Waterways of the Merri Catchment flowing slowly through emergent vegetation; and the lower 30% is a slow, non-uniformly flowing stream. 3.3.2 Summaries of the Significant Tributaries This summary is based on the work of N.M. Craigie & Associates (Craigie, 1994). They divide each stream into a series of reaches based on generally similar features such as channel, bank and verge characteristics. This section deals with the channel origin and the flow character alone and lists the creeks as they join the Merri Creek from its headwaters to its mouth. It is worth noting that N.M. Craigie & Associates acknowledge that the classification of the catchment in this manner is quite broad and can be refined by more detailed study. However, this is the best available work that covers the whole watershed. Mittagong Creek This creek is the northernmost headwaters of the Merri Creek system but joins Wallan Creek before the Merri Creek near the Hume Freeway. Craigie classed it as having only one reach. From its beginnings to its confluence with Wallan Creek, Mittagong Creek is 5 km long. Although the channel is essentially natural in origin, there has been extensive modification to it. There are several large on-stream dams and the stream from William Street in Wallan to its confluence with Wallan Creek has been straightened somewhat. The flow is generally negligible but there are disconnected but relatively permanent pools. The dams constructed obviously control the flow. Wallan Creek This creek in the headwaters of the Merri Catchment arises on the south side of Pretty Sally on the Great Dividing Range. It flows south then east through the township of Wallan into the Merri Creek near Wallan East, a total distance of nearly six kilometres. The creek has been divided into four reaches. The uppermost reach, which has not been described by Craigie, flows through farmland and the urban fringe a distance of 1.2 km. It is likely that the form has not been altered much. The sections of the creek downstream of the township, 65% of the total length (5.35 km), have been substantially altered. These alterations include channel enlargement, installation of a low-flow pipe, channel straightening, channelisation and de-snagging. The uppermost reach is characterised by a stream flowing slowly through emergent vegetation. The middle reach has not been classified as it has a low-flow pipe. The section from the Hume Freeway to the Merri Creek does not normally flow but has disconnected and semi-permanent pools. Page 50 State of the Environment Report - Introduction Strathaird Creek (Airfield Drain) This creek has its origins in the hills to the west of Wallan, from which it flows southward until it reaches Rowe's Lane where it turns east and flows into the Merri Creek. The point at which it is joined by Taylor's Creek it is termed the Airfield Drain. Craigie divided the creek-drain system into two reaches and the total length of the system is approximately nine kilometres. Of the total length of the system (8.6 km), 56% has been drastically modified to an unlined artificial drain while the upper 3.8 is in a close to natural state. The flow regime of the upper part of the creek is likely to be discontinuous but relatively permanent pools with negligible flow. Downstream of Rowe's Lane the creek-drain system is characterised as a slow flowing stream filtered through emergent vegetation. Taylor's Creek Taylor's Creek arises on the southern side of Pretty Sally on the Great Dividing Range and flows southwards past Wallan before joining the east flowing Airfield Drain at Macsfield Road and then uniting with the Merri Creek at Herne's Swamp south of Wallan, total length of approximately eight kilometres. The creek has been divided into four reaches. Of the total length of the creek to the Airfield Drain (5.6 km), 23% is highly modified (straightened and de-snagged), 14% has slightly less modification (de-snagging) and 63% is largely unmodified. The flow character of each of the three reaches is slow and filtered through emergent vegetation. Unnamed Western Tributary This minor tributary drains a small area northeast of Mt Fraser. Although Craigie described the lower two kilometres only as one reach, the upper one kilometre of the stream appears (from the topographic map) to be in a largely natural state. The reach described by Craigie is an artificial unlined drain. Therefore 66% of the creek has been highly modified. The flow in the lower section is slow and filtered by emergent vegetation. Bald Hill Drain This small tributary drains an area northeast of Bald Hill. Again Craigie has described the lower 1.5 km only (as one reach), although the drain begins another 2 km further upstream. The reach described by