Reviving the Arkansas River

“Saline water is contaminating the Ark River valley,” says Whittemore.

CONTENTS

Arkansas River–page 1

From the Director–page 2

New Publications–page 3

Earth Science Videos–page 3

A Place To Visit–page 4

Drive over the Arkansas River bridge on the south edge of Dodge City, and you’ll see a river bed filled with tumbleweeds and sand maybe marked by tire tracks and foot prints. What you won’t see, unless you’re real lucky, is water.

Most Kansans know that the state recently won a decade-long legal battle with Colorado over the amount of water that Colorado takes from the river. But reviving the Ark won’t be as simple as just adding water. The quality of water in the river is equally important. Don Whittemore, geohydrologist at the Kansas Geological Survey, is analyzing variations in the quality of Ark River water.

When the Arkansas leaves the Rocky Mountains in Colorado, its water is clear and clean. By the time it enters Kansas, the water is slightly salty. That’s been true since the late 1800’s, shortly after ditches were built to divert water from the river for irrigation. The water that moved over the fields and back into the river (known as return flow) was slightly salty, because evaporation concentrated the salt. When large reservoirs were built on the Arkansas in Colorado in the mid-1900’s, evaporation increased and salinity got worse.

Today, even in dry times, small amounts of water are released into the river from Colorado’s John Martin Reservoir and from return flows in eastern Colorado. This maintains streamflow as far west as Syracuse, in Hamilton County. Between Syracuse and Garden City, around the town of Lakin, the river disappears (it begins to flow on the surface again near Great Bend). The Ark dries up after Lakin because some water is drained away by local irrigation ditches. The rest seeps out of the river channel and into adjacent beds of sand and gravel, called the High Plains aquifer. Ground-water pumping, mostly for irrigation, has lowered water tables in the aquifer, causing the slightly salty water to move from the river into the aquifer.

The salinity problems also occur in wetter times. In July 1995, snow-melt in the Rockies and heavy rains caused the Ark to flow all the way through western Kansas. Whittemore found that the water was fresher than it was during dry times, but still slightly salty from Coolidge to Dodge. Again, that slightly saline water moved out of the river and into the aquifer. “Saline water is contaminating the Ark River valley,” says Whittemore.

Salinity may not stop the use of that water for irrigation—“slightly saline water is better than no water,” says Whittemore—but it may be salty enough to cause problems for other uses. At Garden City, for example, high-quality ground water is necessary for manufacturing, for meat packing, and for domestic and industrial uses.

In addition to analyzing river water, Whittemore has compiled historical measurements of the river’s water quality and checked water from neighboring wells. “We need to document where the saline water is, how fast it’s moving, and what kind of steps you can take to ameliorate the salinity,” says Whittemore. To help do that, Whittemore is planning more water sampling of the river and neighboring wells and is developing computer models of the water’s movement. He also plans to drill test wells that will tell more about the local geology.

In the meantime, any additional releases of water from Colorado may help dilute the salinity. “With proper management, these new releases should be less saline,” says Whittemore. “But they won’t be completely fresh, and we’ll still have the problem.”

Whittemore’s research is funded by the Kansas Water Plan and is done in cooperation with the Kansas Water Office, Division of Water Resources and Division of Plant Health of the Kansas Dept. of Agriculture, Groundwater Management District #3, the Kansas Dept. of Health and Environment, and the Southwest Kansas Local Environmental Planning Group.

Online February 10, 2003

Comments to: lbrosius@kgs.ku.edu

Kansas Geological Survey

URL:http://www.kgs.ku.edu/Publications/GeoRecord/1996/vol2.2/Page1.html