The Tharwa Fish Habitat Project trials the use of engineered log jams to improve fish habitat in the river reach and augment some existing rock groynes (outcrops of rock). The log jams are made of interlocking hardwood logs and rock. Some of the logs still have their roots attached, which helps the log jams maintain stability and provides the woody habitat that is an important native fish habitat.
The river will swirl between the log jams and groynes, scouring the sand, deepening the channel and creating pools that make it easier for the fish to pass this section of river. The river corridor will be further improved and stabilised with tree planting under the ACT Million Trees Program. Shrubs and macrophytes (plants that grow in or next to water) will be planted on the sand bar and river edge, larger trees and shrubs will planted up the bank and onto the floodplain. Weed control and site rehabilitation will accompany the planting. The ACT Government and community groups such as Waterwatch are monitoring the site and its aquatic life before and after the log jams are constructed to measure the effectiveness of the project and its potential for use at other sites.
