Saving Our Streams

Forest and Bird, Issue 303, 1 February 2002, Page 28

Saving Our

Streams

ANN GRAEME

finds fencing riverbanks

is good for farming and wildlife.

he cow clambers down the bank, her hooves dislodging a shower of earth. Dirt falls into the stream. She stands in the cool water, drinking. Then she lifts her tail. Faeces, urine and dirt swirl down the stream together. There goes a cocktail of eroded soil — precious topsoil — along with digested grass, pathogenic bacteria, protozoans such as giardia and cryptosporidium, nitrogen and minerals. Every moment, every day, this scene is repeated throughout rural New Zealand. It has been so since farming began, but now it is happening more than ever before. For dairy farming is booming. Where a few sheep and cattle once grazed, now hundreds of dairy cows eat

and eat, processing grass into milk as well as meat and creating the effluent equivalent to millions of people. And without buffers around the streams, some of that effluent gets into the streams and so does some of the fertiliser, liberally spread to increase meat and milk production. Erosion and run-off are natural phenomena. Indeed, they are part of the natural food chain that stream life is adapted to deal with. In the cool, oxygenrich water of a shady bush stream, bacteria take in the organic waste and algae growing on the rocks use the minerals. On the algae and decaying matter feed mayfly and caddis larvae and a host of other invertebrates. They, in turn, are eaten by fish and birds. But gross enrichment overloads this cycle, creating choking pollution. Too much erosion smothers the stream bed

with silt which is carried downstream to degrade the harbour. This is our topsoil and our fertiliser, washing out to sea. Too much organic matter like faeces needs too many bacteria to ingest it and the bacteria use so much oxygen that the water becomes depleted. It becomes cloudy and smelly and anaerobic bacteria thrive. Deprived of oxygen, the mayfly and caddis larvae die, and so do the fish. And as the streams through the paddocks have no shade, the water warms and this hastens the depletion of oxygen. This runaway pollution has many serious consequences. It threatens the health of the people and the stock who drink it. It wastes topsoil and fertiliser. Significantly, it destroys the stream habitat and natural river life. For all these reasons, we should be concerned to protect our streams.

Protecting streams O protect streams and native wildlife from the excesses of agriculture, the first prerequisite is to fence the stream edges so stock cannot get into the water. Once fenced, even weed-infested riparian margins go a long way to control erosion and run-off from the paddock. Better still are tree-planted margins which shade and cool the stream water and provide habitat for birds and insects. Admittedly, fencing is expensive, both in manpower and in money, yet many regional councils now offer subsidies for riparian fencing, and for streamside planting of native trees, and for piping water to troughs. There are also encouraging signs that some farmers are conscious of the dangers farming poses to unprotected streams and are doing something about it. As these case studies show, the result is creating improved habitat for nature and better farm management.

ANN GRAEME is the organiser of Forest and Bird’s Kiwi Conservation Club.

On the flanks of the Kaimai ranges near Katikati in the Bay of Plenty, Rick Burke farms sheep and cattle on his property and on the adjacent farm of his father-in-law, Derry Seddon. Through their land runs the Manaia Stream, flowing from its source in the Kaimai Conservation Park down to the Tauranga harbour. Bit by bit, over 10 years, Rick and Derry have fenced and planted nine kilometres of stream bank. Environment Bay of Plenty, which has provided funds towards the fencing and planting, has taken a keen interest in the stream’s restoration, monitoring the water quality and the life in the stream. The number of native fish has increased, with now five times as many banded kokopu as previously. The farm has benefited too. ‘Fencing the stream has been the key to better land management,’ says Rick. ‘It has given us a fixed boundary to fence off and smaller paddocks. Smaller paddocks give better stock management and land use.’ ‘But what about the weeds that will surely invade the fenced stream banks?’ ‘We’re fencing the weeds in,’ says Rick. ‘With the tighter grazing the riparian fence allows, the weeds don’t establish in the pasture. They’re no problem and the trees and rank grass eventually get on top of them.’ Stock in streams isn’t just bad for the streams; it’s bad for the stock too. They have accidents. Rick had lost stock over bluffs and in the stream. And stream water can carry diseases like liver flukes. Cattle and sheep like clean water. When a water trough is provided, they drink from it in preference to the muddy creek. In remote hill country where fencing is impractical, clean water in carefully placed troughs will help lure stock away and reduce the pollution of unfenced streams. Rick sees riparian fencing as the farmer’s tool. Beyond these practical considerations, however, he also enjoys the clear waters of the Manaia stream. Framed by trees and meandering through the paddocks, the stream makes his farm a beautiful place.

The Benefits of Fencing Streams

To the farmer: e higher production e better paddock utilisation from ‘break’ feeding e healthier stock @ easier management e fewer stock accidents.

To the stream and nature: e less sediment and nutrients e clean water e more diverse stream biota e safe spawning places for fish.

Twelve years ago, Jos Van Loon came from Holland to farm dairy cows at Waotu in the South Waikato. An innovative and thoughtful

farmer, Jos runs a high quality and highly productive farm milking 450 cows. The Little Waipa stream runs across his farm and the previous owner had fenced it. When a flood damaged the fences, Jos pulled them out. He saw no need to waste that grassy stream margin which the cows could eat. But a few years later Jos fenced the stream again, and this time he made the riparian margin much wider, up on the banks beyond flood level. Inside the fence he planted native trees and flaxes, not too densely so borders of long grass remain which capture soil, nitrogen and phosphates washing from the paddocks. This is helping to lessen the sediment which the Waipa River carries, an annual load which equates to between 30 and 90 tonnes for every square kilometre of its catchment. That’s a lot of lost soil, but it’s not coming from Jos’s farm. Now Jos runs the local stream-care group, helping other farmers protect their waterways. And what caused this change of heart? Says Jos, his English still tinged with a Dutch accent, ‘Sustainability is more important than the last dollar. We boogered up Holland. We mustn’t boogger up New Zealand!’