Grass-roots community organisation that aims to improve the natural condition of the Derwent catchment

Derwent Valley weed management program

Derwent Valley Roadside Weed Management Plan  

The Derwent Catchment Project has been implementing the Derwent Valley Municipality Roadside Weed Management Plan that we prepared for Council since 2015.  This structured approach to weed management along with highly accurate data recording is enabling us to see a marked and measurable reduction in weed species in all our target areas and bodes well for the environmental health of the valley. 

In parallel with the plan we have several key weed control programs running in the Derwent Valley region. 

Karamu 

Karamu is an introduced species from New Zealand which invades riverbank habitats and wet forest. New Norfolk has the largest infestation in the state, primarily along the bank of the Derwent. 

In the past, control programs have been undertaken on both public and private land, however there was still a significant infestation remaining. Tackling this tenacious weed across a range of tenures was posing a major challenge. In response to a need to build understanding of the weed and how to best collaborate across tenures, we developed a karamu weed management plan which has been guiding investment and control action.

The Entrance to the Valley

Granton Park, Lyell Highway and Boyer Road 

A program removing boxthorn and boneseed from Granton Park began in 2015–16 with support from Council and Crown Land Services. This program has gathered momentum and we are working with the Department of State Growth to tackle a range of declared weeds along the roadside from Granton Park to the ski club, and priority weeds on Boyer Road. Although there is still a long way to go, efforts to date have been substantial. There has also been an active private land program with information and support offered to those adjacent to the Lyell Highway around Granton where major infestations of boneseed and boxthorn are present.  

Murphy’s Flats 

Protecting the high conservation value of Murphy’s Flats is part of the motivation for weed control to be undertaken on the adjacent Lyell Highway. We are undertaking a program with State Growth to remove sweet briar from the wetland areas and have developed a 10-year action plan to guide investment and control. 

African feather grass 

This grass is a highly competitive invader of degraded pasture and riparian vegetation and is often spread via waterways. Dense infestations can also restrict stock movement, including blocking access to waterways, and large plants can totally block waterways and channels by trapping silt and debris. It spreads both from its highly viable and copious seed and from root fragments.  

There was a largely successful historical eradication project for this species in the Derwent Valley due to the risk it posed to agricultural productivity and water health of the region. Unfortunately, due to lack of coordinated monitoring and follow-up, the species has reappeared along the Plenty and Derwent Rivers and now threatens over 27 agricultural properties, many of which source irrigation water from these waterways. The Derwent Catchment Project has surveyed the known locations and developed a framework for prioritisation for the control of this species which will be used to support landholders and source funding for control. 

Tasmanian Wilderness World Heritage Area (TWWHA) weed working group  

A Derwent TWWHA weed working group including Sustainable Timber Tasmania, Hydro Tasmania, State Growth, TasNetworks, Norske Skog and Parks & Wildlife and their Working Neighbours Program has been facilitated by Derwent Catchment Project to address weed threats to the Derwent World Heritage Area and buffer. An action plan was developed in 2019, based on mapping of the roads adjacent to the WHA. Investment has been secured from all participants to undertake weed control, which will be reviewed annually to assess progress and schedule the coming season's control works. This includes Spanish heath control on the Gordon River Road into the TWWHA, which was the catalyst for this broader program.  

Derwent Catchment Project

PO Box 22 Hamilton TAS 7140  |  Phone (03) 6286 3211  |  facilitator@derwentcatchment.org