The Traveston dam is designed to permit the overflow of large
scale meteorological events. Refer to Hydrology Mary Valley
Currently the Mary River has ceased flowing above the dam site
(CM October 2009). The Mary River mirrors the Stanley River which is our main
water supply. It has the backup storage of the Wivenhoe dam and even that dam is
proving inadequate to control major events.
It is my view and others that the 85% requirement of all 
water
that flows in the Mary River must reach the River mouth is made up almost
entirely of flood water. We now know for certain that flood water is
damaging to the eventual point where it enters the sea.
Here again, the use of the "mean annual flow"
includes all of this flood water. It is not difficult to envisage a distortion
to percentages when most of the water is flood water and especially the very
high rainfall events inclusion.
The following give one an appreciation of how our main water
supplies fall and why they are our main water supply.
Pattern of Rainfall
The Mary Valley is the site of the proposed Traveston 
Dam. Its
catchment is adjacent to the Somerset Dam catchment. Its rainfall operates in
the same way as the Somerset. A
comparison of the rainfall of the two catchments is attached.
River heights
There are no inflow figures as there is no Dam. However 
the
Bureau of Meteorology do have the River 
heights
at Gympie located below the Dam. They effectively replace inflow assessments. In
addition their web-site records the major floods and it is also attached. These
majors date back to 1893 and are mirrored by the "uncommon events" of
the Somerset with the exception of 1968.
Photos : Bureau flood heights at Gympie and Maryborough
together with major flood heights at various location on the Mary River
You will have noticed that the Bureau labels the
"floods" 
Minor,
Moderate and Major. It also gives the River height at Gympie. It is therefore
possible to match the rainfall with the River heights.
