FOMS visits Lake Frome Supergroup Springs

Image of area visited (from Keppel et al., 2016). Mulligan Springs are on the western shore of Lake Callabonna, while Public House Springs are within the Petermorra group. (The FOMS group did not visit the springs within Lake Callabonna or the Lake Blanche Springs.)

The Friends of Mound Springs (FOMS) group has a long-standing interest in the springs occurring north-east of Lyndhurst on the Moolawatana and Murnpeowie pastoral leases. These springs are described as being within the Lake Frome spring supergroup. (There are thirteen supergroups described across the Great Artesian Basin, with three of those in South Australia: Lake Frome, Lake Eyre and Dalhousie.) FOMS’ interest centres on the occurrence of significant vegetation, such as the endangered salt pipewort Eriocaulon carsonii, and the recent scientific studies that have shown that many of the springs are associated with aquifers other than the Great Artesian Basin (GAB). Historically, the springs have been described simply as GAB springs. However, recent hydrochemical studies (Keppel et al., 2016) have shown that, while Twelve Springs are apparently sourced entirely from the GAB, the other springs (Mulligan, Petermorra, Public House and Reedy) are sourced from a mixture of GAB waters and other aquifers. Four other aquifers – in addition to the GAB – are described for the area occupied by the springs.

Fairly typical landscape, the dry bed of Lake Callabonna in the background

After consulting the lessees of Moolawatana and Murnpeowie, FOMS conducted its first visit to these springs from 28 July to 3 August 2020. Planning for the trip was also assisted greatly through advice from Darren Niejalke, FOMS member and experienced springs researcher who had previously undertaken surveys of these springs. Participants on this trip were: Colin Harris, Bruce and Sherrie Gotch, Bren and Bis Lay, Brian Donaghy and Iris Iwanicki, Duncan and Caryl Ross-Watt, Bernice Cohen, Rick Moore, Stafford Dow, Chris Wenham and Simon Lewis. Duncan and Caryl made the long journey from Brisbane to be with the group.

Participants made their way by various routes to convene at Balcanoona – headquarters for the Vulkathunha-Gammon Ranges National Park – for the first night. Some bedded down in the Shearers’ Quarters while others camped nearby.

Over the ensuing four days, the group inspected a range of fascinating springs on the Moolawatana and Murnpeowie pastoral leases. There were many highlights as described below.

Mulligan Springs, 29th & 30th July

Mulligan Springs comprise a group of about thirty active spring vents on the western shores of Lake Callabonna. Nearby is the Lake Callabonna Fossil Reserve, where Diprotodon fossils were found in the late 19th century by the South Australian Museum.

The FOMS group inspected a good range of springs right on the lake shore. These included a cluster of bulrush (Typha) springs with, cumulatively, a reasonable overflow into Lake Callabonna. Not far to the south were particularly interesting mud mounds, a spring formation only recorded at one other location in South Australia (Dalhousie) and with some similarities to mud mounds near Eulo, seen by the FOMS group that travelled to Queensland in 2012. The springs were generally in good condition.

The Mulligan Springs group also includes a number of springs one or two kilometres west of Lake Callabonna, in the vicinity of old yards formerly used for mustering of horses. At least one of these springs is dominated by reeds, Phragmites – in some contrast to the Typha springs occurring closer to the lake.

Terrapinna Springs, 30th July

Terrapinna Springs

Having completed observations at Mulligan Springs, the group camped at Terrapinna Springs. Terrapinna Springs are not considered to be fed by groundwater but by surface water run-off. Associated walking trails, installed by the Walking Trails Support Group, provide spectacular views of the local area.

Twelve Springs 31st July

Utricularia fenshami flower, Twelve Springs

Twelve Springs, also on Moolawatana pastoral lease, have been of longstanding interest to FOMS because of the presence of the endangered plant, salt pipewort, Eriocaulon carsonii, that occurs in an extremely limited range of springs across the Great Artesian Basin. Also at the springs is one of the bladderworts, the recently described Utricularia fenshami, a carnivorous plant that captures small organisms by means of a bladder-like trap.

The main group of springs at Twelve Springs comprises an area of low, interconnected mounds with bore-drain sedge, Cyperus laevigatus as by far the most predominant vegetation. Eriocaulon carsonii was largely restricted to two slightly more elevated mounds where reeds (Phragmites) were growing at the main vent. There, the Eriocaulon formed dense mats in a halo immediately surrounding the Phragmites. The FOMS group also noted other more isolated springs in the immediate vicinity. Twelve Springs is recorded as having 72 spring vents. The springs were showing significant impacts from donkeys.

Following the morning inspection of Twelve Springs, the FOMS group headed north, leaving Moolawatana and entering – via the Dog Fence – Murnpeowie pastoral lease. Here the track definition to springs was a little more problematic but the group eventually located Petermorra Springs and then Public House Springs.

