Here are some of our findings
1. Finniss River Ford (FRF). This has been consistently above pH 7.
15/5/09, pH 7.4
2. Finniss River - Wally’s Landing (WL), an anabranch of the Finniss River
The River has been consistently above pH 7.
From this we have concluded that the ASS in the river banks is not entering the river. The CSIRO has recommended further monitoring in order to better understand the connectivity. It appears that the river would need to flood or that rain would need to saturate the banks for the existing acid to be mobilised. Our testing has shown the presence of calcium carbonates that are helping to keep the pH high, where we would like it to stay. Once again we will need to monitor to learn of the buffering capacity of the banks.
14/5/09 - We took readings along a line beginning with the bank of the upstream jetty down to the water and then on the other side of the river. We called this site WL1.
pH 6.7: WL 1a - 5 m. from bank
pH 7.0: WL 1b - 8 m. from bank
pH 7.1: WL 1c – 10 m. from bank
pH 7.7: WL 1d – in river
Other side of river in same line
pH 6.1: WL2d - 4 m. from water’s edge
pH 5.5: WL2e– a little further downstream
pH 3.3: WL2f – in bank in cow foot print – this is low and a concern but is currently not mobilised.
3. Finniss Pools and newly rewet creek (BW)
We took readings in the creek that flows through three pools and into an anabranch of the Finniss River below Wally’s Landing (BW). This is an area that has rewet with recent rains and there is acid in the creek and banks and wetland through which the creek meanders.
pH 3.9: BW 1a -10 m. above cascade between the lower pools.
pH 5.5 in lower pool. We expect to find a very low pH in the banks of the lowest pool, probably below 2.
As we walked up the creek we found that the readings (pH 4.5) in the cracks along the banks were higher than in the water (pH 3.9). This is the reverse of what one might expect. One hypothesis is that the acid that has formed in the cracked clay that had dried over summer has been mobilised by the newly running creek and is being transmitted through sand below the surface clay. As we walked further upstream and into the wetland, the pH rose.
We recorded pH 6.5 in isolated hole and the creek pH 8.2 and 7.3 in wetland above where the creek was running We saw the prints of kangaroo and ibis. We found mussel shells and an old post and rail fence. This area has been dry before.
4. Lime site (L1)
We understand that five tonnes of lime from Lake Hawdon, near Robe is being placed in the Finniss River below Wally’s Landing on an experimental basis. We took readings above and below the lime embankment.
pH 7.5: L1- in water above bank (i.e. below entry point of acid from creek)
pH 7.1: L2 –in the bank above the lime
pH 7.5-7.6 : L3 - in crack, 30 m. below the lime
pH 8.5: L4 - in cracks below the lime
pH 9.0: L5 – in water below the lime
5. Sandy Wetland and black ooze (SW)
We walked a little way down river and into another rewetting sandy wetland. We tested the water in a pool and in the river. They were the same. pH 8.5: SW1 - in the pool and in FR. The pool was not getting benefit of upstream lime so the buffering capacity has not been exhausted. However, as with other sites, we found that readings could range widely. In a nearby hole we recorded pH 4.0 Once again we found mussels shells and a boat mooring. This area is usually under water.
22 May 2009, Currency Creek
22 May 2009
Currency Creek
CC1a, 88 metres from the bank
pH 3.2, water in pit, sandy, water bubbling through side wall at bottom of pit.
CC1b, 164 metres from the banks
pH 3.0, soil at 5 cms
ph 6.9-7.1, water is pit, black soil
CC1c, 220 metres from bank
pH 6.8 water in pit
pH 7.5 soil top layer 7.5
CC 1d, 257 metres from bank
pH 6.7 in water in pit
pH 8.00 soil in red depression
CC 1e, 276 metres from the bank
pH 4.8, 4.4, 4.8 in surface pools
oH 8- 8.5 in red depression
Management
The banks need to be kept covered: plant, mulch.
Foster bioremediation in the acidifying pools.
Address over allocation upstream, facilitate periodic wetting and drying, manage lakes at a lower level
