DWR Currents Extra

February 26, 2010

Ark River Flow Reaches Garden City

For the first time in eight years there is river flow at Garden City.  That is, when the river is not frozen.

Sustained Arkansas River flow was detected at the U.S. Geological Survey gage at Garden City beginning February 13, tapering off intermittently when the river froze.  The daily average flow rate climbed as high as 11 cubic feet per second (cfs) by February 25.

While 11 cfs is a proverbial drop in the bucket compared with the maximum recorded flow of 104,000 cfs at this location in June 1965, any sustained river flow at this location has been a rare occurrence in recent years.  Apart from short-lived runoff from local precipitation events, the last time river flow from Colorado made it to the Garden City gage was in March 2002.

One of the reasons river flow is not regularly occurring at Garden City is because upstream ditch companies with very old water rights normally divert for irrigation use the 100 cfs to 200 cfs typical state line flows from Colorado in recent years, even in the off-season when it is stored in Lake McKinney or used to improve soil-moisture for the coming irrigation season.  Another reason is that when some flow makes it past the ditches it usually soaks into the alluvium – the sandy river bed where water levels have dropped due to pumping – rather than flowing downstream.

The fact that river flow is currently reaching Garden City is due primarily to the fact that off-season flows have been bypassed while Lake McKinney dam is being repaired.  Recent precipitation events have also limited the need for diversion of river flows by irrigation ditches for winter irrigation.

As a result the river flow has recharged the alluvium to the point where there is some flow at Garden City when temperatures are above freezing for sustained periods of time.  It will be interesting to see whether the flows increase this spring, and how far downstream the flow may progress.