Water Quality & River Users

Rio Grande Water Quality: Information for River Users

The quality of water in the Rio Grande through the Big Bend region is highly variable. Big Bend National Park staff sample the water for bacterial levels on a monthly basis at several locations within the park. The samples require 24 hours for incubation, delaying results and preventing timely notification of poor water quality conditions. However, the sample results have shown some trends between river flow levels and high bacteria counts.

The data shows that just after rainstorms, and when flow levels are rising, the bacterial counts rise and may exceed the recommended levels for contact recreation such as swimming. This is likely caused by runoff from creeks and other tributaries carrying animal waste and other pollutants into the Rio Grande. This occurs primarily during the summer monsoon season, between June and October, but can happen at any time of year.

Bacteria, such as Fecal Coliform and E. Coli can cause illness if ingested. Children are particularly susceptible to bacterial infection. Small children are more likely to be exposed through splashing, and otherwise getting river water in their eyes, mouths, ears or nose.

On the other hand, during periods of prolonged low flows, the bacterial levels tend to be very low, and well within safe limits of state standards for recreation. During low flows, the river tends to be high in salts as is common in desert rivers below dams. The high salinity may reduce the amount of bacteria in the water during low flows. Because many of the small communities along the river do not have adequate sewage treatment facilities, there may be bacteria in the water immediately downstream of these towns even during periods of low flow.

People who raft and canoe down the river will probably not be at high risk, however precautions should be taken to reduce the chances of ingesting river water, especially by children.

What precautions should you take on the river?

• Never drink river water
• Boil river water for 10 minutes prior to use for rinsing dishes, etc.
• Disinfect cuts or other open sores after exposure to river water
• Prevent children from immersing their heads in the water or otherwise getting water into their mouth, eyes, ears or nose.

During and soon after high flows and/or rainstorm:

• Avoid prolonged exposure to the river water (i.e. don't spend long periods of time swimming)
• Avoid immersing your head in the water.
• Keep very young children out of the water