September 2010 ISSN: 1835-954X Report No. WA 10/06 Water Assessment Water Quality Report Series Water Quality Assessment for the Ringarooma Catchment Water Assessment Branch Water and Marine Resources Division Department of Primary Industries, Parks, Water and Environment
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September 2010
ISSN: 1835-954X
Report No. WA 10/06
Water Assessment Water Quality Report Series
Water Quality Assessment for the Ringarooma Catchment
W ater As s ess m ent B r anc h
W ate r and Ma r i ne Res ou r c es D i v i s i on
Depa r tm en t o f P r im a r y I ndus t r i e s , Pa rk s , W ate r and Env i r onm en t
i
Copyright Notice:
Material contained in the report provided is subject to Australian copyright law. Other than in
accordance with the Copyright Act 1968 of the Commonwealth Parliament, no part of this report may,
in any form or by any means, be reproduced, transmitted or used. This report cannot be redistributed
for any commercial purpose whatsoever, or distributed to a third party for such purpose, without
prior written permission being sought from the Department of Primary Industries, Parks, Water and
Environment, on behalf of the Crown in Right of the State of Tasmania.
Disclaimer:
Whilst DPIPWE has made every attempt to ensure the accuracy and reliability of the information and
data provided, it is the responsibility of the data user to make their own decisions about the accuracy,
currency, reliability and correctness of information provided. The Department of Primary Industries,
Parks, Water and Environment, its employees and agents, and the Crown in the Right of the State of
Tasmania do not accept any liability for any damage caused by, or economic loss arising from, reliance
on this information.
Prepared By:
Kate Hoyle, Tom Krasnicki, Bryce Graham and Martin Read
Preferred Citation:
DPIPWE (2010). Water Quality Assessment for the Ringarooma Catchment. Water Assessment Water
Quality Report Series, Report No. WA 10/06. Water and Marine Resources Division. Department of
Primary Industries, Parks, Water and Environment, Hobart.
Contact Details:
Department of Primary Industries, Parks, Water and Environment
The Northern Natural Resource Management Region (NRM North and associated groups)
have collected physico-chemical water quality data at a range of sites within the Ringarooma
catchment since 2005 as part of AUSRIVAS river health and water quality monitoring
activities (NRM North 2005; 2006; 2007; and 2008). Most of these sites coincide with
DPIPWE AUSRIVAS sites and as such they are not mapped separately in Figure 1.
2.1.6 Mineral Resources Tasmania
Mineral Resources Tasmania conducted a statewide reconnaissance survey of acid drainage
potential from abandoned mine sites in 2000/2001 (Gurung, 2001). This survey focussed on
water chemistry, host rock geochemistry and the deposit history of abandoned mine sites,
and included an assessment of the Ringarooma catchment due to the history of tin mining in
4
the area. Results are summarised in Section 4.3, and further details (including site locations)
are available in Gurung (2001).
2.2 Water quality trigger values for the Ringarooma catchment
One way of assessing water quality condition is to compare data with appropriate “trigger”
values, following the approach recommended by the Australian and New Zealand Guidelines
for Fresh and Marine Water Quality (ANZECC 2000). A trigger value is broadly defined as a
concentration (or range) that, if exceeded, alerts water managers to a potential change and
thus “triggers” a management response. Trigger values are not designed as threshold values;
rather, they are designed to be used in conjunction with professional judgement to provide
an initial assessment of a water body (ANZECC 2000).
Trigger values that are based on reference (i.e. largely undisturbed) conditions may be
termed low-risk trigger values, meaning that below these levels there is a low risk that
adverse ecological effects will occur. If these triggers are exceeded for a sustained period, a
potential environmental problem is indicated. ANZECC (2000) recommends that trigger
values should be developed using local reference data, but also provides a set of regional
“default” low-risk trigger values for situations where there is insufficient local reference data
available for undisturbed (or slightly disturbed) rivers. ANZECC (2000) provides default low-
risk trigger values for both lowland (<150m altitude) and upland rivers (>150m altitude),
however due to Tasmania’s mountainous topography and relatively small catchment sizes,
DPIPWE generally applies the most stringent set of trigger values (those for upland rivers) to
assist the assessment of Tasmania’s rivers.
