Water quality in cattle feedyard playas in winter and summer

Objective-To determine the impact of feedyards on endotoxin concentration, fecal coliform count, and other water quality measurements during winter an d summer in feedyard playas (shallow lakes). Sample Population-Water samples obtained from 7 feedyard playas and 3 nonfe edyard control playas. Procedure-Surface water samples were collected from each playa and at vario us depths from 3 feedyard playas. Endotoxin concentrations, 22 water qualit y variables, and fecal coliform counts were determined in samples collected in summer and winter from various combinations of playas. Results-Cattle numbers per feedyard ranged from 40,000 to 175,000 head/y. M ean endotoxin concentrations were significantly lower in control playas tha n in feedyard playas in winter and summer. Endotoxin concentration appeared to be homogenous at various water depths. Values for 20 of 22 water qualit y variables were higher in the feedyard playas than in control playas in wi nter and summer. In winter only, mean total fecal coliform concentration in feedyard playas was significantly greater than in control playas. Conclusions and Clinical Relevance-Results indicated that feedyards have th e potential to impact water quality in playas, and cattle should not be all owed access to them. Feedyard playa water should not be used under high pre ssure to settle dust in pens with cattle or to cool cattle, because aerosol s containing pathogens and high concentrations of endotoxin are a health ha zard for humans and cattle.