Buffer zones are used to protect streams and adjacent property from the movement of sediment from clear felling activity. A buffer zone, in the traditional sense, is a strip of natural forest, say 50m wide, that is left beside water courses, roads, adjacent properties etc. to protect water from sediments in run off and to provide visual amenity.
Barton and Davies (1993) reported a relationship between concentrations of Atrazine in stream water following aerial application and site characteristics. Atrazine concentrations on the day of spraying were strongly negatively correlated with buffer width. In other words, the larger the buffer zone, the smaller the concentration of biocide in adjacent waterways.
Barton and Davies are suggesting that buffer zones are useful in protecting areas not intended to be sprayed from aerial drift of the biocide. It is also probable that they would be useful in protecting the natural environment from the movement of contaminated water, sediments and leaf litter to it. During site inspection around the South George River no buffer zones were evident. Healthy, young plantation trees were growing adjacent to the banks of the river. There was no apparent protection to the streams from the movement of contaminated water, sediment or contaminated organic matter.
During this site inspection large amounts of foam was accumulating in the South George River. The entire visible area upstream was blue gum plantations. This foam was initially believed to be a dispersant/detergent, used to make water insoluble chemicals disperse in the helicopter tanks, so they can be sprayed. A sample of this foam was taken."
It was found to be the result of contamination by animal tissue.
"The potential implications of having contamination of the river from dead animal tissue needs to be considered."
The Forestry Practices Code 2000 provides details regarding the expected size of buffer zones adjacent to areas of clear felling and plantation operations. Watercourse protection is outlined in section D2.1 on page 55. It states, "Native vegetation will be retained intact in Class 1, 2 and 3 streamside reserves as defined in Table 8 below, subject to other provisions in this Code permitting watercourse crossings and selective harvesting under certain conditions."
Reference: 'Environmental Problems Georges Bay, Tasmania'. Collated by Dr Marcus Scammell from information gathered, in particular, between February 2004 to June 2004. Information gathered by: St Helen’s Marine Farmers; Dr Alison Bleaney (Area Medical Officer); Dr Marcus Scammell (Marine Ecologist)