DPIPWE has also developed a set of site-specific trigger values for the Ringarooma River at
Moorina (site 30.2) monitoring site, based on monthly monitoring data collected between
2003 and 2006 (DPIW, 2008). These trigger values are based on the 80th percentile value or
20th-80th percentile range for each parameter in this dataset. The site-specific trigger values
simply enable an assessment of potential change in the river since the 2003-2006 period,
recognising that existing water quality at this site may already be influenced by varying
degrees of impact. These site-specific trigger values should not be used to determine
ecological risk, but simply provide a benchmark of condition in 2003-2006 against which
future data may be compared. The trigger values indicate an expected range during day-
time, baseflow conditions. DPIW (2008) provides further information about the
interpretation of the site-specific trigger values and this report is available through the
DPIPWE website.
The ANZECC (2000) default low-risk trigger values for slightly disturbed rivers in Tasmania
and the DPIPWE site-specific trigger values for Ringarooma River at Moorina are provided in
Table 1.
Note that ANZECC provides a trigger value for NOx (nitrate plus nitrite), whilst DPIPWE
analyses these parameters separately and thus provides a trigger value for each. DPIW
(2008) also provides additional site-specific trigger values for temperature and dissolved
oxygen (mg/L).
5
Table 1. ANZECC (2000) default low-risk trigger values for slightly disturbed ecosystems in Tasmania and DPIW (2008) site-specific trigger values for Ringarooma River at Moorina.
(a) Physico-chemical indicators: water temperature (Temp); electrical conductivity (EC); turbidity,
pH, dissolved oxygen (DO; % sat = % saturation)
Temp (
oC)
EC
(S/cm)
Turbidity (NTU)
pH DO (mg/L)
DO (% sat)
Site-specific trigger value
8-16 67-74 4 6.1-6.9 9.5-11.3 93-100
ANZECC low-risk trigger value
- 30-350 2-25 6.5-7.5* - 90-110
* values for humic rich Tasmanian rivers are 4.0-6.5
Metals have not been sampled by DPIPWE in the Ringarooma catchment since the 1990s.
These results, and those of Gurung (2001), are discussed in Section 4.
Table 2. Minimum, median and maximum results (all samples, 2003-2010) and annual median results (2004-2010) for water quality monitoring at Ringarooma River at Moorina. Median values exceeding the DPIW (2008) site-specific trigger value for this site are shaded yellow (note: 2007-2009 only, as 2003-2006 data was used to develop the trigger value); median values exceeding the ANZECC (2000) default low-risk trigger value are shaded orange (note: NO3 median values greater than the ANZECC trigger value for NOx were highlighted as exceedances, as NOx = NO3 + NO2); no median values exceed both trigger values.
(a) Physico-chemical indicators: water temperature (Temp); electrical conductivity (EC); turbidity, pH, dissolved oxygen (DO; % sat = % saturation)
Parameter Temp EC Turbidity DO DO pH
°C µS/cm NTU mg/L % sat
Minimum (2003-2010) 3.5 58.2 1.20 7.04 76.8 5.46
Median (2003-2010) 11.6 71.4 2.62 10.60 98.0 6.68
Maximum (2003-2010) 23.3 89.2 36.7 14.10 118.1 7.58
data, Appendix 4), suggests that electrical conductivity generally increases down the length
of the main Ringarooma River, but that levels in certain tributaries in the upper catchment
(e.g. Legerwood Rivulet, Dorset River) may also be slightly higher. Nevertheless, conductivity
across the catchment is very low.
Turbidity levels at the three monitoring sites are also very low with most results <5 NTU, and
there is no apparent temporal trend (Figure 2d). Higher results generally occur during winter
and are naturally associated with higher flows, with the high values recorded at Ringarooma
at Moorina in the winter of 2007 and 2008 being a result of routine sampling occurring
during the rise or fall of flood events. Like conductivity, higher baseflow turbidities have
been recorded in Legerwood Rivulet (Appendices 2a and 3a) and in the lower Ringarooma
River at TEFlows site RR1 (Appendix 4), however levels across the catchment are still below
10 NTU.
9
Dissolved oxygen levels are healthy at all monitoring sites and show no apparent temporal
trend (Figure 2e & f). A natural seasonal cycle is evident in the dissolved oxygen (mg/L) data
at Ringarooma at Moorina, which is associated with the capacity for cooler water to hold
more oxygen. A noticeable low value in March 2007 was most likely associated with
temporary high temperatures and lower flows at the time of sampling.
