From the Executive summary

...This report contains a high-level analysis of the likely economic costs and benefits associated with two proposed investment options relating to Auckland Council’s Natural Environment Targeted Rate for the 2018-2028 Long-term Plan (LTP). Expenditure on the natural environment in the LTP is based on planned activities that will occur according to the Regional Pest Management Plan which has eight outcome/investment areas. These include expenditure in both terrestrial and marine environments. In addition the LTP includes investment in marine ecology and the Pest Free Auckland initiative. ...

Cost Benefit Analysis results

For a programme or planned expenditure to be considered worthwhile, it should have a Net Present Value (NPV) greater than zero, and a Benefit to Cost Ratio (BCR) greater than 1.

The range of estimated net benefits (i.e., the extent to which society is better off because of the options) are 2017$293.2 million and 2017$734.2 million in present value terms for Option A and B, respectively, with a corresponding BCR of 1.08 and 2.80. Both Option A and B have a positive NPV for the base or Medium scenario, indicating that the cost of any investment is offset by the benefits resulting from that investment.

It is important to note that these results do not include the benefits that were not measured due to data/information constraints. Our assessment is that the effect of including such impacts would be to raise the net benefits significantly.

It is not envisaged that the analysis is missing cost estimates (due to lack of data): the CBA is an analysis of likely outcomes due to the level of spending identified in the two Options. ...

Conclusion

While the study is exploratory and indicative in nature, it supports the view that society is likely to be better off from both the Natural Environment Investment Options for the LTP.

A conservative approach to measuring the benefits was adopted at all times. There are benefits that were not quantifiable, and hence not included in the analysis. Option B is the preferred option as it has much higher benefit to cost ratio and society would be better off even under the Lower bound scenario.

As is common in exploratory studies of this nature, the precision with which estimates of costs and benefits can be made could increase with further, more detailed work.

Auckland Council technical report, TR2018/005