Disappearing Rio Grande

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Why Follow the Rio Grande

by Colin McDonald | Feb. 11, 2015

The Rio Grande is disappearing. Demand for water is growing as snow packs shrink, rain patterns shift and average temperatures rise faster than they ever have in the past 11,000 years.

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Falcon Dam, Day 200

The sandy soil along the Rio Grande ensures that nothing near the river is ever permanent. Photo by: Colin McDonald

On any given day, a new archeological site could appear along the shores of Falcon Reservoir. The water level is rarely steady and the sandy soil is constantly moving with the shifting water and waves.

“It’s dynamic down here at Falcon Lake,” said Mark Howe, the cultural resource specialist for the International Boundary and Water Commission. “People have been living here for more than 10,000 years … [w]e are just trying to save what we can.”

The reservoir flooded two towns and Spanish settlements dating back to 1767, according to Texas Beyond History. The ranchos the Spanish established were built on top of Indian encampments and started the cattle industry in what would become Texas.

The place is literally littered with history and it is Howe’s job to protect what can be protected, when it is found.

Howe was at Falcon Dam checking on a few projects. He and Juan Uribe, the area operations manager, helped me portage the dam while giving me the lay of the land.

It was too good an opportunity to pass up. I used up all my cushion time for the day talking to them about Falcon Dam and the historic sites farther downstream.

By noon, I was behind schedule and had to race the sun to get to Roma, 16 miles downstream, before dark.

I'm now cruising waters that were once the domain of steam-powered paddleboats and home to small towns that were some of the first settlements in what would become the United States. It’s a place that has been a frontier for more than 400 years.

I just hope I don't get lost in the stories or the shifting sand.  

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Air temperature (°C)
Conductivity (µS/cm)
Depth of Measurement (meters)
Dissolved oxygen (mg/L)
E. coli colonies per 100 ml
pH level
Secchi disk transparency (meters)
Water temperature (°C)

What do these numbers mean?

As they travel, Colin and Erich are taking water samples for the following periodic water quality tests. In partnership with The Meadows Center for Water and the Environment’s Texas Stream Team Program at Texas State University, the results will be added to a public database it helps maintain for research and monitoring water quality.

Air/Water Temperature
Temperature impacts everything from the amount of oxygen in the water and the metabolism of aquatic species to how easily compounds dissolve. Most species can tolerate slow seasonal changes but can go into thermal stress or shock when temperatures change by more than one or two degrees Celsius in 24 hours.
pH Level
The pH scale measures water’s acidity and runs on a logarithmic scale from 1.0 to 14.0, with 7.0 considered neutral. Anything below 7 is acidic and anything above is basic. A pH range of 6.5 to 8.2 is optimal for most organisms.
Dissolved Oxygen
Oxygen is just as vital for life below the surface as it is above. The amount needed varies according to species and stage of life, but generally 5.0 to 6.0 milligrams per liter is required for growth and activity. Levels bellow 3.0 mg/L are stressful to most fish species and levels below 2.0 mg/L for an extended period of time will cause fish kills.
Conductivity levels depend mainly on how easily the rocks and soils a stream passes through dissolve. For example, high levels of conductivity are often found with water that passes through limestone and gypsum because it will pick up the calcium, carbonate and sulfate from those rock formations. However, discharges into a water body, such as a failing sewage system, can also raise the conductivity because of the presence of chloride, phosphate and nitrate.
Water Clarity
Turbid water can come from high levels of sediment or plankton. Both will block sunlight to aquatic plants and the sediments can carry pollution such as nutrients and pesticides. Low levels of turbidity may indicate a healthy and well-functioning ecosystem. High levels can be an indicator of runoff from eroding soils or blooms of microscopic plankton due to high levels of nutrients.
E. coli
E. coli bacteria are found in the colon of warm-blooded animals. If the pathogen is found in water it’s an indicator that fecal mater from humans, pets, livestock or wildlife is also present and may pose a public health threat. For drinking water the standard is to have no E. coli. But almost all non-treated water has some E. coli in it and at low levels it does not represent a substantial health threat to those who swim or wade in it. The Environmental Protection Agency has set the water quality standard for these types of activities at 126 colony forming units per 100 mL.
Secchi disk transparency
The Secchi disk is a plain white, circular disk used to measure water transparency in bodies of water. It is lowered into the water of a lake or other water body until it can be no longer seen. This depth of disappearance, called the Secchi disk transparency, is a conventional measure of the transparency of the water.

While making his way to the Gulf of Mexico, Colin will be periodically activating a device that uses satellite technology to share his current location. Use this map to see where he traveled on this day.

Check-In Time of Check-In (CST) Latitude Longitude
#1 11:30 a.m. 26.55791 -99.16122
#2 11:34 a.m. 26.55933 -99.1671
#3 12:09 p.m. 26.54558 -99.17102
#4 12:17 p.m. 26.54558 -99.17113
#5 1:11 p.m. 26.53343 -99.15872
#6 1:57 p.m. 26.51456 -99.11658
#7 4:06 p.m. 26.42812 -99.11166
#8 6:07 p.m. 26.40367 -99.01931


To report on and understand the haphazard irrigation system the Rio Grande has become and the changes it is going through, Colin decided the best approach would be to travel the length of the Rio Grande by foot and small boat.

He knew it would give him a unique perspective on a river that few understand. It did require many long days of moving slowly and camping on muddy riverbanks, but Colin likes that sort of thing.

The benefit was it provided access to people who wanted to share their stories and experiences with the Rio Grande. Via Facebook and chance encounters, Colin made instant friends who opened their homes. They provided help from loaning their trucks to their cell phone contact lists to help tell the story of the Rio Grande.

The trip would not have been possible without their help, along with the dedicated assistance of David Lozano, Jason Jones and Daniel Dibona, who drove thousands of miles to get people and boats in place.


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