No obvious temporal or spatial trends are evident for pH at the long term monitoring sites
(Figure 2g). pH values across the catchment tend to be slightly acidic to neutral, as discussed
in Section 3.1 (see also Appendices 2 and 3).
Results for total nitrogen, nitrate and ammonia indicate that although levels at Ringarooma
at Moorina are elevated (see Section 3.1), with some particularly high levels associated with
flood events, a potential slight decreasing trend is evident since 2003 (Figure 2 h, i & k).
Higher values tend to occur in the winter-spring season and are associated with higher
baseflows and increased runoff. Most recent samples show some higher values were
recorded in the winter of 2009, but because nutrient sampling ceased in July 2009 it is not
possible to determine whether these were simply related to higher flows or whether levels
would have stabilised under lower baseflows. As noted in Section 3.1, sustained high nitrate
levels (combined with high phosphorus) may increase the potential for eutrophication-
related impacts (such as excess primary production, depleted oxygen and algal blooms)
under susceptible conditions (generally low flows and higher temperatures). Note that such
impacts have not been observed at Ringarooma River monitoring locations. Nitrite results
are consistently low (Figure 2j); this form of nitrogen is generally short-lived in the
environment as it is quickly converted to nitrate by bacteria.
It appears that higher concentrations of nitrogen parameters may be present in the upper
catchment, as indicated by noticeably lower levels at the lower catchment TEFlows site RR1.
While there are not enough samples to determine whether this is a definite pattern, it
reflects similar findings in the 1998 State of Rivers report for the catchment (Bobbi et al.,
1999a; see Section 4.2). Bobbi et al., (1999a) attributed these findings to land use in the
middle and upper part of the catchment, which contains the most productive land and more
intensive agricultural activity.
Current total phosphorus levels at Ringarooma at Moorina are generally low, and appear to
have reduced somewhat since the earlier years of the BWQMP. As for nitrogen, higher levels
are associated with high-flow events (Figure 2l). During baseflow conditions, many individual
samples slightly exceed or approach the ANZECC (2000) low-risk trigger value for this
parameter (0.013 mg/L), but median values have not exceeded this trigger since 2004
(Section 3.1). Dissolved phosphorus levels have generally remained low (Figure 2m).
Interestingly, total phosphorus levels were higher in the lower catchment (RR1) during the
TEFlows study, which is the opposite pattern to that observed for nitrogen parameters.
Phosphorus binds readily to particulate material in waterways, and the higher phosphorus
results in the lower catchment may be related to the higher turbidity levels at this
downstream site.
The reason for the observed potential decrease in some nutrient parameters over the 2003-
2009 period would require a more comprehensive investigation of site and catchment
conditions, which is outside the scope of this report. In general terms, possible explanations
10
for nutrient reductions could include: improved land use practices in the catchment; change
of land use; additional or improved riparian vegetation, which both increases nutrient
uptake and acts as a buffer to runoff (either at the sampling location or upstream); and/or
reduced nutrient-loaded surface runoff (related to reduced rainfall and/or improved
irrigation practices). It is considered unlikely that the observed potential decrease in
nutrients is related to sampling time at this location.
Figure 2. Daily stream flow (a) for Ringarooma River at Moorina, and water quality sampling results for Ringarooma River at Moorina and other sites within the Ringarooma catchment: (b) water temperature; (c) electrical conductivity.
0
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Ringarooma at Moorina aggregate daily stream flow
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Ringarooma u/s Branxholm
Dorset at Ruby Flats Rd
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(a)
(b)
(c)
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Figure 2 cont. Water quality sampling results for Ringarooma River at Moorina and other sites
within the Ringarooma catchment: (d) turbidity; (e) dissolved oxygen mg/L; (f) dissolved oxygen %
saturation; (g) pH.
