Aquifer tests throw doubt on water availability
October 21, 2008
Aquifer tests throw doubt on water availability.
Environment Canterbury (ECan) has received preliminary results from the leakage tests required under the commissioner’s decision to grant groundwater consents in the Selwyn-Rakaia groundwater zone.
One of the critical factual issues that influenced the commissioner’s decision in March 2008 was how further extraction of water from aquifers at depth would affect levels in the upper aquifers. The levels in the upper aquifers govern stream flows in the spring-fed lowland streams.
“The leakage tests were part of the conditions placed on applicants to test the impact of taking water at depth. While the results from the first tests are preliminary, they all show signs of significant leakage. This is consistent with the advice that ECan scientists presented to the hearings panel,” says ECan chief executive Dr Bryan Jenkins.
“As the hydrogeology of the Selwyn-Rakaia is similar to the Selwyn-Waimakariri and other groundwater zones in the Canterbury Plains, these results are likely to have wider ramifications.”
The Selwyn-Waimakariri decision also requires consent holders to reduce the effects of their water take to a minimal level or cease pumping.
The commissioners in the Selwyn-Waimakariri case made it clear that the purpose of the tests is to confirm advice they received from applicants and their advisors and that the applicants are aware of the risks they are taking.
In the report, the commissioners stated that “all we can do is to provide a mechanism that allows the consent holder to complete their investigations and evaluations and allow them to take water if those investigations and evaluations show that effects on the environment and on existing users will be less than minor as proposed by their consultants. However, we make it plain that we clearly understood the applicants understand the risks they are taking.” (See paragraph 996, Selwyn-Waimakariri Groundwater Decision. www.ecan.govt.nz/hearingdecisions)