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History of TinarooHistory of the Lake & Dam area.
When you hear the word Tinaroo, you probably immediately think of Lake Tinaroo on which we can waterski, canoe, windsurf and even fish or sail. However, have you ever thought about why the lake was created? And how it came to be where it is today? I did some research and was amazed at what I found!
John Atherton, the first settler in the area named Tinaroo Creek in 1875. Discovery of tin and gold brought further settlement and ready market for farm produce. Years passed and into modern times, investigation began into increasing the generating capacity of the Barron Gorge Power Station. This was to meet the growing demand for power. This could not be done without a dam being built on the river to even out seasonal flow variations. After World War Two, the Qld Government began investigating the possibility of a major water storage area in the North. There were two possible sites: the Walsh and the Barron Rivers. The Barron River site was selected in preference to the Walsh because it could supply a bigger area for irrigation purposes, and it could supply water to the Barron Falls hydro.
The introduction of tobacco as a commercial crop in 1929 at Emerald Creek by Bartlett, Jenkinson and Veness, and an experimental farm at Tinaroo Creek to test the suitability of the area for commercial tobacco growing, brought a new farm crop to the area. Here were light sandy soils of, from 450 to 610mm depth, overlaying clay sub soil with sufficient fall to provide surface drainage. These soils were in the Mareeba-Dimblah area. Water was the main resource needed to achieve a good crop.
Farmers who had their paddocks on permanent water, like the Walsh River or a creek, had little problems with growing seedlings, but others had to cart water a long way for their plants, and even their households. By the 1932-33 season, it became clear that the rainfall in the tobacco growing area was totally unreliable, and farmers started to speak of irrigation. At the same time the city of Cairns, since 1925, had looked at the urgent need to increase the production of electricity by harnessing the waters of the Barron River at Barron Falls. However, it wasn’t until 1932 that tenders were let for the construction of the headworks, tunnel, pipeline, power station and transmission lines and the supply of other necessary plant.
This electricity station was set in operation by His Excellency, Governor of Queensland, Sir Leslie Wilson in November 1935. The conditions in the tobacco growing area as 1943 came along were extremely bad; there was insufficient rainfall for the growth of seedlings. The farmers had next to no income from the crops; not only from the water shortage, but also diseases like ‘frogs eyes’ and other fungi had reduced their income. At that time a committee was formed by farmers to bring to the attention of the State Government, the need for irrigation. The committee consisted of Shire Councillor Nicholls, Tobacco Association Director Wood and Director E.H. Short. With Short as a Chairman, Nicholls soon withdrew as he had next to no knowledge of tobacco growing. So the work was left to Woods to do the survey estimations and mapping of the area. Short prepared the report to Government and personally did the representation and general propaganda. In 1944 this committee presented a report, backed by maps (which were nearly the same as today’s), which showed the irrigated areas. The maps and reports were presented to the Minister Harry Bruce and Minister Harold Collins. This report resulted in an inspection by Sir John Kemp and staff of the Bureau of Investigation of Water Resources in 1945. Sir John and staff doubted however, that the cost would be justified.
By 1946, the work and representation this local Tobacco Committee had instigated, resulted in the establishment of the Irrigation and Water Supply Commission by the Queensland Government. In 1947 the IWSC became official and was headed by Mr T.A. Lang, an officer of the Victorian IWSC who was a commissioner. In the next three years the foundation was laid for this large irrigation project. In 1952 the Queensland Government authorized the construction of the dam. The site of the dam is on the Barron River where the river passes the Tinaroo Gorge about 63 miles or 102km from the mouth (near Cairns), and about 3.0km above the series of rapids known as Tinaroo Falls.
545 km2 of land was flooded to store the water for irrigation. This required the purchase of 20 farms, mainly in Kulara, and partly in the Danbulla district. The private landowners were represented by a private land valuer, Mr Carl Petersen. There were many court cases in the Atherton Magistrate’s Court to try to achieve a fair and decent price for each farm. The land around the Kulara township was good agricultural land, while the land in the Danbulla country was poor in commercial value, and used only for dairy farming. In the case that only part of a farm was flooded, the Irrigation Commission purchased the whole farm, and the land above the high water mark was handed to the Department of Primary Production. The Forestry Section of DPP planted 3,000,000 pine trees on the land. The area near Picnic Crossing, which did not go under water, was bought from the land owners and handed to the Kairi agricultural Research Station.