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TU)
Ringarooma at Moorina
Ringarooma u/s Branxholm
Dorset at Ruby Flats Rd
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(%
sat
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4.5
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8.5
9
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pH
(d)
(f)
(e)
(g)
12
Figure 2 cont. Water quality sampling results for Ringarooma River at Moorina and other sites
within the Ringarooma catchment: (h) total nitrogen; (i) nitrate as N; (j) nitrite as N; (k) ammonia as
N.
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1.5
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2.5
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Tota
l nit
roge
n (
mg/
L)
Ringarooma at Moorina
TEFlows RR1
TEFlows RR2
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0.8
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rate
(mg/
L)
0
0.0005
0.001
0.0015
0.002
0.0025
0.003
0.0035
0.004
0.0045
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03
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rite
(mg/
L)
Values at 0 = below detectable limit (<0.002 mg/L)
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0.01
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Jul-
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Am
mo
nia
(m
g/L)
(h)
(i)
(j)
(k)
13
Figure 2 cont. Water quality sampling results for Ringarooma River at Moorina and other sites
within the Ringarooma catchment: (l) total phosphorus; (m) dissolved reactive phosphorus as P.
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Tota
l ph
osp
ho
rus
(mg/
L)
Ringarooma at Moorina
TEFlows RR1
TEFlows RR2
Values at 0 = below detectable limit (<0.005 mg/L)
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0.001
0.002
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solv
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acti
ve p
ho
sph
oru
s (m
g/L)
Values at 0 = below detectable limit (<0.002 mg/L)
(l)
(m)
14
3.3 Summary of continuous monitoring data
Continuous monitoring data is useful for providing more detailed information about daily
and seasonal cycles, and for examining relationships between water quality parameters and
flow. Plots of continuous water quality data and flow are provided in Figure 3. For the
purpose of graphical presentation, continuous (15-minute) data has been aggregated on a 2-
hourly time-step for temperature and an hourly time-step for electrical conductivity and
turbidity. Due to the poor quality of the data record for electrical conductivity and turbidity
(as discussed in Section 2.1.1), only selected periods of data are displayed to show the
typical response of these parameters to flow. Continuous data is available on WIST
(www.water.dpiw.tas.gov.au/wist/ui).
As reflected by the monthly sampling, continuous water temperature at Ringarooma at
Moorina shows a strong seasonal cycle with temperatures generally ranging between 5-25°C
(Figure 3a). Diurnal variation in temperature is greater during the summer months. Gaps in
the data record are due to instrument malfunction or poor data quality.
Electrical conductivity remained very low (<100 µS/cm) throughout 2006 (Figure 3b). Levels
during summer are generally slightly higher, although the difference between seasons is
relatively small. This seasonal pattern is most likely associated with lower baseflows and
greater groundwater contribution to overall flow during summer, a cycle that is common in
many rivers in Tasmania. Substantial drops in conductivity coincide with peaks in stream
flow, another common pattern which is caused by the addition of a large amount of
freshwater to the river during rainfall events. In some rivers this drop is preceded by a short
peak in conductivity when initial surface runoff mobilises dissolved salts, but this is not
evident in the data for Ringarooma River at Moorina, possibly indicating low salt levels the
soils and underlying geology of the catchment. Note that the continuous electrical
conductivity data presented in the original report by Meyer (2005) included continuous data
for 2004, which showed a marked seasonal cycle of higher levels during winter, the opposite
pattern to that displayed in subsequent years. This pattern was also not reflected in monthly
sampling during 2004. With this additional information, revision of the continuous data for
2004 suggests that this seasonal signal was false, most likely caused by an issue with
temperature compensation by the sensor or during data processing (electrical conductivity is
influenced by temperature, and is it conventional practice to “compensate” EC data by
standardising it to a temperature reference of 25°C).
Continuous turbidity data for Ringarooma River at Moorina from November 2008 to July
2009 (Figure 3c) reflects the monthly results, showing low turbidity levels during baseflows.
Peaks in turbidity correspond with flood events, and are due to runoff of soil and particulate
matter during and following high rainfall. The data provided in Figure 3c indicates that
during significant flood events, turbidity may peak at between 50-100x greater than
baseflow levels. During the November 2008 – July 2009 period, turbidity levels approached
100 NTU for most major flow events and ~200 NTU for the event in July 2009. Turbidity
levels during flood events do not just depend on the size of the event, but are influenced by
factors including the previous flow regime and conditions in the catchment at the time of
Figure 3. Continuous water quality monitoring data for the Ringarooma River at Moorina: (a) water temperature (aggregated 2-hourly); (b) electrical conductivity (aggregated hourly); (c) turbidity (aggregated hourly). Note time periods do not align.
