Tomorrow sees us officially commence irrigation season and it will also see the issue of the season’s first Water Shortage Direction from Environment Canterbury based upon unanimous advice from Opihi Environmental Flow Release Advisory Group (OEFRAG). The advice given from OEFRAG was to reduce the minimum flow at the Sale Yard Bridge (SYB) flow monitoring site from 6m3 to 5.2m3 for a two week period, commencing 1st Sep 18. In conjunction with this, water permit holders affiliated to the Opuha dam reduce their water takes to 75% of their consented volume.
OEFRAG has met recently to consider the less than desirable water and snow conditions. Presently the lake is at 90% capacity, Lake Inflows are below the historical 25th percentile, as of today the 7 day moving average inflow is only 2.6m3, and the snow pack for our catchment is close to the 10th percentile (for comparison it is close to 33% less snow pack than the 2014/15 season presently). The rain gauge at the dam has only recorded 42.5mm of rain since 1st June this year.
These early months of the irrigation season are the ones where river restrictions are more amenable due to the higher minimum flows. The peak summer months have lower minimum flows and therefore there is much less ability to make any meaningful impact to intra-season water storage, as the 2014/15 season demonstrated.
The drought of 2014/15 clearly demonstrated to us that early intervention is needed. We acted too late in 2014, not putting restriction on until 1st December. We want to do everything in our power to ensure the 2018/19 season is not a repeat of 2014/15 which saw an empty lake, very low river flows and a cease to all irrigation
We are watching the weather forecasts presently available with some interest. It looks like there is potential for some meaningful rain early next week.
This WSD direction is valid for a two week period at which point further assessment will take place to determine the most appropriate river management scenario going forward.
If you have any questions on this matter please get in contact with Andrew Mockford, CEO – phone 021 333 043 or email andrew@opuha.co.nz.