Petermorra Springs 31st July

Some Vegetation Comparisons between the Lake Frome Springs and Lake Eyre Springs

The vegetation of the springs bears a number of resemblances to that of the Lake Eyre springs. Bore-drain sedge, Cyperus laevigatus, is the most common wetland plant at most of the springs. Bulrush (Typha) is present at many springs at Mulligan Springs and a few springs at Reedy Springs. The common reed (Phragmites) – common at Lake Eyre springs – is more restricted: it was noted at one spring at Mulligan Springs and two springs at Twelve Springs.

There are, however, a number of distinctive vegetation features in the Lake Frome springs. As noted above, the salt pipewort, Eriocaulon carsonii, is present at Twelve, Petermorra and Public House Springs – its only other recorded natural occurrence in South Australia being in the Hermit Hill – Finniss Springs group. The occurrence of narrow-leaf wilsonia (Wilsonia backhousei) at Mulligan Springs and the nearby Lake Callabonna Springs is the only record for this species in the Lake Eyre Basin and in arid zone SA. Similarly, the bladder- wort, Utricularia fenshami, has not been recorded at springs other than Twelve Springs and Petermorra Springs.

Reference: Keppel, M, Gotch, T, Inverarity, K, Niejalke, D, & Wohling, D, 2016. A hydrogeological and ecological characterisation of springs near Lake Blanche, Lake Eyre Basin, South Australia. DEWNR Technical report 2016/03. Government of South Australia through the Department of Environment, Water and Natural Resources, Adelaide

Petermorra Springs comprise a number of vents in a drainage line. These are described as Erosional Channel Springs, a type of spring formation not found in springs in the Lake Eyre springs supergroup. Erosional Channel Springs occur in drainage lines where overlying sediments and confining layers have been eroded, allowing groundwater (spring) discharge to occur. All had been heavily impacted by cattle. Several carcasses were noted where cattle had become bogged at springs.

The spring vegetation at Petermorra largely comprised bore-drain sedge, Cyperus laevigatus. The endangered salt pipewort, Eriocaulon carsonii, was noted on one low spring mound.

Public House Springs 31st July

Public House Springs are also described as predominantly Erosional Channel springs and are fed by the GAB and other aquifers. They occur in drainage lines of the Petermorra Creek and can therefore be subject to flooding impacts (Keppel et al., 2016). There is an extensive array of more than two hundred spring vents. Although showing some impacts from cattle, these springs were in significantly better condition than those seen at Petermorra. This could reflect two aspects: the easier access for cattle at Petermorra and the much more extensive array of springs at Public House, meaning less concentrated stock impacts. The predominant spring vegetation was again bore- drain sedge, Cyperus laevigatus but many mounds contained mats of Eriocaulon carsonii. The mound spring bladderwort, Utricularia fenshami has also been recorded. The springs are described as having high floristic diversity but low macroinvertebrate diversity.

The FOMS group’s time at Public House Springs was somewhat limited: all agreed that a more thorough survey would be of much interest.

Reedy Springs 1st August

Trip Participants, L to R: Colin Harris, Duncan Ross-Watt, Caryl Ross-Watt, Bissie Lay, Bren Lay, Bruce Gotch, Sherrie Gotch, Chris Wenham, Brian Donaghy, Iris Iwanicki, Bernice Cohen, Rick Moore, Simon Lewis, Stafford Dow

On Saturday 1st August, the FOMS group drove north to join the Strzelecki Track, then on to Reedy Springs, still on Murnpeowie and just north-west of the ruins at Blanchewater.

Reedy Springs comprise more than three hundred spring vents, consisting of Sand Mounds and Erosional Channel Springs. The springs are thought to be fed by a mixture of GAB water and another aquifer (Cenozoic). A feature at Reedy Springs is an enormous sand mound several hundred metres in diameter. While some upper sections of the mound have dried out, much of it comprises active wetlands with Cyperus laevigatus and a scattering of small open pools. While C. laevigatus is by far the dominant wetland plant species, four bulrush (Typha) vents were also noted. Keppel et al., 2016 note that two relict species – Fimbristylis sieberiana (fringe rush) and Schoenoplectus subulatus (club rush) are also present at Reedy Springs, although in very limited distribution. Faunal diversity (macroinvertebrates) is low. The springs drain into a deeply incised gully which flows some distance to the east.

Reedy Springs also showed severe cattle impacts and several carcasses were noted, particularly in the vicinity of the Typha springs.

Reedy Springs marked the conclusion of spring visits by the FOMS group. This was a particularly interesting trip to some unfamiliar springs and FOMS thanks the pastoral lessees at Moolawatana and Murnpeowie for their cooperation. Special thanks are also due to FOMS member Kaaren Hawkes for her generous contribution towards costs incurred on the trip and Darren Niejalke for his advice and assistance with trip planning.