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(c)
16
4 Summary of historical water quality data within the Ringarooma
catchment
4.1 Historic AUSRIVAS monitoring
In addition to the two long term AUSRIVAS monitoring sites, water quality data has been
collected at 42 additional AUSRIVAS sites around the Ringarooma catchment on a sporadic
and generally infrequent basis between 1994-2008. A large proportion of these sites were
only sampled during more extensive catchment surveys in 1994 and/or 1998. Nevertheless,
these results provide an indication of the range of values that have been recorded across the
Ringarooma catchment historically. The pooled results (all 44 sites) of AUSRIVAS sampling
are summarised in Table 3 (historic data, recent data and all data combined), and the full
dataset provided in Appendix 2a. Median results across time periods are generally very
similar.
Electrical conductivity has been very low across the catchment (medians <70 µS/cm).
Highest recorded values were a single sample at Davids Creek above Gladstone Rd in 1998
(173.8 µS/cm) and samples around 110 µS/cm in Legerwood Rivulet (both in the 1990s and
2007/2008).
Turbidity was also very low with the majority of sites recording below 5 NTU. A median of
5.67 NTU was recorded for Legerwood Rivulet. Again some of the highest recorded values
were a single sample at Davids Creek above Gladstone Rd in 1998 (15.3 NTU) and samples
around 5-7 NTU in Legerwood Rivulet (both in the 1990s and 2007/2008).
Dissolved oxygen concentrations were very good throughout the catchment with a median
of around 10.0 mg/L for all time periods. Historically, individual low values were recorded in
the New River at New River Rd (4.32 mg/L in 1995) and the Cascade River off the Tasman
Highway (5.4 mg/L in 1998).
Waters throughout the Ringarooma catchment ranged from slightly acidic to neutral. Some
of the more acidic rivers were Dunns Creek and the New River in the upper catchment.
Table 3. AUSRIVAS water quality monitoring data summary, pooled sites. Temp = water temperature; EC = electrical conductivity; DO = dissolved oxygen.
Parameter Temp EC Turbidity DO DO pH
Time period Statistic °C µS/cm NTU mg/L % sat
1994-2003
Minimum 6.3 28.8 0.25 4.32 n/a 5.0
Median 13.0 59.0 2.22 9.8 n/a 6.19
Maximum 24.1 173.8 15.3 12.05 n/a 7.81
No. samples 91 87 91 73 0 91
2004-2010
Minimum 6.1 34.8 0.45 8.77 83.4 5.5
Median 12.0 67.0 2.08 10.16 96.7 6.72
Maximum 19.7 108.2 7.54 11.58 110 7.53
No. samples 36 36 36 36 36 36
1994-2010
Minimum 6.1 28.8 0.25 4.32 83.4 5.0
Median 12.3 62.7 2.11 10.0 96.7 6.41
Maximum 24.1 173.8 15.3 12.05 110 7.81
No. samples 127 123 127 109 36 127
17
During 1994 and 1995, AUSRIVAS monitoring included sampling for four heavy metals
(cadmium, copper, lead and zinc) at five upper-mid catchment sites in the Ringarooma
catchment (Appendix 2b). The majority of samples returned results below laboratory
detection limits. One sample from Dunns Creek off Maurice Rd in Spring 1995 returned a
result of 2 µg/L for copper and 9 µg/L for zinc. These values are slightly higher than the
subsequently developed ANZECC (2000) toxicant trigger values for 95 % protection of
species for copper (1.4 µg/L) and zinc (8.0 µg/L). The New River at New River Rd returned a
result of 7 µg/L for zinc in Spring 1995, and an incidental sample taken from the Ringarooma
River u/s of Maurice River in Autumn 1996 was analysed for zinc and returned a value of 14
µg/L. Note that laboratory detection limits improved in 1995, and prior to this detection
limits were higher than the ANZECC (2000) triggers which are applied today. Furthermore,
the toxicity of metals can vary according to the form they are present in (i.e. dissolved or
bound to other substances) and environmental conditions (e.g. pH). Additional testing would
have been required to determine whether detected levels posed any environmental risk.
