Long before the Merrimu weir was constructed the small village of
Coimadai supplied building lime to the city of Melbourne.
<strong>See Map B E8.</strong>
<br /><br />
Gradually, the irrigation of small crops and provision of water
for diary herds took precedence for the local economy.
<br /><br />
Coimadai township, with its lime kilns disappeared below the
waters of the lake with only the school and an occasional home
remaining. Many drive through the area as a better route to Tullamarine
Airport.
<br /><br />
Today, we have this magnificent park to enjoy along the banks of
the lake, and we use the water in our Bacchus Marsh homes while still
supplying irrigation for the crops we send to far-off Melbourne.
<br /><br />
These photos were taken on 3rd Dec 2018. On that day, the Merrimu
Reservoir contained some 11,030 Mega litres, which is 33.9% of the full
capacity of 32,516 mega litres. So, the water level does look a bit low.
<br />
Even with low water, Merrimu Reservoir is a great place for a
picnic.
<br /><br />
Facilities include car parking, toilets, wheelchair access, picnic
tables, covered tables, electric BBQs, swings; a dog on leash area. This
park is not designed for boats, because, as you will read, this lake is
for our drinking water. The Merrimu recreational area is open from
8.30am to 4.30pm daily.
<br /><br />
Merrimu is part of the integrated irrigation system from the three
water storages of Pykes Creek Reservoir that has a capacity of 22,119
mega litres (ML), Melton Reservoir that has a capacity of 14,340 ML and
Merrimu Reservoir, which has a capacity of 32,215 ML
<br /><br />
The Merrimu reservoir, on Pyrites Creek, has a surface area of 420
ha, and operates from a catchment area of about 85 sq km. The maximum
height of the embankment is 45.3m, with a length of 400m. The Spillway
has a crest length of 30m, and a discharge capacity of 26,000 mega
litres a day.
<br /><br />
None of these storages were designed to manage floods. They simply
store water for various uses &ndash; mainly irrigation, and in some
cases drinking water. They have fixed crest spillways; so that once they
are full any excess water coming into the reservoir will flow over the
spillway into the river or creek downstream. Therefore, the managers,
Southern Rural Water, do not have the ability to deliberately surcharge
(over full) the dams.
<br />
<h2>For Provision of Water, not for Flood Mitigation</h2>
The reservoirs do not have ability to pre-release enough water to
have an effect on a possible flood, but they can help reduce flood peaks
a little by temporarily storing water if they have room. None of them
are large storages, however once they are full; they have little impact
on flows.
<br />
The Merrimu reservoir provides drinking water to local towns and
irrigation water to the Werribee Irrigation District. Water levels can
vary throughout the year.
<br />
<h2>Southern Water</h2>
The Southern Water Commission has its head office in the regional
smaller town of Maffra, and operates some 93 major dams and many smaller
structures. These storages supply water through channels and pipes
across much of Victoria.
<br /><br />
Their information pages say &ldquo;In an average year ten times
Melbourne&rsquo;s annual water consumption is used on farms and in rural
communities.
<br /><br />
&ldquo;The produce grown contributes greatly to the economy of the
state. Dairy products, fruit and vegetables, livestock and wine are just
some of the many products that depend on this water.
<br /><br />
&ldquo;The Merrimu Reservoir and associated structures, which
include diversion weirs and tunnels, supply water to the Bacchus Marsh
and Werribee Irrigation Districts where much of the fruit and vegetables
for the Melbourne Market is grown.&rdquo;
<br /><br />
<h2>History</h2>
The information boards at the recreation park provide a very
interesting, and fairly detailed, description of life and activities
that would have had the name Coimadai in the mind of many a builder in
early Melbourne, and later, many buyers of fruit and vegetables at the
Victoria Market. These days a few buyers at Footscray&rsquo;s major
market would know the region.
<br /><br />
Let us quote from the boards:
<br /><br />
&ldquo;Southern Water Commission of Victoria -
<br /><br />
<h2>History of the Coimadai Valley</h2>
&ldquo;The township of Coimadai was established in the
1850&rsquo;s after rich lime deposits were discovered in the valley. The
name Coimadai is Aboriginal for &ldquo;the old man kangaroo
resting&rdquo;.
<br /><br />
&ldquo;By the mid 1860&rsquo;s four lime burning kilns were in
production, and some twenty families lived in the area. At its peak, a
workforce of some 100 was engaged in the lime burning industry. By the
1920&rsquo;s numbers had reduced to 30 and by the 1930&rsquo;s only half
that number remained.