Craigie is a natural channel that has been extensively modified by straightening and de-snagging. It appears that the remainder could be classed similarly. The flow has been characterised as slow and filtered through emergent vegetation. Kalkallo Creek System This system of drains and creeks draws water off the hills west of Beveridge flowing southward to join Merri Creek near Donnybrook Road. Five drains unite west of Kalkallo to Page 51 Waterways of the Merri Catchment form Kalkallo Creek proper. Craigie has described three of these drains and termed them Kalkallo Creek West Leg, Kalkallo Creek Centre Leg and Kalkallo Creek East Leg. The state of the channels of this drainage network is that nearly 36 km of channel length, 14.6 km (41%) is in nearly natural (with only slight modifications) whilst 20.7 km (59%) is unlined channel. Except for the East Leg which flows only after rainfall, the flow character of all the streams is one of discontinuous but semi-permanent pools of water with negligible flow. Malcolm Creek This western tributary joins the Merri Creek a little north of Craigieburn. The creek has its headwaters in an area of open forest between Mickleham and Mt Ridley from which it flows southwards through open pasture until it reaches Craigieburn whereupon the creek turns eastward and flows into the Merri Creek a total distance of approximately 8.3 km. Craigie divided the creek into just two different reaches - that above the Hume Freeway and that below. The two reaches are in a close to natural state with only minor de-snagging, however the lower reach has greater inputs of rubbish. The whole of the stream flow is very slow to non-existent and is characterised by disconnected but relatively permanent pools. Aitken Creek Another western tributary, this creek joins the Merri Creek just south of Craigieburn. The headwaters of this creek are near the Old Sydney Road about 5 km west of Craigieburn from which it flows in a southeasterly direction through open pasture and then the township of Craigieburn until it joins the Merri Creek a total distance of approximately eight kilometres. Neil Craigie divided the creek into three reaches; that above the Craigieburn Golf Course, the section through the golf course and the section through the township to the Merri Creek. As a percentage of the total, over 81% of the creek is kept in a nearly natural state and the character of the remainder, whilst extensively modified, is not completely destroyed. From the headwaters to the golf course the flow is almost non-existent and is characterised by disconnected but relatively permanent pools. There are also many on-stream dams, which in times of storm activity must disrupt the natural flow of the creek. The flow through the golf course is slow and filtered through emergent vegetation. Through the township the flow is slow and non-uniform having runs, glides and pools. Curly Sedge Creek This medium-sized tributary arises northeast of Summer Hill and joins the Merri Creek near O'Hern's Road, a distance of around 7.5 km. Craigie has classed the whole creek as one reach. The creek is in a basically natural state with only minor de-snagging. The natural flow of the creek is negligible with the stream consisting of discontinuous but relatively permanent pools. Page 52 State of the Environment Report - Introduction Campbellfield Creek This small creek is a tributary of Merlynston Creek that runs parallel and adjacent to the Hume Highway. It begins at Mahoney's Road and enters Merlynston Creek in the Fawkner Crematorium, a length of 2.2 km. Although Craigie has not examined this creek, it is apparent from the topographic maps that the section below the retarding basin to Box Tree Road (a distance of 0.5 km) has been straightened and is probably channelised. It appears that the creek is an intermittent stream. Surrounding urban development has probably caused an increase in the flow during storm events. Merlynston Creek This creek is one of the western tributaries of the Merri Creek and has its headwaters a little north of Barry Road near the Upfield railway station. It flows southward for approximately seven kilometres through the suburbs of Broadmeadows and Glenroy and then through the Fawkner Crematorium, finally entering the Merri Creek two hundred metres above Coburg Lake. The creek has been radically altered by the industrial and urban development. Neil Craigie has divided the creek into five reaches. Of the total length of the stream (some 6.75 km), 43% is either a pipeline or an open concrete channel and a further 27% has had major modifications. Only 30% of the stream remains relatively unmodified. For the most part the flow in Merlynston Creek is either very slow or negligible.