Farm Dairy Effluent Treatment in the Waikato Region
Since the Waikato Regional Council changed the rules governing farm dairy effluent treatment in 1994, many farmers have installed land-based treatment systems. Irene Parminter addresses two issues raised by this management change: Why have farmers converted to land-based disposal in such large numbers? And what has been the environmental effect of the change?
The Waikato Regional Council (Environment Waikato) changed and standardised the rules governing the disposal of farm dairy effluent in the region in order to improve surface water quality, protect ground water quality, and take heed of Maori cultural concerns. The rule change made the application of farm dairy effluent to land a permitted activity under the RMA (i.e., no consent is needed, and no annual fees are payable), provided certain conditions are met. The Regional Council also mounted an education campaign promoting the benefits of land-based treatment.
Before the rule change, most Waikato dairy farmers treated farm dairy effluent using two-pond or barrier ditch systems, that discharged treated waste to waterways. While pond and ditch treatment is reasonably effective at reducing nutrient and suspended solid levels in effluent, the number and volume of discharges had begun to overwhelm the assimilative capacity of the region’s waterways. Recent Environment Waikato research into the discharge from 140 pond systems in the Waikato found that the effluent contains, on average, 220 g/m3 of suspended solids, 91 g/m3 total Kjeldahl nitrogen, 20 g/m3 total phosphate and 35,000 faecal coliforms/m3.
The impact of the rule change and education campaign on treatment methods was dramatic. Between 1993-94 and 1996-97 the proportion of farmers using land-based treatment increased from 39 percent to 63 percent with a corresponding decline in the number of discharges of treated (and untreated) farm dairy effluent to water.
The financial incentive for such a change is weak. Farmers installing and using land-based treatment systems face higher capital and operating costs than farmers installing pond or ditch systems, but gain benefits from the nutrient content of the effluent, and save consent costs. On an annual basis, the fertiliser benefits are likely to exceed the operating costs of a land-based system on an average Waikato farm. However, on an average-sized farm with an existing pond or ditch system, the investment in a land-based treatment system has a low Internal Rate of Return (less than 4 percent), given average management of the system. This suggests that non-monetary incentives may be a strong factor in the decision to install land-based treatment. For large dairy farms converted from drystock, the investment in land-based treatment systems is likely to be more profitable (with an Internal Rate of Return of more than 8 percent), due to economies of scale, and the saved costs of building a pond/ditch system.
A reduction in point source effluent discharges to streams and rivers of the magnitude implied by the shift in treatment methods described, could reasonably be expected to result in a measurable improvement in water quality in the region's waterways. However research to date by Environment Waikato has provided no overall pattern of water quality improvement in the region over the period. Although some waterways in dairying catchments have shown significant reductions in nutrient levels, others have shown significant increases. The reason for this ambiguous result is not clear, but is likely to be related to a number of issues, e.g., intensification of land use in the region; the relative importance of farm dairy effluent and other discharges (including non-point sources); application rates and management of land-based systems; and management of the remaining pond and ditch systems.
The size of the investment made by farmers in land-based systems in the Waikato, and the cost to farmers of altering the rules, suggest a need for greater understanding of the relationship between treatment systems and water quality before the rules are adjusted significantly. In hindsight, when the rule change was made it would have been useful to mount a water quality monitoring campaign in selected catchments where pond/ditch treatment systems predominated, in order to clarify the impact of changes in treatment methods.
From a policy viewpoint, the Waikato experience illustrates the magnitude of voluntary change that can be effected by the combination of a low-key economic instrument (in this case, making land-based treatment a permitted activity, saving the farmer consent application and annual fees) and a focused education campaign.
The Waikato experience also illustrates the importance of having an understanding of the relationship between the environmental outcomes sought, the behaviours that could be targeted to achieve those outcomes, and their costs, when developing policy. A monitoring programme to relate changes in behaviour to the environmental outcomes achieved, is also a beneficial component of the policy process.
 |
Irene Parminter Senior Policy Analyst, Hamilton. Irene has worked for MAF for the past three years. Her background is in horticultural and environmental economics. Recent work has included analysis of roading reform, telecommunications, and effluent disposal, as well as an ongoing role in horticultural monitoring and forecasting. |
Contact for Enquiries
Amber Duncalfe
Editor - RM Update
Ministry of Agriculture and Forestry
PO Box 2526
Wellington
NEW ZEALAND
Tel: +64 4 894 0710
Fax: +64 4 894 0745
Contact this person