<br /><br />
The Lime industry created a number of associated activities, which
gave employment to the small community. Wood was cut and hauled to the
kilns, lime was quarried nearby, and the kilns loaded and fired, lime
was crushed, bagged and carted. Although lime crushing continued until
1986, lime burning ended in the 1950&rsquo;s, as cement took over in
building construction. Agricultural lime, also known as dolomite,
produced without the burning process, was continued until inundation of
the dolomite pits by the Merrimu Reservoir.
<br /><br />
<h2>Coimadai Township</h2>
&ldquo;The township consisted of the Foresters Arms Hotel, a bush
hotel, the Coimadai School No 716, built in 1863 and still in use, and a
shop.
<br /><br />
&ldquo;In 1926 a community hall was built which subsequently burnt
down on 1937. It was reconstructed and later moved to Grant St Bacchus
Marsh where it remains today.
<br /><br />
&ldquo;The valley also developed as a farming community with
sheep, beef and diary cattle and cereal crop production.
<br /><br />
&ldquo;Another landmark of Coimadai was the mineral springs which
during the last century was famous internationally.
<br /><br />
&ldquo;A Mr Bower is said to have entered a sample of the water in
the 1880 Paris Exhibition, winning a gold medal. In 1936, a company was
formed to bottle the water. A shortage of bottling supplies during the
Second World War forced the closure of the Company.
<br /><br />
&ldquo;Apart from the School and the home of the Bennett family,
the only remaining landmark of the old township were the lime kilns, the
last of which was flooded by the enlargement of the Merrimu reservoir in
1986.
<br /><br />
Lime Burning
<br /><br />
&ldquo;After quarrying, the limestone and wood was placed in the
kilns in layers. Large wood was placed in the kilns first, forming a
platform one to two metres high. Alternate layers of limestone and wood
were then loaded until the kiln was full.
<br /><br />
&ldquo;The wood was fired and a heat of 940 degrees centigrade had
to be reached to separate the carbon-dioxide from the calcium in the
limestone. As the wood burnt the limestone dropped down the kiln and was
drawn out the bottom by shovel for loading into the crushing
machine.&rdquo;
<br /><br />
The Commission&rsquo;s board has some photos: Alkemade&rsquo;s
quarry circa 1910. And Alkemade&rsquo;s Lime Kiln circa 1916.
Dibley&rsquo;s Lime Kiln, February 1986. And Lime wagon carrying
Alkemade lime, circa 1900.
<br /><br />
&ldquo;The lime was loaded into one hundredweight bags by hand and
stored or transported to Bacchus Marsh to the railway. Wagons piled high
with up to 250 bags of lime were a familiar sight in Coimadai. More than
six horses were needed to pull the heavy wagons out of the valley. Once
the hills had been negotiated, two horses were unhitched to make their
own way back to Coimadai.
<br /><br />
&ldquo;The Rural Water Commission commissioned a number of
investigations on the history and significance of the remains of the
lime burning kilns before the last one was inundated in the enlarged
Merrimu reservoir. The results were published in three separate volumes
and these can be found in local libraries in the area.&rdquo;
<br /><br />

<strong>The second board of Southern Rural Water</strong>
quietly explains the thoughtfulness of the engineering practices
throughout their storages, and especially in regards to this system of
storages. Mind, some of the statistics are a little dated, but they show
how, over long periods of time, this area has contributed locally to
Bacchus Marsh, regionally to Melton and Werribee, and further to the
state&rsquo;s capital, Melbourne.
<br /><br />
&ldquo;The Rural Water Commission stores and distributes water to
country regions of Victoria where it is used for irrigation on farms and
for supplying many towns and cities.
<br />
&ldquo;The network of some 93 major dams and many smaller
structures supply water through channels and pipes across much of
Victoria. In an average year ten times Melbourne&rsquo;s annual water
consumption is used on farms and in rural communities.
<br /><br />
&ldquo;The produce grown contributes greatly to the economy of the
state. Dairy products, fruit and vegetables, livestock and wine are just
some of the many products that depend on this water.
<br /><br />
&ldquo;The Merrimu Reservoir and associated structures which
include diversion weirs and tunnels supply water to the Bacchus Marsh
and Werribee Irrigation Districts where much of the fruit and vegetables
for the Melbourne Market is grown.
<br /><br />
&ldquo;Many Commission storages are available for recreation
including swimming, fishing and boating. Storages like this one that
supply water directly to urban communities must remain closed to protect
the quality of the water.
