So far 630 plans have been done, half of them on erosion-prone parts of the region. If progress continues at the present rate there will be 27 per cent less sediment overall in rivers by 2043 - 50 per cent less in some. The plans cover 60,000ha of the region's most erosion-prone hill country.
Some of the most at-risk land is in the Whangaehu and Turakina valleys. Those rivers are on track for a 30 per cent reduction in sediment. The middle and upper Whanganui River and Kai Iwi Stream are also high priority.
As well as a push for more implementation of plans, there is also a push for implementation on the most erosion-prone land. It makes a big difference - 13 per cent of the region's farmed hill country is contributing 50 per cent of sediment loss.
SLUI has been a voluntary scheme, and Mr Roygard said that was key to its success.
At first farmers were slow to take it up, but they were queuing later. There are about 150 at-risk farms in the region whose owners have never wanted a plan done. Horizons continues to contact them, in case they change their minds.
"We would always welcome any of those farmers coming on board."
But Mr Roygard said the council had plenty to do without them.
It has considered charging for the plans, but has so far decided not to. Charging could put people off having a plan done.
On the other hand news that charging is being considered could motivate landowners to get a plan done while they are free. And people who pay for plans could be keener to action them.
Farmers have to pay for some of the actions recommended. Horizons can help them get forestry funding through the Afforestation Grant Scheme. About half of its grants last year were for manuka, harvested by bees to make honey.
"We have a lot of interest from farmers within SLUI about manuka - either planting or allowing land to revert. Manuka will still provide an environmental benefit, though it's slower than a forest."
Other grants are available, with 70 per cent of costs paid on the most erosion-prone land, and 30 per cent on less fragile country.
Climate change is a wild card in the SLUI mix, and Horizons staff will consider whether it means new methods are needed.
If the most extreme climate change happens the effect of all the SLUI work will be to reduce sediment by 5 to 10 per cent, rather than the 27 per cent first predicted.
Mr Roygard said the situation would be worse if the SLUI was abandoned.
"If we don't keep the programme operating at the pace that it is, there's potential for erosion to increase and water quality to decrease."