The Mitta Mitta Rehabilitation Project

By Michael Broughton, Project Officer, North East Catchment Management Authority

The Mitta Mitta River in northeast Victoria ows through Dartmouth, Mitta Mitta and Eskdale. There are two large storages located on the river; Lake Dartmouth and, Lake Hume. Both are known as great recreational fishing waters.

The Mitta Mitta River is known for fish species including, trout in the upper reaches and, cod in the lower. The Mitta is a highly regulated system with flows generally held back during winter and then, during the demand season for irrigation and power generation, the river can run quite high for several months. These unnatural flow regimes can make it hard for our native fish to survive so adding habitat to this system is highly beneficial.

The North East Catchment Management Authority (CMA) has a long running program along the Mitta Mitta River, working in conjunction with the Murray Darling Basin Authority (MDBA) and Goulburn Murray Water (GMW), to maintain bed and bank health.

The Mitta Mitta Rehabilitation Program involves discussions with landholders and other users of the Mitta. These stakeholders have supported works to promote the health of the Mitta, along with attempting to see more habitat placed back into the river to improve the native fish population.

In stream woody habitat, plays a vital role in a range of ecological functions for native fish, including habitat, spawning sites, refuge from predators and connecting home ranges for migrating species. Increasing the amount of woody debris in the system is recognised as a priority by key stakeholders and the community.

Several studies were undertaken, by both the North East CMA, MDBA and the Arthur Rylah Institute, to monitor and study the impacts of the Dartmouth Dam on the Mitta Mitta River. These studies included, investigation of cold water releases from Lake Dartmouth, channel change, instream habitat and, fish numbers. Investigations also have been undertaken through electro-fishing and tagging of native fish to monitor their movement along the river as well as, a 2015 “snag” census of the lower reaches which showed habitat in this part of the river to be severely depleted.

These studies, along with meetings held with landholders and local fishing clubs, continue to inform the direction of future works along the Mitta Mitta River.

With the support of the MDBA and GMW, the North East CMA successfully applied for the Recreational Fishing Grants Program in 2014, where a three-year project was funded to implement instream fish habitat works starting in 2015. The project will work from Eskdale down-stream to the high-water mark of Lake Hume. The project also aims to increase instream habitat within the Mitta River to maximize survival rates and to provide spawning opportunities for native species in the system, in particular cod, with follow-up monitoring to evaluate the effectiveness of the installed habitat.

A meeting was held with the local fishing group and interested landholders to create a small committee and to select sites for the project. Local knowledge, combined with Arthur Rylah Institute’s depth and habitat load maps, was used to pinpoint the areas that would benefit most from adding habitat.

The project committee identified sites where timber was already in place but with gaps that could be filled to create large sections of timbered water. It also placed timber in areas totally devoid of habitat to provide comparison sites which would obtain a better picture of how the fish moved through the system and, to improve fishing in the areas without current habitat available to hold fish.

Finding the right type and size of timber was difficult. Over the years fallen timber along the river flats has been used either for fence posts or firewood, and what is left is generally important habitat best left on the ground.

Timber was sourced from from multiple sources.

When sourcing, we needed to be mindful of not taking timber in certain areas along the Mitta Mitta River where the threatened native Booroolong tree frog habited. Fortunately, through word of mouth, members of the fishing clubs and good publicity on the radio, we sourced timber from many areas. Timber was sourced from; a cleared part of a new housing estate, six semi loads from a large centre pivot at a Lucerne farm, from a supplier in NSW, a Pine plantation and, even the local council helped the program. We found that social media was a great way of engaging with the community and to ask for ideas or help, and had great feedback using Facebook and Twitter.

Once sites were identified and timber sourced, the works began. The North East CMA combined the habitat project with the Channel Capacity Program on the river with MDBA and GMW. This helped to minimize costs associated with heavy machinery. We found that that addition of fence and re-vegetation at these sites complemented the in-stream habitat works by adding value and increased awareness of both projects! This helped save some money that could then be used for more timber or more sites and, for more fish.

During the project more than 250 separate pieces of timber were placed into the river to create extra areas of habitat for our native fish at more than 20 different sites. We developed signage to let people know what we were doing and, to help deliver the message, to the community, that these grants were funded by the Victorian Government through revenue raised from fishing licenses.

250 separate pieces of timber 20 different sites were placed into the river

As part of site planning and preparation it was also necessary to be mindful of any possible impacts these habitat loads may have on bed or bank erosion along with impacts to flows. Thankfully there has been a lot of study done to investigate these concerns and, if placed and secured correctly, it has been demonstrated that reinstating timber has great benefits to waterway health. Benefits include, helping move sediments through the system by creating roughage in the bed of the waterway or, simply by creating a new home for macro-invertebrates which in turn is a food source for fish and other animals in the water.

The placement of timber involved work to ‘pin’ in place smaller timber or ‘link’ it in with larger, heavier timber that would ensure it doesn’t float away and cause issues for assets located further downstream.

In March of this year, Arthur Rylah Institute completed the final monitoring run for the project While the data has yet to be formally collated, all new habitat sites held fish and, as can be seen from the pictures, there was a good spread of large and small cod throughout the sites. Whilst cod were the focus of the monitoring, trout, redfin and freshwater crayfish were also found. Currently, I can’t give solid data on what or why, but it certainly shows that, “… if you build it, they will come”.

Zeb Tonkin from the Arthur Rylah Institute with a good sized Murray cod caught where the semi loads of timber were placed.

In the future, the North East CMA hopes to receive another Recreational Fishing Grant to further monitor these sites and gain a better understanding of how and where to place timber that best satisfies the fish’s requirements. While there is some basic knowledge on the science of placing timber, such as the cod like deep slow velocity areas closer to the banks and trout cod like habitat in the middle of the bed of the waterway, we never stop learning nor trying to find better ways to do these types of works.

The landholders and local fishing groups have been extremely supportive of this program and would like to see it continue. The North East CMA is also again keen to be part of the program, therefore, we will work together and make another application that addresses further and future areas of this iconic angling waterway.

Recommended for you

Subscribe to our mailing list

Join our 50,000+ subscribers in receiving our Fishing Lines News delivered straight to your inbox. Don’t miss out on all the issues affecting your fishing, projects improving your fishing and opportunities to have your say about your fishery.

* indicates required
Communication Preferences (tick all that apply)