Middle RGV Exploring the Rio Grande Delta

The Middle Rio Grande Valley’s terrain consists of more flat topography that is abundant in tamaulipan thorn scrub.  The majority of the native habitat was cleared during the latter parts of the 19th century and early 20th century for agriculture production.  The first stop on this field trip was a nature park of Estero Llano Grande in Weslaco, Texas.  Estero Llano Grande is a reminder of how the early settlers would have encountered the terrain within the area.  Within the the nature park were native grasses, trees, avian, and other biota.  It was truly a serene environment for one to go take in the beauty the RGV has to offer.

 

Sites visited during the exploration of the Rio Grande Delta on July 15, 2015.  Sites are flagged.  

Entrance to Estero Llano Grande Park.
The palm fronds overlooking the pathway from the left side are from the native Texas Sabal Palm Sabal texana.

At Estero Llano Grande park overlooking a wetland, ideal habitat for migrating avian.  

Eastern Cottontail Sylvilagus floridanus in the center of this picture at Estero Llano Grande park.

The second pit stop was part of the watershed draining into the head of the Arroyo Colorado.  The surrounding landscape upland was mostly urbanized and cleared for agriculture.  Here the Arroyo Colorado receives water from agriculture runoff, irrigation out flow, and municipal waste water effluent.  

Arroyo Colorado headwaters flagged on the lower left of this map and Estero Llano Grande park adjacent.

Educator's graduate class receiving experiential learning lecture from Professor Dr. Reynaldo Ramirez at the headwaters of Arroyo Colorado.  There students identified the flow of freshwater from upstream Arroyo Colorado to the mouth flowing into the Laguna Madre.  Students also learned that the main source of water to the arroyo comes from municipal waster water effluent and farm irrigation outflow.  

Looking downstream the head of the Arroyo Colorado.  Cattail plants of the genus Typha on the lower left in photo.

 The third and fourth final stops were at the highway 574 bridge near the Port of Harlingen and Rio Hondo lift bridge respectively.  

Map of the third and fourth pit stop in the Middle RGV field trip.

Students going down to the banks of the Arroyo Colorado under highway 574 bridge.  The Port of Harlingen's main produce is agriculture products, such as sorghum, corn, soybean, and sugar.  In the background are the grain silos at the port.  

Lift bridge at Rio Hondo, Texas allowing passage of barges with goods to be exported.

Pulleys used to lift the bridge.