title: Water quality in cattle feedyard playas in winter and summer.
abstract: OBJECTIVE
  To determine the impact of feedyards on endotoxin concentration, fecal coliform count, and other water quality measurements during winter and summer in feedyard playas (shallow lakes).
  
  
  METHODS
  Water samples obtained from 7 feedyard playas and 3 nonfeedyard control playas.
  
  
  METHODS
  Surface water samples were collected from each playa and at various depths from 3 feedyard playas. Endotoxin concentrations, 22 water quality 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. Mean endotoxin concentrations were significantly lower in control playas than in feedyard playas in winter and summer. Endotoxin concentration appeared to be homogenous at various water depths. Values for 20 of 22 water quality variables were higher in the feedyard playas than in control playas in winter and summer. In winter only, mean total fecal coliform concentration in feedyard playas was significantly greater than in control playas.
  
  
  CONCLUSIONS
  Results indicated that feedyards have the potential to impact water quality in playas, and cattle should not be allowed access to them. Feedyard playa water should not be used under high pressure to settle dust in pens with cattle or to cool cattle, because aerosols containing pathogens and high concentrations of endotoxin are a health hazard for humans and cattle?
authors.affiliation: Animal Waste Resources, Agricultural Research Service, United States Department of Agriculture, Bushland, TX 79012, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Purdy
authors.forename: D C
authors.initials: DC
authors.lastname: Straus
authors.forename: D B
authors.initials: DB
authors.lastname: Parker
authors.forename: B P
authors.initials: BP
authors.lastname: Williams
authors.forename: R N
authors.initials: RN
authors.lastname: Clark
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D004731:Endotoxins / Q000032:analysis*; D004755:Enterobacteriaceae / Q000254:growth & development*; D005243:Feces / Q000382:microbiology*; D016014:Linear Models; D012621:Seasons; D014871:Water Microbiology
chemical_list: D004731:Endotoxins