Introduction
Groundwater in the Padthaway area in the state's South East is
part of the aquifer system that is present throughout the South
East. This groundwater is an important source of water for agriculture.
>> More
The Padthaway area is dominated by the upper unconfined aquifer
with the lower confined aquifer either thin or absent in parts.
The EPA monitors water quality in the unconfined aquifer in the
area. This aquifer is at most risk of being affected by pollution
because the water table is within 5 metres of the surface. The
unconfined aquifer is susceptible to contamination from past and
present agricultural and industrial sources.
The main issues regarding the groundwater quality in the Padthaway
region are high nitrogen levels (mainly as nitrate)
and high salinity.
Water quality assessment
Water quality is assessed as being in good, moderate or poor
condition by interpreting water chemistry data in the context
of protecting various environmental values. >>
More
Groundwater samples are collected annually from 7 bores in the
Padthaway area. The indicators that are measured in the unconfined
aquifer in the Keith area are nutrients (nitrogen and phosphorus),
heavy metals, arsenic and salinity. The environmental values that
need to be protected are freshwater ecosystems, irrigation use
and livestock use.
Water quality classification for 2005
|
Indicator
|
Ecosystem
|
Drinking Water
|
Irrigation
|
Livestock
|
|
|
NA
|
Poor
|
NA
|
NA
|
|
|
NA
|
Good
|
NA
|
NA
|
|
|
Poor
|
NA
|
NA
|
NA
|
|
|
Poor
|
NA
|
Good
|
NA
|
|
|
Good
|
NA
|
Good
|
NA
|
|
|
Good
|
Good
|
Good
|
Good
|
| Salinity |
NA
|
Poor
|
NA
|
Good
|
NA = not applicable
For the freshwater ecosystems, the groundwater is poor because
of its high nitrogen concentration, which is most likely due to
inappropriate agricultural practices. The groundwater is classified
as poor for drinking due to high salinity. This is largely due
to excess irrigation water leaching salts from the soil.
In terms of drinking water quality, the groundwater in the Padthaway
region is poor because of elevated nitrate. Nitrate can cause
methaemoglobinaemia (Blue Baby Syndrome) in young infants. The
South Australian
Department of Health recommends that groundwater users in
the South East should have bore water tested for nitrate if they
intend to use it as drinking water. The Australian
Drinking Water Guidelines recommend a guideline value of 50
mg-nitrate/L to protect bottle-fed infants under 3 months of age.
Up to 100 mg-nitrate/L can be safely consumed by adults and children
over 3 months of age.
Drinking water quality is also classified as poor because the
salinity is around 1400 -1600 mg/L, which is above the NH&MRC
guideline (for taste) of 500mg/L.
Overall, the groundwater quality in the Padthaway area is considered
good for irrigation and livestock.
Pesticides in groundwater
Groundwater samples are collected annually and analysed for a
variety of pesticides that may be leached into the unconfined
aquifer as a result of past or present agricultural practices.
Pesticides analysed in groundwater samples include several herbicides,
fungicides and insecticides. >>
More
If pesticides are detected in an aquifer system, the environmental
values of the aquifer are compromised. Therefore, the detection
of any pesticides in groundwater is considered significant and
warrants further assessment and or management response.
The results of groundwater pesticide monitoring in the Padthaway
area
|
Year
|
1998
|
1999
|
2000
|
2001
|
2002
|
2003
|
2004
|
2005
|
|
Have pesticides been detected?
|
No
|
No
|
No
|
No
|
No
|
NS
|
NS
|
No
|
NS = not sampled
>> Archived results
Download graphs
Download raw water quality data
What is being done to improve groundwater
quality
The EPA is responding to the groundwater issues in the South
East in several ways. The EPA has a regional office in Mount Gambier.
One of the roles of this office is to manage and regulate groundwater
pollution. Along with monitoring programs targeting regional groundwater
and Blue Lake, work includes:
- groundwater monitoring programs for licensees with potential
to pollute groundwater
- a risk assessment of groundwater contamination due to historical
and current copper-chrome-arsenate timber treatment plants
- a risk assessment of pollution threats to Blue Lake as a joint
Government and CSIRO research project
- development of a Code of practice for regional stormwater
disposal
The EPA works with regional management boards, community and
industry to increase awareness of groundwater quality problems
and develop management strategies. There are close links between
groundwater quantity, quality and supply in the South East. The
EPA is working with the Department
of Water, Land and Biodiversity Conservation to understand
the flow patterns around and into the Blue Lake. This work will
feed into a risk assessment of the lake.
This page was last modified 24-07-2007
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