Farmers were allowed to remove everything that could be moved. The Kulara Hotel was totally dismantled, and the timber used to build herring-bone cow bails on an Upper Barron farm. The take over began in 1952, but farmers were allowed to use the land up until June 1953. On December 13, 1953, the official ceremony to mark the inauguration of the construction of the dam took place by firing the first shot in the foundation excavation. This shot was fired by the Minister for Agriculture and Stock, Hon H.H. Collins MLA. To construct the dam it required the placing of 223,000 m3 of concrete. The concrete was of the straight gravity type, 45m above river bed level. The dam has a base width of 35.5m, and a crest length of 5334m. The spillway is 76.2m long and 3.658m deep. Behind the dam 407,000 megalitres of water could be stored. This water comes from a 545km2 catchment area. Due to a 1300mm average rainfall, the high water mark of the water storage area created a 15km long storage area with a shoreline of 209km. In turn it created a 3,360 hectare reservoir, and gives a reliable yield for irrigation of 225,000 megalitres for power generation at Barron Falls Hydro Power Station and 72,000 megalitres in Kuranda. The full supply level is 670 metres above sea level, the flood inflow is estimated at 256,000 megalitres per day and the spillway discharge is 106,000 megalitres per day. The total cost of construction was $12,666,000.
Prior to the placing of the concrete, 191,134m3 of earth and rock had to be removed from the river bed and banks to reach sound granite foundation. However, when the overburden was removed from the alignment of the dam, it was discovered that there were two deep fractures in the rock foundations. To ensure that the dam would sit on a sound base, fissures were dug out and concrete was used to fill in the space created, by removing the cracked rock. Also, test drilling took place all along the future dam’s position to find out if any underground water was present, and could seep into the dam wall. Of all the 180 holes drilled, only one showed seepage, only 100 metres away, and well above the dam’s high water mark.
Two large steel conduits pass through the dam; each provided with suitable valves to discharge the water into the West Barron Main Channel on the first step of the journey to the farms in the Mareeba-Dimbulah area. An additional outlet was constructed to provide an adequate supply in the river below the dam. As with all dam constructions a large coffer dam was built, first to allow the water to be diverted from the construction of the individual blocks. In technical terms this is a mass, concrete, gravity structure. Its own weight holds it in place. It is not anchored to the granite rock bed in any way. There is no steel re-enforcement in the wall. This of construction was made possible with the use of low heat cement. When the cement is mixed with sand and water, heat is produced as a result of a chemical reaction that takes place. Its heat is quickly lost in this storage, and it results in very brittle concrete. Whereas, if the heat is lost slowly, a much stronger concrete is produced. 1.5 metre vertical pillars of cement were placed one at a time to allow the concrete to cure. You can still see the marks of each pour on the downstream side of the wall. The wall is made in monoliths, each measuring 15.2m in length. These monoliths fit together in the same way as bricks in a brick wall. Copper strips and rubber seals were imbedded in the mortar to make this wall waterproof. There are internal galleries inside the wall to allow for inspection and maintenance when necessary. As it happened, one of the concrete mixes in a monolith was faulty, but it was not discovered in time so that it could be removed. Now water is leaking out into the lower gallery. A 20mm diameter garden hose is picking up seepage and diverting the water to a drainage outlet. This is the only leak in this high dam. A wonderful job has been done by the concrete gangs. A subsidiary earthen embankment 6.401m high and 250m long, requiring 22,957m2 of earth and rockfill was constructed at a low saddle 1km south of the dam to prevent flood water spillage over this saddle during floods. Photo on left: Discharge of water during construction of the dam wall. Right (a): First construction downstream of dam. Right (b): dam 80% complete. Right (c): Partially completed monoliths. Right (d): Channel construction. Right (e): View of street in Kulara before damming.
Photos courtesy of the Neville Family, Tinaroo.
IRRIGATION AND WATER SUPPLY INFORMATION ON TINAROO DAM – RECAP OF FACTS
Catchment Area: 545 square kilometers
Average Annual Rainfall – 1,300 Millilitres
Storage Capacity – 407,000 Megalitres
Yearly Reliable Irrigation – 225,000 Megalitres
Assured Yield For Power Generation – 72,000 Megalitres
Reservoir Area – 3,360 Hectares
Full Supply Level – 670 Metres above sea level
Length of Storage – 15 Kilometres
Length of Shoreline – 209 Kilometres
Height of Wall – 45.1 Metres
Maximum Base Width – 35.4 Metres
Total Crest Length – 533.4 Metres
Quantity of Concrete – 223,000 Cubic Metres
Maximum Flood Inflow – 256,000 Megalitres Per Day
Maximum Spillway Discharge – 106,000 Megalitres Per Day
Period of Construction – 1953 to 1958
Cost in 1958 Dollars - $12,666,000
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