4. Modelling the Status Quo and the Proposed NES

The modelling of the timing of the uptake of measuring devices has been derived from the water allocation consent database prepared for the Ministry for the Environment by Aqualinc (2006a, 2006b, 2006c). This database describes all consented water takes in terms of take rate, annual allocation, outlet type, primary use, consent expiry date, etc. The database does not, however, describe whether or not an individual consent is the subject of measurement. This is achieved through analysis “of the number of consents without measuring devices and assumes that the current distribution of metered consents is similar to the distribution of take rates” (Aqualinc, 2006b). The consents database provided by the Ministry has allowed for the modelling of the uptake of water-measuring devices by region, take rate and consent expiry date.

4.1 Modelling the status quo

Many regional councils already require that new water consents be measured and that existing consents be measured upon replacement. Modelling of the status quo assumes that water-measuring devices will be installed upon consent replacement and, in the case of Canterbury, under consent review processes and the implementation of an operative Natural Resources Regional Plan. There will, however, be exemptions, generally associated with smaller take rates. The modelling of specific exemptions has created the need to make some assumptions regarding take rates that are likely to be exempted under the status quo. Table 17 details these assumptions.

The status quo results in some 10,300 water-measuring devices being installed over a 36-year period. This value includes those installed within the timeframe of the proposed NES, either voluntarily or under consent review processes and at consent replacement. Voluntary uptake of measuring devices includes the installation of measuring devices under consent review processes (outside of consent replacement) and is likely to result in a significant number of measuring devices being installed under the status quo but within the proposed timeframe of the NES. An example of this is the likelihood that some 600 consents in the Rakaia−Selwyn District that are the subject of a consent review process will be required to have measuring devices installed. We have assumed that 25 percent of existing unmeasured takes, over and above those required at consent replacement, would instal measurement devices within the proposed timeframe of the NES, which is consistent with the assumption made in the preliminary cost−benefit analysis (Ministry for the Environment, 2006). This assumption appears reasonable given current initiatives by various regional councils (ECan, Hawkes’ Bay Regional Council, etc.).

Under the status quo, some 2,500 (13 percent) consented water takes will remain unmeasured at the end of the 36-year period. These primarily relate to take rates of less than 5 L/s. This figure also includes 432 consents associated with the West Coast Regional Council.

Table 17: Status quo model assumptions – uptake of measuring devices

4.2 Modelling the proposed NES

Under the proposed NES all consented water takes will be required to measure actual water take within five years of the regulation being gazetted. Because the NES specifies standards for measuring devices, it affects some consents that are currently measured as well as those that are not currently measured.

Consents that are currently measured

In modelling the uptake of water-measuring devices it needs to be recognised that a proportion of existing devices will not meet the standards of the proposed NES. Currently measured devices include those that have been installed:

• under an existing consent, where the consent conditions exceed those of the NES

• either voluntarily or under consent conditions that do not meet the NES.

Where existing installed measuring devices are subject to consent conditions that are equal to or better than those given in the proposed standard, it has been assumed that they will meet the requirements of the NES. It is likely that some will not, but this becomes a compliance issue associated with the council. That is, if they do not comply with their consent condition, they are also unlikely to comply with the NES, and therefore the proposed standard does not add any additional cost to that already imposed by consent conditions.

Water-measuring devices that have been voluntarily installed or installed under consent conditions less rigorous than the NES may not meet the conditions of the NES. Key reasons for non-compliance include:⁴¹

• an inability to meet the ± 5% accuracy standard due to wear and tear on mechanical meters

• the installation does not meet the manufacturer’s specifications.

Mechanical meters installed more than four to five years ago are unlikely to meet the accuracy standard, due to wear and tear. These meters would require either complete replacement or replacement of the mechanical register. Mechanical meters are particularly vulnerable to wear and tear when used to monitor surface-water takes, or when water has high silt content, or where there are elevated levels of magnesium and iron. Instances where a meter installation fails to meet the manufacturers’ specification are likely to be confined to those installed more than five years ago.

Little is known about the extent to which currently installed measuring devices meet the proposed standard. We have assumed that 20 percent of existing water-measuring devices would not meet the proposed standard and would require replacement. This is consistent with the assumption employed in the preliminary cost−benefit analysis reported by the Ministry for the Environment (2006). This assumption is tested via sensitivity analysis.

Unmeasured consents

The analysis assumes that all unmeasured consents have compliant water-measuring devices installed over a five-year period.

4.3 Summary

The status quo results in some 10,300 water-measuring devices being installed over a 36-year period. The proposed NES results in approximately 14,200 water-measuring devices being installed over a five-year period subsequent to the gazetting of the regulation. This assumes that 20 percent of existing measuring devices do not meet the standard and that the proposed NES results in all unmeasured takes possessing measuring devices within five years of gazetting the regulation.

Figure 4 illustrates the uptake of water-measuring devices under the status quo and the proposed NES scenario. The increase in the uptake (year 10 to year 15) of measuring devices under the status quo results from ECan’s proposed NRRP becoming operative within five to six years and measuring devices being installed over the following five to ten years.