Streamgaging in New Mexico

Most Valencia County residents end up crossing the Rio Grande regularly, and will have observed that river changing from wide and deep waters to dry riverbeds.

River flow rates in the Southwestern United States are well known to vary widely, and the federal government understood in the late 1800s the need to quantify river flows. The United States Geological Survey pioneered streamgaging right here in New Mexico.

In 1889, the USGS established the first streamgage on the Rio Grande in Embudo, N.M. There, the first team of hydrographers (mostly fresh graduates from East Coast colleges) were to be trained in new techniques to measure water flow systematically. This was organized by John Wesley Powell, the second USGS director and of Grand Canyon expedition fame.

That initial attempt at Embudo failed due to improper equipment and hard conditions, but the techniques and equipment improved over time, and today the USGS operates a nationwide network of more than 8,400 year-round, real-time streamgages.

WaterWatch(waterwatch.usgs.gov) is a USGS website that displays maps, graphs and tables describing real-time, recent and past streamflow conditions for the United States. The real-time information generally is updated on an hourly basis.

Two streamgages document the Rio Grande’s flow across Valencia County: USGS08331160Rio Grande near Bosque Farms, and USGS08331510Rio Grande at State N.M. 346 near Bosque, which have been collecting data for more than 15 years. The two gages illustrate the variations due to the seasons, the water management by the Middle Rio Grande Conservancy District, and the wide agricultural water usage in the vicinity of the river in Valencia County.

At the southern gaging station, from August 2023 to August 2024, the river’s level varied by 5 feet, with a flow rate from 8 cubic feet per second (cfs) in October 2023 to 2,800 cfs in late April 2024 when some kayakers were seen cruising down the river between the Los Lunas and the Belen bridges.

The next column will present the challenges of designing a bridge over the Rio Grande in Valencia County.

(Paul Parmentier, a certified professional geologist retired from California and living in Los Lunas, shares the rich geologic features in Valencia County. He earned a Bachelor of Science degree in geology from Belgium and a master’s degree in geochemistry from Japan. The Geology Landscapes of Valencia County are featured monthly.)