Metals in the Ringarooma catchment were assessed more comprehensively by DPIPWE
during the 1998 State of Rivers survey, and by Mineral Resources Tasmania in 2000/2001
(Gurung, 2001), the findings of which are summarised in the following sections.
Nutrient samples were also collected at the same five sites during AUSRIVAS monitoring
between 1994 and 1998 (Appendix 2b). As with recent sampling, these results showed
moderately elevated levels of total nitrogen and nitrate at most sites, with highest levels at
Ringarooma at Branxholm. Relatively low levels were recorded at Dunns Creek off Maurice
Rd, which has a much smaller receiving catchment area.
4.2 State of River reporting for Ringarooma catchment
A one year study looking at water quality, hydrology, aquatic ecology and river condition in
the Ringarooma catchment was conducted during 1998 (Bobbi et al., 1999a). These
investigations were reported as a ‘State of River” report, completed in 1999. The report
found that many of the water quality parameters measured indicated that the quality of the
water in the Ringarooma catchment was very good in 1998.
Two potential water quality issues were identified in the catchment at that time. The first
was related to elevated nutrient and faecal coliform levels in the middle part of the
catchment (between Ringarooma and Derby) and associated tributaries (Legerwood Rivulet,
Dorset River and New River). Further detail is provided below.
The second issue raised by Bobbi et al. (1999a) related to high dissolved aluminium
concentrations detected in the Wyniford River, which may pose some risk to environmental
health. The concentration of other analysed metals was generally found to be minor or
below laboratory limits of detection (Bobbi et al.,1999a), although some higher zinc levels
were detected during summer at sites on the Ringarooma River and Legerwood Rivulet.
Elevated levels of metals including aluminium and zinc have been detected in other
catchments in the region (e.g. Great Forester; Bobbi et al., 1999b). It was suggested that
these results may be indicative of the granite geology underlying much of the catchment and
18
represent naturally occurring background levels in rivers throughout the region (Bobbi et al.,
1999b). The presence of metals in some parts of the Ringarooma catchment is also likely to
be further influenced by the history of tin mining in the catchment, as discussed in Section
4.3.
A summary of the main water quality findings from the 1998 State of Rivers report is
provided below (extracted from Bobbi et al.,1999):
Rivers throughout the catchment are acidic, with average pH at all sites between 5.4
and 6.5. Of the 10 sites monitored on a monthly basis, the New River was most acidic,
with a minimum pH reading of 4.88.
Dissolved oxygen concentrations, which are a good indicator of ecological health, were
largely reflective of a healthy river system. Lowest concentrations were measured in the
New River during summer, when dissolved oxygen levels are depleted and may cause
stress to fish and other aquatic life.
Ambient baseflow turbidity levels at all sites was good, although there was a gradual
increase in turbidity towards the lower reaches of the Ringarooma River. Higher
turbidity was recorded during periods following rainfall events, when runoff caused
increases of 200-400% in the Ringarooma River.
Conductivity at all sites was very low and indicative of waters that are low in dissolved
salts such as sodium, magnesium, calcium and chloride. Water throughout the
catchment can be classified as very ‘soft’.
Nitrate nitrogen concentrations were highest in the tributaries draining the middle of
the catchment (between Ringarooma and Derby) and may be responsible for increased
concentrations in the Ringarooma River at Long Bridge and Moorina. Higher
concentrations at most sites corresponded with higher baseflows between July and
October.
Snapshot surveys of nitrogen across 23 sites in the catchment highlighted Legerwood
Rivulet, the New River and the Dorset River as having highest concentrations, while
lowest levels were recorded in the Maurice, Weld and Wyniford rivers.
Results from tests for ammonia nitrogen show that sites in the middle and upper
catchments may be showing the impact from intensive animal industries in the area.
Together with other nutrient data, it appears that the majority of nutrient input to the
Ringarooma River is from tributaries draining the middle section of the catchment.
Legerwood Rivulet was highlighted as one tributary which has elevated nutrient
concentrations.