<br /><br />
&ldquo;The sketch plan (on their board) shows how Merrimu
Reservoir fits into the distribution system for this area. Water to fill
this dam is diverted by tunnels from nearby catchments.
<br /><br />
&ldquo;When additional water is required in this system, Merrimu
dam will be raised a further 7 metres in height. This raising will
double the amount of water in store to 74,000 mega litres.
<br /><br />
&ldquo;The new top water level will be below the fences at the
edge of this park and as indicated by the marker.
<br /><br />
&ldquo;Further details of this project and literature on the
activities of the Water Commission can be obtained by ringing the
Publications Office on (03) 508 1277&rdquo; (Let&rsquo;s update this to
03 5139 3100 or 1300 139 510 and E: srw@srw.com.au.)
<br /><br />

<h2>1. Lerderderg Weir</h2>
&ldquo;Lerderderg Weir diverts water from the Lerderderg River
through a 4 km long tunnel into Goodmans Creek. A portion of the
resultant combined flow in Goodman&rsquo;s Creek is then diverted at
Goodman&rsquo;s Weir via a 1.6 km long tunnel into Pyrites Creek just
above Merrimu Reservoir. Construction of these diversion works has
enabled Merrimu Reservoir to be provided with adequate inflows.&rdquo;
<br /><br />
<h2>2. Merrimu Outlet Works and Pumping Station.</h2>
&ldquo;Water released from Merrimu Reservoir flows down Pyrites
Creek to Melton Dam and subsequently down to the Werribee Irrigation
District.
<br /><br />
&ldquo;The pumping station below the dam lifts water via pipelines
to the urban areas of Bacchus Marsh and Melton.&rdquo;
<br /><br />
<h2>3. Bacchus Marsh Irrigation District</h2>
&ldquo;Located on the Bacchus Marsh Plain, this area was once a
large swamp. It is now a highly developed agricultural areas
specialising in diary farming, horticulture and market gardening.
<br /><br />
&ldquo;Total Area of 1,994 ha. With 163 irrigated holdings, being
serviced by 19 km of concrete channels and 26 km of pipelines.
<br /><br />
&ldquo;The production from this area is Pasture for 410 ha,
Orchard on 353 ha, Market Gardens on 300 ha, and other products on 150
ha.&rdquo;
<br /><br />
<h2>4. Werribee Irrigation District.</h2>
&ldquo;Werribee has become one of Victoria&rsquo;s premier
vegetable growing districts, having rich alluvial soil, and efficient
irrigation and drainage system, and being close to Melbourne&rsquo;s
markets.
<br /><br />
&ldquo;Total Area 3,699 ha with 258 holdings, being serviced by 64
km of concrete channels, six km of pipelines and 60 km of drains.
<br /><br />
&ldquo;The production from this area is Market Gardens on 2,066
ha, Pasture on 760 ha, and other on 125 ha.&rdquo;
<br /><br />
<h2>Footnote:</h2>
Jurij Karlovsek, (j.karlovsek@uq.edu.au, ph 07 3443 1686) of the
Engineering Department University of Queensland, is the founding
chairman of the Young Members Group, within the World Tunnelling
Association. He is originally from the small central European nation of
Slovenia. My co-owner of Pocket Books, my wife Nevenka, B.Maths(Hons)
&amp; M. Cyber Security, is also from Slovenia, having been the chess
champion there, and is now the honorary Slovenian Consul for Queensland.
<br /><br />
I was chatting with Jurij about the Tunnelling Association, saying
there are not very many car tunnels here. He said there are thousands of
sewerage and water tunnels. Then I truly realised how important is this
chairmanship from Australia of such a World group. The engineers who
designed these tunnels, dams, spillways and storages would be pleased
that Australia, in conjunction with Slovenia, has had this chairmanship.
<br /><br />
Co-incidentally, Jurij&rsquo;s university is featured on the front
cover of our Southern Downs Qld Pocket Book for their solar cell farm
near Warwick. See PBezy.com.au.
<br /><br />
Of course Slovenia is a little more famous and well known for
another person - Melania, the wife of Donald Trump.
<br /><br />
Kind regards,
<br /><br />

<strong>Gerry Clarke</strong>
, B.PED. (USC) and XC 1969 (Kew Vic)
</p><br />
<p>P.S. While the water storage is called &lsquo;Merrimu&rsquo;, the
	dam is just north of Merrimu, and within the Coimadai locality.</p>