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Samples were collected from a central point in the middle of the dam to ensure all samples were well
mixed and that localised effects of sampling near the aquaculture operations were avoided. A sample
was also collected from the Condamine River adjacent to the farms pumping infrastructure. Both
samples were immediately frozen following collection and stored at -20°C until analyses.
Nutrient analyses were conducted on the Lachat QC8000 Flow Injection Analyser (Zellweger
Analytics Inc. Milwaukee WI 53218) following standard methods (APHA, 1995.).
3.3 Results
3.3.1 Water Harvesting and Movement
There were 11 separate water movement events from the beginning of the study period (Table 3.3.1).
These included 7 periods where water was harvested from the Condamine River and 4 from the bore
adjacent to the storage.
Table 3.3.1 Source, timing and duration of water harvesting activities at Loch Eaton from
October 2000 to February 2004
Event Source Date Started Date Finished
Duration
(days)
River pumps used
1 Bore 27/10/00 27/11/00 31 Adjacent to ring tank
2 Bore 28/12/00 11/01/01 14 Adjacent to ring tank
3 River 04/02/01 10/02/01 6 4 and 12″
4 River 14/03/01 14/04/01 31 4″
5 Bore 12/09/01 23/09/01 11 Adjacent to ring tank
6 Bore 15/11/01 22/11/01 7 Adjacent to ring tank
7 River 28/11/01 10/12/01 12 4 and 12”
8 River 26/02/03 02/03/03 4 4 and 12”
9 River 07/12/03 20/12/03 13 4 and 12”
10 River 14/01/04 28/01/04 14 4, 12 and 16″
11 River 03/02/04 15/02/04 12 4, 12 and 16″
Riverine water harvesting is an opportunistic and generally seasonal activity while pumping bore
water occurs during periods of low rainfall. The ring tank has three different sized river pumps with
diameters of 4, 12 and 16″ inches. These pumps are activated when water levels rise to a height that
permits their use. Not all of this pumping capacity was used for each of the recorded pumping events.
For riverine pumping activities lasting longer than 14 days only the 4″ pump was used. Pumping
activity lasting 14 days or less used a combination of 4, 12 and 16″ pumps. In early February 2001 a
short term pumping event lasted for six days using both the 4 and 12″ pumps. Another more prolonged
pumping event occurred one month later and lasted 31days. The last riverine pumping event occurred
in late November 2001 and lasted for 12 days. After this event, no riverine water harvesting activities
took place for over 14 months (443 days). This event was brief as water levels only permitted pumping
to occur for a total of 4 days. Late in 2003 water levels within the ring tank had fallen to less than 30
per cent of its capacity and all other storages on the farm were fully drained. As a consequence the
next three pumping events, December 2003, January 2004 and February 2004 represented a period of
significant water exchange and turnover within the ring tank. The two smaller pumps (4 and 12) were
used for 13 days during the December 2003 event while all three pumps (4, 12 and 16″) where used
for a total of 39 days in January and February 2004.
In Dalby the highest rainfalls typically occur from November through to February with December
having the highest average total monthly falls of 95 mm (AGBOM, 2005). The annual rainfall average
for the Dalby region is 676 mm (AGBOM, 2005). Despite an increased reliance on the farms
groundwater allocation during this study due to extended periods of little to no riverine pumping
activity, the majority of the farms water needs were met from riverine supplies harvested during high
flow events. Water pumped into the ring tank during these events was typical of flood waters for
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