Disappearing Rio Grande

New? Start here.

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.

Read more

Testing the Water, Day 15

Colin takes a water sample from the Rio Grande near the Del Norte gauge. Photo by: Erich Schlegel

In the last two weeks, we have dropped almost 6,000 vertical feet and traveled about 150 miles along the Rio Grande.  The remaining 7,500 feet we have to go will be spread out over some 1,700 miles.

It’s going to be a lot more paddling and walking, and a lot less floating.

To help understand the river better and pass the time, I am taking water samples every afternoon that we paddle.

The tests I’m most excited about are for E. coli.  It’s the most disgusting, because when I have a positive test, it means there is poop in the water.  But it is also one of the most telling indicators about how the land along the river and the river itself are being treated.  A river that is used as a sewer to take away the waste of cities and industry will have a large amount of E. coli. There can be natural sources of E. coli, but nothing like what a leaking sewer pipe or feedlot can produce.

Dr. Robert Metcalf at the California State University, Sacramento developed the procedure I am using and donated the testing materials. His goal is to make water quality testing as easy and cheap as possible so drinking water supplies can be tested before they make people sick.

Polluted water is a big problem. According to the World Health Organization, 1.8 million people a year, mostly children, die from diarrheal diseases, which are most often caused by drinking polluted water.

It’s an issue lower down on the Rio Grande as feedlots and cities start to crowd the river. We will be talking with the Rio Grande International Study Center once we get to Laredo.

But so far, every test has been negative. It's not a surprise, since I have floated mostly through national forest and large ranches.

After Alamosa, there will be another couple hundred miles of mostly undisturbed river and I expect the water will stay fairly clean. But eventually the lucky streak is going to end and Erich and I are going to have to be very careful to not ingest the water. It will add a a new challenge to the paddling.

(Note: My pH and conductivity meter is broken, so the measurements for those two data points are not accurate.)

To comment on this post or ask a question, please visit the expedition's Facebook page.

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 9:03 a.m. 37.53162 -105.95193
#2 9:41 a.m. 37.51519 -105.92442
#3 11:18 a.m. 37.4716 -105.86189


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.


Jessica Lutz
Mike Kane
Project Editor
Barbara Hosler
Copy Editor
News Apps Team Lead | @rdmurphy
Google Journalism Fellow | @jessihamel
Web Designer | @been_hussln
Editor | @ATXjj