by S.T. Paxton
A Passing Storm on the Cimarron River
The Path of the Cimarron River
The Cimarron River is one of the least regulated rivers in the State of Oklahoma. Historically, a few stretches of the river in the Oklahoma Panhandle have been diverted for irrigation during the growing season. Aside from these diversions, the river has no major dams or impoundments located along its course until reaching Keystone Reservoir where the river meets and becomes the Arkansas River. Water quality is one of the main reasons the water in the Cimarron River has remained relatively intact. Salt and gypsum layers occur naturally in portions of the red rocks that make up much of the Cimarron River Valley. Because small portions of these minerals dissolve in water, the river water is less desirable for irrigation or municipal water supply. Ironically, the perception of poor-water quality and lack of interest from commercial entities has helped the river maintain much of its natural heritage.
Finding the path of the Cimarron River in the vicinity of the Oklahoma panhandle is not quite as easy as looking at a map – some of the following details are not on a map! In fact, you have to know someone who has lived in the area of the river for an extended period of time to piece together the course of the Cimarron in the vicinty of the Oklahoma panhandle. This uncertainty in the course of the river is because the river is dry most of the year – in fact, the river is called the “Dry Cimarron” in New Mexico and far western Oklahoma.
The headwaters of the Dry Cimarron River are located in northeastern New Mexico between the town of Folsom and Capulan Volcano National Monument. As the crow flies, Capulan is about 53 miles from the western border of the Oklahoma panhandle. The Dry Cimarron enters Oklahoma just a few miles to the west of the small town of Kenton, the county seat of Cimarron County, Oklahoma. From the headwaters in New Mexico to Kenton the river runs on the south side of an erosional escarpment known as Black Mesa, an extensive series of lava flows originating in Colorado. On top of the lava flows in Oklahoma is located the Black Mesa Nature Preserve and a marker indicating the highest elevation in the State of Oklahoma at 4,973 feet. From Kenton, the river heads east in Oklahoma and then northeast through the extreme southeastern corner of Colorado and southwestern corner of Kansas. This reach of the river in Kansas is relatively straight and borders on the Cimarron National Grassland. North of Hugoton, Kansas, the Cimarron River makes a large meandering loop and heads southeast toward Oklahoma. This particular segment of the Cimarron River in Kansas is significant in terms of the Cimarron River flow levels and water quality.
In the vicinity of US Route 54 between Liberal and Kismet, Kansas, the river flows across a geological contact between rocks that make up a part of the High Plains Aquifer and the red, Permian-age common to the southern midcontinent. At and near this contact between the two bodies of rock, fresh water (groundwater with low levels of total dissolved solids) leaks out of the High Plains Aquifer into the Cimarron River. From this point in Kansas and southeast into Oklahoma to a point near Freedom, groundwater makes a continuous and sustained contribution to the levels of total water flow and water quality. In contrast to flow contributions from the High Plains Aquifer, groundwater and surface water in contact with the Permian red beds tend to have lower water quality. The minerals halite (or common table salt) and gypsum (the mineral used for making wall board and plaster of Paris) are common to some intervals of the Permian red beds. These minerals are also easily dissolved by water and contribute to the elevated total dissolved solids in the river water. In the geographic areas of Kansas and Oklahoma where the base of the Cimarron river channel has eroded down into Permian rocks containing layers of halite and gypsum, the quality of the water changes disctinctly relative to water leaking from the High Plains Aquifer.
As the Cimarron approaches Oklahoma, the river flirts with the state boundary for a few miles before plunging south into Oklahoma for good. To the north of Freedom, Oklahoma, the Cimarron continues to gain water in the channel from groundwater with elevated total dissolved solids. A salt works and processing plant is located in Freedom.
Changing Appearance of the Cimarron River
The appearance of the Cimarron River varies with sunlight and water level (referred to as “stage”). Sunlight varies with the seasons, time of day, degree of cloud cover, and distribution of clouds. Water level in the river varies with the occurrence of rainfall (or precipitation events, and lack thereof) and wind conditions.
In large part, the most noticeable changes in the appearance of the river with time are related to the constant change in the volume and direction of water flowing in the active river channel. As a result, most of the daily changes witnessed from the riverbank are a response to rainfall events and the subsequent rise and fall of the water level in the river. For instance, a rainfall event as small as 0.1 – 0.2 inches within the Cimarron River watershed between Coyle and Guthrie, Oklahoma, will result in a rise in the river water level of about 2 to 3 inches over the few days following the precipitation event. Once the water level in the river begins to increase, the increase or rise in water level occurs rapidly. The decrease or fall in water level also occurs rapidly, but more slowly than the increase or rise in the water level. Each time the river level increases a small increment, a small portion of the sand and mud in the active channel is resculpted.
Typically, a layer of mud deposited on top of a now-emergent sand bar will form “mudcracks” and “mud flakes” or “mud curls”. The cracking of the mud is a result of evaporation – as water evaporates, the mud volume decreases in thickness and lateral extent in proportion to the volume loss of water. As the sun continues to bake the mud, the top surface forms an interlocking mosaic of uniformly sized polygons. With additional evaporation, the edges and corners of the mudcracks may curl upward to form mud curls or flakes. The curling of the mudcracks is a consequence of differential moisture content in the mud polygon, that is, water in the upper-most surface of the mud in contact with the atmosphere evaporates more quickly than the water present deeper in the layer. Continued lateral contraction of the mud surface in each polygon causes the top of the mud polygons to curl on the edges to form mud flakes. The mud cracks and mud flakes remain as long as the land surface is dry. These delicate features will disintegrate during a healthy rainfall event.
Another major factor that shapes the appearance of the river on a daily basis is the wind. Windy conditions accelerate the evaporation of water from the emergent sand and mud deposits. The wind also promotes the development from sand of ripples and dunes on the surface of the bars and river banks.
A less recognized consequence of persistently windy conditions over the course of a few days is the development of water waves that collide with and erode the sand bars. These water waves resculpt the appearance of an emergent sand bar by locally eroding and redistributing the sand on the margin of a windward-facing bar. Collision of the water waves with the bar has a tendency to “pile-up” water on the margin of the bar. As the water laps up onto the bar, erosion undercuts the margin of the bar by a few inches and sand collapses down into the water.
In addition to removal of sand from the margin of the bar, continuous oscillation of the water level in response to wind-driven water waves will carve lineations along the side of the bar. These lineation marks are above and parallel to the current water level. Under special weather conditions, a series of vertically arranged or “stacked” lineation marks may form on the side of the bar. These lineations give the false impression that the water level in the river has dropped incrementally or in pulses, such as would be expected from timed releases of significant volumes of water from a reservoir located down river. Instead, the vertically stacked lineations reflect changes in persistent wind conditions as the overall water level in the river drops slowly (but continuously) over the course of several days.
During or immediately after a small rainfall event, persistently windy conditions can result in the formation of “sand stringers” on the tops of sand bars. Wind-driven water waves push a volume of sand back up and onto the top of low-lying water-saturated margins of the sand bar. As the water level in the river channel declines (after a few days), the stringers of sand remain (in isolation) on top of the sand bar. A series of windy days coupled with an overall drop in water level can leave a series of these sand stringers distributed across the upper surface of the bars.