The late Bill Benfield
Is Fencing Rivers a Failure?
by John McNab
The late Bill Benfield, an outstanding and fearless Wairarapa conservationist, wrote two outstanding books on the “pest and poison” issue mainly around 1080 poison. They were “The Third Wave” and “At War with Nature”, both published by Tross Publishing. Buy them direct from Tross Publishing or from Paper Plus. Bill wrote a very good third book “ Water quality and Ownership” in which he questioned the value of fencing riparian strips along rivers and streams.
He described “the fad of fencing rivers has been a ‘knee jerk’ response to Fish and Games’ accusations of “dirty dairying".
Bill Benfield said the policy of riparian strips was well intentioned but failed to fully address the problem of nitrate run-off and leaching.
“Logically the problem is one of the total catchment, i.e. watershed management, not just a five or ten metre strips alongside streams,” he wrote.
Bill Benfield said there other factors that could be damaging to river and stream ecology of which after all, trout were part of.
One was the widespread use of damaging chemicals such as diazinon, DDT’s replacement, for combating grass grub. It was ratted as “a clear threat to aquatic ecosystems.” Also the silt and debris-laden run-off from clear-felled commercial radiata plantations was another.
“Fencing off streams was more a public relations reaction. As an added public sweetener, the fenced off river margins were planted with natives. But then you’ve got no access through the hedge of blackberry, willows and other vegetation,” he added.
From an anglers’ viewpoint, riparian strips quickly became overgrown with weeds like blackberry, broom, gorse and even the poisonous tutu. The river becomes inaccessible for trout fishing while doing nothing to stop most pollution from entering the waterways.
What was needed was a more focused system of river management. Where there was no intensive dairying, river banks could be managed in a natural unfenced condition.
“Stock, like sheep, goats and horses are not a major problem with minimal impact on banks and well within the healthy life of the river, with its cycles of high and low flows. Cattle can be a different issue; it is an issue of density and a matter of finding a reasonable level at which agriculture can co-exist with the river,” said Bill Benfield.
Where cattle densities were high and stock received supplementary feed, they should be excluded from the river. If mixed stock are grazed, i.e. sheep and cattle, then the “selecta-fence” can be the answer – two top wires to stop cattle and no bottom wires to let sheep through.
“As an example of corporate posturing, fencing rivers has been a stunning success. As a solution it has been a failure,” he said.
While it is likely that on certain rivers fencing does cause issues, on others it's a godsend, for instance a tussock lined stream I know has been fenced now for a number of years, there's a lot more riparian vegetation providing habitat for trout food, the stream is 'more natural' looking, as nature intended, there is a little broom and gorse, which DOC manages. Suggest it is more a case of managing each stream depending on it's type to ensure a good outcome, certainly a one fit for all is likely not to work.