Effluent management in the Northern Irrigation Region
Note Number: AG1040
Published: October 2002
Updated: July 2009
The Northern Irrigation region boasts a highly productive and adaptive dairy industry. With continued uncertainty in seasonal irrigation allocations, farming practices have adopted a more intensive approach with more supplementary feeds being imported into the farm. The establishment of feedpads and other feeding facilities has enabled the industry to maintain production.
With 98% of dairy farms utilising surface irrigation practises, there are many opportunities for farmers to develop an efficient effluent management system maximising the nutrient content of dairy effluent to increase pasture and soil productivity.
Dryland farms which do not have this opportunity to utilise surface irrigation are often limited in the areas in which effluent can be applied and therefore must implement other options such as travelling irrigators, slurry injection, spraying applications or slurry spreading.
Typical effluent systems
Farmers operating in the Goulburn-Murray Irrigation District have the necessary skill and knowledge to irrigate pastures; therefore shandying effluent into the irrigation cycle should not be a daunting task.
Due to the flatness of irrigation land in this region most farmers traditionally opted for a single turkey nest effluent storage with 65% of farmers pumping into the pond from a sump or solid trap at the dairy. The effluent can then be gravity fed into the irrigation system (farm channel), thus avoiding an additional pumping application.
However, over recent years with dairy farms becoming more intensive with the introduction of feedpads, dual or multiple pond systems have been implemented to service the higher water requirements of floodwash and hydrant wash-down systems.
The recycling option from second ponds has provided a secure water source, in particular during seasons of lower water allocations.
The Introduction of Feedpads
With a significant shift towards intensive farming practices and the introduction of more permanent feeding facilities such as feedpads and designated feed-out areas the need to review effluent management practices on the farm is paramount. It is a dangerous assumption to assume the existing effluent system design for the dairy shed is sufficient to cope with the development of feedpads, in particularly the concreted floodwashed systems.
All new developments on the farm that concentrated the dairy herd should consider how effluent will be collected and managed.
It is important to understand, that it is not the herd size that determines pond sizing, but more specifically the amount of water generated in the milking process and the amount of time the herd spends on holding yards. This includes, water utilised in vat washing, plant rinse, pit and platform washing, cup spraying, teat spraying and yard washing. A further calculation, which is often underestimated, is the volume of rainfall running off shedding and yarding areas, which may enter the effluent stream. Unless these areas have rainwater diversions they also will add to the ponds size.
The storage requirement in the Northern Irrigation Region has traditionally been 123 days (1 st May – 31 st August), which is the period when irrigation water is unavailable and pastures are generally too wet to apply dairy effluent.
Therefore to reduce unnecessary large effluent storage farmers should critically evaluate the water utilisation in the dairy shed. For example, recycling plate cooler water, determining actual flood washing requirements and installing rainwater diversions will significantly reduce water consumption, hence pond size.
The preparation of a whole farm plan is recommended before installing new or altering existing effluent systems. These plans are a valuable resource to landowners and are readily available throughout the region.
This enables the most appropriate site to be selected utilising the farms individual layout and will ensure the effluent system is incorporated into other areas such as irrigation and pasture development.
Ideally effluent ponds should be located next to farm irrigation channels close to the water wheel to allow effluent to be shandied into fresh water and distributed over a large area of the farm.
Groundwater can be close to the surface in the irrigation region, which restricts pond depth. Effluent ponds must be 0.5m above the water table and constructed of clay to prevent effluent seeping into groundwater. Pond lining is another option that may be explored.
Conveyance of Effluent Around Channels and Drainage Structures
As is common in most irrigation regions the need to strategically layout effluent piping under and around channels and drains is a given, that requires carefully planning and consideration.
Dairy effluent has the potential to have a detrimental effect on the environment if it is poorly managed and allowed to enter waterways and drainage systems. The nutrient loading in dairy effluent has the potential to severely reduce water quality and increase the likelihood of blue-green algae blooms.
Due to the high risk of piping dairy effluent across irrigation channels and drainage structures it is the recommendation of Goulburn Murray Water (GMW) and the Department of Environment and Primary Industries (DEPI) that pipes conveying effluent be located under these structures to the specified guidelines.
Effluent pipes must be cased in the approved pipe and bored under G-MW channels and drains to the approved specifications and standards set by G-MW. Fees and security deposits must be paid and appropriate licences and permits obtained prior to installation.
No pipe joiners are to be used in the section of pipeline located under G-MW reserve or easement.
Farmers with an intention to under bore must notify G-MW.
Requirements of Local Shires
The shires of Campaspe, Moira and the City of Greater Shepparton introduced planning controls for earthworks in 1994. These controls require that you consult your local council before undertaking any earthworks.
These controls are concerned with any earthworks which:
- Alter the direction or rate of water flow across a property boundary.
- Change point of water discharge from the property or
- Increase the discharge of saline groundwater.
Farmers building new dairies or altering existing sheds, should upgrade their effluent system, to ensure any changes in either herd size or water use in the dairy is compatible with the current effluent system.
For example, the installation of a floodwash tank or hydrant system to wash the dairy yard will significantly increase water use at the dairy. Therefore current storage will need to be altered accordingly.
It is a requirement for certain shires in the Northern Irrigation region to request an effluent management plan before issuing permits, especially for new dairy developments.
Regulatory Auditing of Effluent Management
In 2006 the Environment Protection Authority extended its effluent-auditing program into the Northern Irrigation region following four years of auditing in the southern catchments.
The audits indicated that overall effluent management on farms had deteriorated with a shift in priorities due to drought and industry limitations.
A key finding from the audits highlighted that even well constructed effluent systems posed risks to the environment, if not probably management and maintained.
It is likely that, the regulatory auditing programs for effluent management will continue in the near future.
Farmers wishing to implement Effluent Management Plans specifically tailored to their farm should contact an appropriately trained service provider. This list of service providers may be obtained by contacting the following DEPI Offices.
- Echuca (03) 5482 1922
- Warrnambool (03) 5561 9946
This Agnote was developed by Scott McDonald, October 2002.
It was reviewed by Scott McDonald, Farm Services Victoria. July 2009.
Published and Authorised by:
Department of Environment and Primary Industries
1 Spring Street
This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968.
The advice provided in this publication is intended as a source of information only. Always read the label before using any of the products mentioned. The State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication