Waterwatch Autumn 2024 Update - SACTCG

The view from Coordinator’s desk:
Welcome to another Southern ACT Waterwatch Catchment Update.
Last Autumn saw above average rain work its wonders on our waterways. As always there were were mixed blessings, with many waterways bearing the brunt of chronic catchment health issues such as high phosphorus diets, either from urban land use or as a hangover from bush fires. A big positive was the lack of erosion episodes that often dump loads of sediment into rivers such as the Paddy’s. Out rivers were beautifully clear.
Autumn is a ‘BugBlitz’ season, and I was privileged again to be joined by teams at almost every site. Another highlight was the opportunity to ride on the coat-tails of our wonderful Brindabella Venturers as they introduced Waterwatch to hundreds of Scouts (including Joeys, Cubs, Venturers and Rovers) from all over Australia at the Governor Generals Camp.

Rainfall statistics courtesy of Bureau of MeteorologyCheers, Martin Lind
Waterwatch Coordinator.

WW Teams update:
The Point Hut Pond team of Sharae, Sabrina and Alannah finished this season. Sharae had been looking after this lake since 2021 and was joined by Sabrina and Alannah last year. They brought their Waterwatching skills from their time with Lake Tuggeranong College’s award winning Sustainability Unit. The pond has been seamlessly handed on to Sam who had been driving down to the Naas River to do Waterwatch since 2021.

Sam enjoying the waterbugs at her new locale.

Around the Rivers and Creeks:
All our rivers and creeks had crystal clear water associated with mostly moderate flows in spite of the above average rainfall over much of Autumn. The lower Naas and Gudgenby Rivers carried significant levels of phosphorus pollution compared to the other rivers. Tuggeranong Creek, by far the saltiest, also had persistent levels of phosphorus and elevated pH in its concreted section.
Everywhere we hunted for waterbugs we found lots of blackfly larva (Order;Diptera, Family;Simuliidae). These funny little bottle shaped maggots move like leeches as they stick their fat bottoms to rocks with a natural form of ‘Velcro’ and are sticklers for water that is clear and fast flowing.
The top sites for waterbugs this autumn were the upper Cotter River at Spur Hole and Gibraltar Creek. Waterwatch teams caught a good variety of waterbugs in the Murrumbidgee, Paddy’s, Naas and Gudgenby Rivers. At Uriarra Crossing the Murrumbidgee had the highest diversity score of any survey in the Southern ACT with no less than 14 types recorded. However, Water boatmen (Order;Hemiptera, Family;Corixidae) outnumbered everything else and they are not indicators of terrific water quality. The diverse mix was also often made up of other ‘tough’ bugs, like snails and worms. The star indicator of great water; stonefly larva (Order; Plecoptera) were few and far between. The pest fish ‘Gambusia’ was also found at every survey on the Murrumbidgee River.

Rangers Dave and Jack at Spur Hole Fist full of dragonflys at Paddy’s river

Around the Lakes and ponds:
The lakes were slightly muddier than the rivers this autumn, with the exception of Guises Flat Dam, Isabella Pond and to a lesser, extent Stranger Pond. The high rainfall forced phosphorus pollution into all of our still water bodies and dissolved oxygen levels fell as algae and bacteria enjoyed the feast. The main drain to the east of Isabella Pond also carried massive amounts of nitrates, another measure of decaying matter. The elevated levels of salts and minerals in Isabella Pond and Guises Flat Dam most likely originated from Tuggeranong and Guises Creeks respectively. The good news was the long awaited exit of the Azolla covering the old Cooleman Ridge dam.
Bug wise, most still water sites had good diversity with more than 8 types of critters caught but, as with the rivers, it was hard to see the other bugs past all the water boatmen. Point Hut and Stranger Ponds had not much other than water boatmen in the nets. If Gambusia were sardines we could make a fortune from Lake Tuggeranong.

Casey in Lake Tuggeranong Tony G at Stranger Pond

Around Tidbinbilla and Namadgi
If you wanted find Stonefly larvae and their sensitive little soul buddies Mayfly, Caddisfly and Alderfly Larvae(Orders; Ephemeroptera, Tricoptera & Megaloptera respectively) you needed to head to the hills this autumn as they were hiding in abundance in the national park and Tidbinbilla. Crystal clear water with moderate to low flows and plenty of oxygen provided the perfect homes. Joining them in the Naas River were huge dragonfly larvae, freshwater sponges and over 8 kinds of caddifly.
Everywhere the water quality still has phosphorus and, in the Orroral River, nitrate issues. Fire residues are still the likely culprit. Salt levels were also higher than in the Cotter River to the west. An interesting side benefit of regular Waterwatching in the national park was the chance to bust a party of interstate folk hunkered down at Frank & Jack’s Hut. They considered themselves above the law and had chomped through a number of locked gates in a 4WD frolic through the park. They’re exploits earned them a hefty fine.

Scout group at Frank & Jacks Hut Casey in the Orroral River

Cristy & Tony at Tidbinbilla

Around the schools and youth groups

This Autumn I had the pleasure of once again teaming up with some pretty cool young people, this time from all over the country. The A.N.U.Intrepid Landcare group joined me at Pine Island for bug hunting. Trinity Christian College Yr 11 Biology undertook their mini C.H.i.P project at Isabella Pond that has now become integrated into their curriculum. Jed, Yolandi and I spent a week at the Governor General’s House in Yarralumla helping the Brindabella Venturers undertake a well orchestrated array of Waterwatch activities as part of the National Governor General’s Scout Camp. I also had a combined team of Venturers, Scouts and Rovers join me and Waterwatchers Casey and Richard on a bug hunt in Namadgi NP.
Finally St Mary MacKillop College Environmental Science class looked at the water quality of Isabella Pond and their Engineering students used our tests to assess the effectiveness, or otherwise, of their water filtration projects.