The Arkansas River is a major river system in the central United States, beginning in the Rocky Mountains of Colorado and flowing through Kansas, Oklahoma, and Arkansas before joining the Mississippi River. The river’s status is not uniform across its entire length, but scientific data does indicate a significant, long-term reduction in flow, particularly in its western reaches. This reduction reflects a genuine public concern about the health and sustainability of this heavily utilized waterway.
Current Hydrological Status
The overall condition of the Arkansas River is marked by flow deficits when compared to historical averages. Data from the mid-20th century show a dramatic reduction in water volume in the central plains; for example, the average flow in central Kansas dropped from approximately 248 cubic feet per second (cfs) between 1944 and 1963 to just 53 cfs in the period from 1984 to 2003. Recent studies project this trend of declining water availability will continue throughout the 21st century, with climate change scenarios suggesting the river’s flow could decrease by 12% to nearly 28% by the end of the century. This reduction is already manifesting as below-average flow conditions and intermittent drying in certain segments.
Geographic Variation in Water Levels
The term “drying up” applies most accurately to the river’s western, unregulated segments, but it does not describe the condition of the entire 1,469-mile-long river. After the river leaves the mountains, its status changes dramatically as it crosses the plains. The segment that enters Kansas from Colorado often becomes a mere trickle or disappears entirely for long stretches, especially during dry seasons. The river’s eastern half, flowing through Oklahoma and Arkansas, is a different system due to intensive management. This downstream portion is maintained as the McClellan-Kerr Arkansas River Navigation System (MKARNS), a series of locks and dams. Major reservoirs like Keystone Dam in Oklahoma and John Martin Reservoir in Colorado regulate flow, ensuring a minimum depth for commercial traffic and water supply further east.
Primary Factors Contributing to Low Flow
The reduction in flow is a result of both natural climate patterns and high rates of human water usage. Natural factors include long-term drought conditions and a decline in the mountain snowpack, which is the primary source of the river’s headwaters. Warmer temperatures lead to earlier snowmelt, which alters the timing of peak flow and contributes to lower summer water levels.
Human diversion is equally significant, with agricultural irrigation and municipal use accounting for massive water withdrawals. This high demand is legally managed by agreements like the Arkansas River Compact of 1948, which apportions the water between Colorado and Kansas. This interstate compact has been the subject of litigation, with Kansas successfully arguing that high-capacity irrigation well pumping in Colorado depleted the river’s flow, violating the agreement. The selling of water rights from agricultural users to growing cities in the region has also contributed to the drying up of historically irrigated farmland, further reducing the amount of water available.
Consequences for Ecosystems and Human Use
The reduced flow has severe consequences for both the natural environment and human economic activities. In the river’s western segments, the intermittent drying destroys riparian habitats and contributes to a decline in biodiversity. Lower water volumes lead to higher water temperatures, which stresses or kills temperature-sensitive aquatic life, as the lack of flow and shade from degraded riparian zones reduces the river’s ability to cool itself.
For human use, low flow conditions challenge the sustainability of agricultural practices and recreational activities. The commercial navigation system (MKARNS) in Oklahoma and Arkansas is also affected, with recent periods of low water contributing to a sharp decline in commercial shipping tonnage. This reduced navigability impacts the economical transport of bulk commodities like agricultural products and fertilizer, affecting the regional economy.