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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The last 12 miles, Day 219

Colin McDonald pours snowmelt, which he collected in June from a snowfield at the headwaters of the Rio Grande in Colorado, into the Gulf of Mexico. Photo by: Dan Reicher

The forecast called for temperatures in the 40s, rain and a 24 mph north wind. The tide was going to turn against us at noon.

The Rio Grande is never a dull place to paddle.

With nine canoes and kayaks ‑ paddled by folks ranging from my brother to people I had never met — we paddled into a headwind that spun the boats as we clawed our way downriver. Ellen Tyma, our host for the last three nights, followed in a Jet Ski to make sure we would make it.

We hugged the banks, which changed from thorn scrub to Gulf Coast prairie to mangroves and, finally, to dunes. 

As the river twisted and turned, we hit every compass point. At times, we slid sideways across the water as the wind and our direction lined up. Other times we dug our paddles into the sandy river bottom to get enough traction to move forward.

It felt more like wrestling than paddling.

But we moved downriver. Oyster beds started to appear. The salinity steadily climbed and then spiked too high to be registered with my gear. 

A lighthouse, which stands less than half a mile from the mouth of the Rio Grande in Mexico, rose above the horizon.

We could see the spray ripped from the waves by the wind and, finally, a break in the dunes. The Gulf of Mexico sat before us, teaming with birds, as the surf roared.

Where the Rio Grande ends is not exact and I was in a daze trying to understand what was happening. Jenna and I found a current of brown river water heading out and paddled against the wind to stay in its flow. 

The water changed from light brown to light green.  The waves built up and they threatened to flip the canoe.

We turned and surfed the waves across the river current back to the beach.  

I took out the vial of snowmelt I have carried from Stony Pass and waded back into the Gulf.  The clear water poured into the brackish foam and was gone.

It’s been decades since snowmelt from the Rockies has reached the Gulf of Mexico here. It was the least I could do to thank the river for such a wonderful ride.  

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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.
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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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