A recent example of an effective dip-site identification programme comes from Australia, where international pressure was brought to bear in the late 1980s to eliminate pesticide residues in export beef products. A significant proportion of this pesticide contamination was thought to be derived from cattle-dipping sites. The Government instituted a management programme for cattle-dip sites in 1991 through the Cattle Tick Dip Site Management Committee, and subsequently through NSW Agriculture. Under that programme all dips were identified and, as far as possible, their locations accurately recorded, with details provided to local councils. In addition, dips were audited for such things as proximity to developments, proximity to waterways, adjacent land uses, slope and erosivity; and soil type. This information was combined with other data, such as historical chemical use on a site-by-site basis.
The Cattle-Dip Identification Programme in Australia was unique because most of the dip sites were either owned or leased by state governments and therefore records were available for the location of the dip sites. Properties indicating levels of residue in meat products were placed on trace-back and quarantine programmes, and the dipping sites were identified by information provided by farmers, the Department of Agriculture, and field reconnaissance for associated structures such as concrete plunge dips close to wells. Although this programme involved identifying cattle-dip sites and did not deal with sheep dips, the driving forces and implementation of this programme are relevant to sheep-dip sites in New Zealand.
In Australia, sniffer dogs have also been used effectively to identify a range of organochlorine contaminated sites. In areas where the approximate location of previous sheep-dip sites is known, the dogs are used to locate hotspots of contamination. (See Appendix 8 for more on this sampling strategy and its application in New Zealand.)
In the United States of America, a number of states have used different methods to identify contaminated sites. The Massachusetts Department of Environmental Protection has managed a programme of identifying small-scale contaminated sites by identifying contaminated drinking-water supply wells and backtracking from these wells to find the contamination source. The Oregon Department of Environmental Quality identifies sites by a number of methods, including notification of current spills, citizen complaints, and contamination identified on neighbouring properties.