bay waters and intertidal wetlands and mangroves also provided important habitat for birds such as pelicans, piping plovers, terns, gulls, and redhead ducks. 

Unfortunately, the placement of dredged sediments from the construction of the Brownsville Ship Channel in the 1930s and the construction of State Highway 48 in the mid-1950s cut off all tidal flow to the Bahia Grande.  The “Big Bay” estuary became a dry, barren dust bowl that no longer supported fish and wildlife habitat.  Robbed of its life giving water, salty dust blew over the drained landscape causing respiratory health problems  for nearby residents and schools, damaging metal structures such as air conditioning and heating units, and causing wildfires through short circuits on power line transformers. 

In 2005, a small 60-foot wide channel was constructed between the Brownsville Ship Channel and the Bahia Grande to reintroduce ocean waters from the Laguna Madre back into the basin.  Immediately, bay waters flowed into and refilled the barren dry landscape alleviating the blowing dust and allowing fish to return to the Bahia Grande.

Before and after excavation of an initial pilot-project channel; 
partially restoring hydrology and flooding to the Bahia Grande.

(Photo credits unknown.  Source:  NOAA Fisheries Image Gallery)
http://www.nmfs.noaa.gov/gallery/images/photos/5577080775.html & http://www.nmfs.noaa.gov/gallery/images/photos/5577666744.html

The small channel was a critical start to restoring the mighty Bahia Grande estuary, but the pilot-project channel is not large enough to provide adequate circulation of water into and out of the basins.   After additional study and design, partners have now obtained funding necessary for the Brownsville Navigation District to enlarge the 60-foot wide pilot channel to a 225-foot wide "Main Channel".  This larger channel will increase the amount of water exchange into the Bahia Grande thus lowering salinities which will allow for growth of key wetland, mangrove, and oyster reef habitats that require more moderate salinity levels necessary for their survival.  However, funding limitations would have resulted in the placement of the sediment excavated to widen the channel into approximately 22 acres of existing valuable tidal wetlands, mangroves, and sandflats located adjacent to the channel. 

Through the essential fish habitat consultation review process, the NOAA Fisheries’ Habitat Conservation Division was able to work with other partners including the Texas General Land Office, the Texas Parks and Wildlife Department, the U.S. Fish and Wildlife Service, and the U.S. Army Corps of Engineers to identify a solution and the additional restoration funding necessary to allow for the excavated material to be disposed of in an existing upland placement area.  This alternative will allow this critical restoration of fish habitat to proceed while also avoiding collateral damage to existing productive wetlands.  This win-win solution is a good example of partners working together across multiple programs and organizational boundaries to successfully leverage Gulf restoration funding and expertise to implement critical habitat protection and restoration action to the benefit of coastal ecosystems and communities.

Mangroves and wetlands avoided by utilization of upland dredge material disposal site as an alternative to filling valuable coastal habitat.

(Photo taken by Kristopher Benson, NOAA, March 2015.)
 

For more information about the Bahia Grande Project contact:  Heather Young

GLOSSARY:

Estuary - a body of water formed where freshwater from rivers and streams flows into the ocean, mixing with the seawater. Estuaries and the lands surrounding them are places of transition from land to sea. Thousands of species of birds, mammals, fish, and other wildlife depend on estuarine habitats as places to live, feed, and reproduce.

Wetland complex – a wetland is defined as land or areas (such as marshes, estuaries or swamps) that are covered often intermittently with shallow water or have soil saturated with moisture. Different kinds of wetland arise due to a few key factors, principally water levels, fertility, natural disturbance and salinity.

Water basin – an extent or an area of land where surface water from rain converges to a single point at a lower elevation and usually the exits of the basin, where it joins another waterbody, such the ocean

Dredging – is an excavation activity usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments, removing them, and disposing of them at a different location. This technique is often used to keep waterways navigable for boat traffic.

Sediment - the accumulation of sand and dirt that settles in the bottom of a water body such a a bay or lake.Channel - a narrow body of water between two land masses or a natural or man-made deeper water course through a bay or any shallow body of water.

 

NOTE:  Bahia Grande project location map courtesy of U.S. Fish and Wildlife Service.