Marty Sharpe, writing in the DomPost a few days ago, came up with some interesting maths regarding a potential diary cow invasion of Central Hawke’s Bay.
Presumably to help build a case for more transport funding, the newly adopted Regional Land Transport Strategy prepared by the Regional Council projected the possibility of as much as 1,720,000 litres of milk being produced and trucked over the region’s roads. As the HBRC Strategy describes, this would be the outcome if 40,000 hectares of land, irrigated by the proposed Ruataniwha water storage scheme (i.e., CHB dam), were converted entirely to dairying.
Now, for the record, the HBRC has been insisting to folks that only ‘some’ of the newly irrigated hectares would probably go to dairying. An often floated number is ‘maybe one-third’. HBRC has prepared a series of potential land use scenarios in order to estimate both production value and pollution impacts of the scheme. but they have not yet shared these with the public.
Marty used Dairy New Zealand figures for milk production to calculate CHB would require 106,500 dairy cows to produce 1,720,000 litres of milk per day. That would generate quite a heap of cow effluent dumped into our environment.
I’ll add some more math to improve your sense of the impact. One cow produces the same amount of ‘effluent’ as fourteen people, according to a report prepared for the Ministry for the Environment.
So, 106,500 cows translates into 1,491,000 people. That’s quite a daily flush!
OK, let’s pare back the numbers to something more likely (although no one can be sure what CHB’s farmers will do with more water).
Assume only 30,000 hectares irrigated, not 40,000. And only one-third of those into dairying.
That brings the dairying hectares down to ‘only’ 10,000. A bit more than double the land now devoted to dairying in CHB.
Reducing the litres of milk to 430,000 per day.
Bringing the number of dairy cows required down to 26,625.
Or only 372,750 people flushing into the Tukituki catchment.
I’ll bet you can’t wait to see that ‘land use intensification mitigation plan’ the HBRC is working up!