Escherichia coli and Campylobacter in two conventional Waikato dairy farm effluent ponds

Abstract

Escherichia coli and Campylobacter were measured in the influent and effluent at two conventional dairy farm ponds (PS I and PS II) that discharged to surface water. Pond treatment reduced concentrations of both bacteria by about two orders of magnitude. From September to December both ponds discharged continuously at average rates of 0.235 L s−1from PS I and 0. 211 L s−1from PS I. Bacterial discharge, on a per cow per day basis, was 6.7×107 E. coli and 8.6×105 Campylobacter from PS I and 3.0×108 E. coli and 2.8×106 Campylobacter from PS II. Later in the season effluent discharge declined, fewer cows were milked but bacterial loads remained high at 1.2×107 E. coli and 1.7×104 Campylobacter cow−1 d−1. These findings demonstrate the unsatisfactory microbiological quality of pond effluent and that discharge to surface water is a poor option.