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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Just Enough Rain for Rainbows, Day 18

A double rainbow forms as an afternoon rainstorm passes over the San Luis Valley. Photo by: Colin McDonald

Mike and Marilyn Willett have run a cattle ranch at the south end of the San Luis Valley since 1971.  Their herd is usually about 450 head, but the persistent drought has made them slim that number down to 350.

Although they are dependent on surface flows to flood irrigate their hay fields and have seen springs dry up as the aquifer drops, Mike is not quick to blame farms that pump groundwater.  He has served for more than 25 years on water boards across the valley and has lived through the history that shapes the current issues.

“It’s just hard to quantify how much harm the wells have done and how much harm the drought has,” he said. He points out that the aquifer did not start to drop significantly until the drought started in 2002.

But he is not jealous of his neighbors and their wells.  One is running a tilapia fish farm with the warm water of an artesian well.  With the formation of sub-districts, such well owners will be charged for that pumping.

“They have been on a free ride,” Mike said.

Mike points out that drought and new regulations are nothing new for the valley.  Down the road from his home is a small acequia community; the acequia is a communally owned and operated ditch.

Mike explained that members of the community thought they had it good because they were the only ones who drew from a reliable spring.  They were late to register their water right and when the Rio Grande Compact was set in 1938, it was determined their spring was needed for part of the water deliveries to New Mexico.  Suddenly, what was considered a secure water right was not. 

Now the community is nearly gone.  Hay fields have replaced the labor-intensive fields of vegetables that once supported families and required reliable water.

Such is life in a valley where enough rain to keep the dust down on the road is noteworthy.  And rainbows — like the one pictured above that we saw while driving around the Willetts' ranch — form in rainstorms that never touch the ground. 

Tonight, I am camping on the Willetts' ranch near the confluence of the Conejos River and the Rio Grande.  I can hear horses crashing through the cottonwoods near the gravel bar I am sleeping on.

Tomorrow, I’ll paddle through a combination of private and public land where Mike estimates some 300 such horses live.  The herds, made up of abandoned animals, are a constant problem as they destroy grazing lands and outcompete native animals.

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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 1:56 p.m. 37.30703 -105.73851
#2 2:09 p.m. 37.3031 -105.73798
#3 7:24 p.m. 37.3031 -105.74147


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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