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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Railroad tunnel to the Pecos, Days 149 and 150

The view from one of the side tunnels leading between the cliff edge over the Rio Grande and the main tunnel that carried the railroad. Along the Rio Grande, you can see the high water mark left by the changing level of the lake. Photo by: Colin McDonald

The railroad had a problem when it got to the Pecos River. The gorge was too deep and too wide for a bridge. It would take too long to go around to the north. The tracks had to go around to the south and cross the mouth at the confluence with the Rio Grande.  

The only problem was the tracks would have to parallel and then climb the cliffs. The solution was two tunnels that would carve through the sides of the cliffs and allow the tracks to reach from the high plateau to the riverbed.  

Eventually, the highest railroad bridge in Texas was built over the gorge and the tunnels were abandoned. They can be seen from Amistad Reservoir, along with the remains of the small town that sprung up as they were built. 

I could not resist the climb up to check them out. The west tunnel is nearly a half-mile long with two side tunnels cut out to the cliff edge that overlooks the river.  

Inside, it smelled of bat guano and the floor was covered in several inches of black dust. A partially mummified goat was near the east entrance. A herd of at least 50 were scattered along the cliffs of the east entrance and their constant calls to each other echoed through the tunnel.  

From there, it was a short paddle to the confluence of the Pecos River. The supports of the old railroad bridge are buried under mud — as is just about everything else. We camped at the base of the cliffs on the firmest ground we could find.    

Our challenge was we needed to get out of the Rio Grande and about a half mile up the Pecos River to the boat ramp. That was our rendezvous for a side trip to the Devils River to look at how spring flows keep it the cleanest river in Texas and how those flows impact the water quality of the Rio Grande. 

In between the Rio Grande and the Pecos is a half-mile wide berm of mud created by the two rivers coming together and being periodically submerged by the rising waters created by Amistad Reservoir.  

On the Rio Grande side, the mud is pretty hard and cut by the river so getting out only required a few quick steps. We were then able to build a pier of reeds over the soft mud to unload the canoe.  

But on the Pecos side of the berm, the mud is made of the finest of sediment and goes from hard and slick to a pudding that is too thin to support weight but just thick enough to make paddling nearly impossible.  

After four hours of construction using stones tossed down from the cliff and bundles of dried reeds, we had a second pier and were across the mouth of the Pecos.  

Thrilled to be away from the mud and minutes away from climbing into the cab of a heated pickup, we noticed there were quite a few dead fish floating in the water.  

Then we noticed there were hundreds of dead fish. Longnose gar, sunfish, crappies and chad had all gone belly up.  We did not see any catfish. The dissolved oxygen levels were low enough to kill fish, but it was odd that so many of the gar would have died. They can handle low oxygen levels and can breathe air when necessary.  

A fisheries biologist from the National Park Service showed up to take samples, but did not have any conclusions. The Texas Commission on Environmental Quality was also notified and would do its own investigation.  

I’ll follow up with them later this week.  

I’m looking forward to seeing the Devils. I’ve had enough of mud and dead fish for a while.

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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 9:16 a.m. 29.70093 -101.37238


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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