He said various areas of the site have differing infiltration rates, this being related to compaction of the soil in some parts when the border dykes were built.
Work on de-compacting and improving soil structure was done this year by incorporating organic matter into the soil "with good results".
"This work will continue in specific locations over the site to continually improve the irrigation operation."
Mr Hopman dismissed claims that there had ever been an overflowing of wastewater into Makora Stream.
He said a higher than expected water table near the old pond 2 and pond 3 meant that area could not be used for irrigation.
"Options being investigated for this area include a wetland."
Responding to claims by scheme watchdog and district councillor David Holmes that the quality of baleage cut from the land was poor, Mr Hopman said in fact the quality was "excellent".
"Only 3 per cent was classed as seconds. All this year's bales were sold and half next year's production has already been pre-sold.
"Feedback regarding quality from customers has been very positive and test results are consistently good," he said.
Irrigation over summer had resulted in a greater loss of nitrogen from the soil than had been expected.
This had caused some yellowing of grass and urea will be added in the spring to bring nitrogen levels up to the target range before the next baleage harvest.
The irrigation areas already constructed will always be used as the primary location for the disposal of treated effluent.
"However, the council is committed to further reductions in discharges to the river and has made provision in the Long-Term Plan for additional irrigation options in year 2 ($1.5m) and $37m in 19 years' time.
"These options may include distribution to farmers and to assist in evaluating the feasibility of this, the council has undertaken trials at Homebush to produce Fonterra standard water for potential use on dairy farms," Mr Hopman said.
He said the forecast cost for the ongoing Homebush operation is contained in the Long-Term Plan as is its impact on council expenditure for the next 30 years.
"We expect the Natural Resources Plan will require us to further reduce treated wastewater discharged into the river. The most likely scenario, and timing of this, will be subject to further consultation with Iwi, GWRC and the community," Mr Hopman said.
Options for increasing treatment capacity to further reduce the need to discharge treated effluent into the river include:
-wetlands
-further treatment of effluent to Fonterra standards for use on dairy farms
-building further irrigation areas on council-owned land
-a reticulation system for treated effluent for irrigators to use
-extra pond capacity for the storage of winter flows.
A budget provision of $1.5 million has been allowed to implement the selected option/s.
