08 December, 2015

WATER TESTING RESULTS

CAPERTEE RIVER CATCHMENT WATER TESTING PROJECT, Nov. 2015
In October-November 2015 Capertee Valley Landcare undertook a salinity survey of the Capertee River
catchment streams, from Airly to Bogee to Glen Davis and beyond. Samples were collected by Julie
Gibson and Vicki Powys, with extra input from community members. The project is ongoing. We have
produced a map of the valley, showing salinity readings from 31 locations, taken in the last two weeks of
November 2015.
We found that:
· There is a pattern of salinity in the valley, with low salinity at the headwaters, and streams
becoming more saline along the way.
· Bores were generally much more saline than streams, indicating a salty water table below the
land surface.
We made the assumptions:
· Streams need to be sampled within, say, a fortnight when there is no rainfall, to compare “like
with like”.
· Heavy rain will dilute streams and rivers, and the salinity readings will usually be lower,
especially (for example) if the Capertee River was in flood.
Our lowest (best) reading was from a spring on Mt. Airly, and our highest (worst) reading was from
Bourbin Creek, where a white salt crust could be seen in the partly dry creek bed. Parts of Bourbin
Creek are one-fifth as salty as sea-water!
We are continuing to collect historic data and rainfall records, and will periodically re-test streams in
Capertee Valley.
What causes salinity?
Capertee Valley is, geologically, a hot spot for salinity problems. The rock strata were laid down in salty
seas so there will always be salt underground. When the water table rises, the salt comes up with it. As
the water evaporates, the salt can show up as white patches on the ground. Deep rooted trees help
keep the water table down. Grasses are shallow rooted and allow the water table to rise. Soil erosion
can also release salinity into the streams.
Acknowledgments:
We adapted the Bird Brochure map, which was used with permission from Capertee Valley Alliance.
Our water testing kit was loaned to us by Central Tablelands Local Land Services.
Contact:

Capertee Valley Landcare, Julie Gibson, 0263797317

click on image to enlarge


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