Snapshot surveys of E. coli at sites throughout the catchment showed that waterways in
the upper and middle section of the catchment are most affected by faecal pollution,
reflecting the intensity of animal based agriculture in that area. Levels of bacteria were
greatest in summer when elevated water temperature increases the lifetime of faecal
coliforms in the environment.
While most sites showed heavy metal concentrations at or below limits of detection
through analysis, significant results for aluminium were obtained from Legerwood
Rivulet, the Wyniford River and the Weld River. In the Wyniford River it is present in
dissolved form and further testing is needed to determine its impact on aquatic life.
19
During significant flooding on September 23rd (1998), turbidity at several sites in the
Ringarooma River was 100 times greater than baseflow conditions, while nutrient
concentrations were up to 10 times greater. At Moorina, instantaneous loads of
nitrogen and phosphorus being transported down river were calculated at 1,666 kg/hr
and 346 kg/hr respectively.
Export yields at Moorina, corrected for catchment size, were estimated at 431 kg/hr of
suspended solids, 2.75 kg/hr of nitrogen and 0.57 kg/hr of phosphorus.
4.3 Mineral Resources Tasmania acid drainage survey
A survey of acid drainage conducted by Mineral Resources Tasmania identified nine historic
mining sites in the lower Ringarooma catchment with the potential to produce acid drainage
(Gurung, 2001). Acid drainage is defined by Gurung (2001) as “low pH-high metal and high
sulphate-bearing waters, formed when rocks and sediments containing sulphide minerals
are exposed to the atmosphere under an oxidising environment”. Mining activities can
expose large quantities of rock, sediment and tailings rich in sulphide minerals, which under
the right conditions may result in the runoff of acid drainage into waterways. Acid drainage
can also mobilise heavy metals present in the host rock/sediment, with subsequent release
to surface waters and stream sediments proximal to mine sites. At the time of the survey,
three main sites producing acid drainage were identified within the lower Ringarooma
catchment: the Endurance, Monarch and Star Hill tin mine sites (note that the Monarch
mine site is located in the adjacent Boobyalla catchment, which has not been assessed in
this report). In particular, the Endurance mine site discharged acid drainage into Ruby Creek,
and water chemistry analyses identified some very high levels of metals including aluminium
and iron (Gurung, 2001). Ruby Creek discharges into the Ringarooma River, where the
influence of higher-pH water is likely to considerably reduce the levels of metals in solution.
Nevertheless this represents a potential source of ecological risk, and Gurung (2001)
identified that many streams (and stream sediments) close to and/or downstream of historic
mining areas within the Ringarooma catchment may be impacted by mine tailings. Gurung
(2001) also noted that remediation programs were being implemented at that time.
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5 Summary
Physico-chemical data available for the Ringarooma catchment indicate that the quality of
the water in the catchment is generally good. The Ringarooma River is characterised by
healthy temperature and dissolved oxygen ranges, low electrical conductivity (indicating low
dissolved salts), low turbidity (indicating low suspended solids) and slightly acidic to neutral
pH. Monthly data collected at Ringarooma River at Moorina during 2003-2010 has not
revealed any discernible trends in these physico-chemical parameters over this period.
Both recent and historic samples have detected elevated levels of some nutrient
parameters, particularly nitrate, in the Ringarooma catchment. State of Rivers sampling
(Bobbi et al., 1999a) suggested that concentrations of nitrogen parameters appear to be
most elevated in the upper and middle catchment, most likely related to more intensive
agricultural land use in this region. Recent sampling by the TEFlows Project also found that
total nitrogen and nitrate levels were higher in the upper catchment. Monthly sampling at
Ringarooma River at Moorina indicates that there has been a potential decreasing trend in
the levels of several nutrient parameters at this location over the 2003-2009 period.
Historic sampling for heavy metals indicated that levels were generally considered low or
not significant across the majority of sites in the Ringarooma catchment (Bobbi et al.,
1999a). Potentially significant levels of dissolved aluminium in the Wyniford River in 1998
were identified by Bobbi et al. (1999a), although further investigation was required to
determine the potential for ecological risk. It is likely that elevated background levels of
some metals may be related to the granitic geology of the catchment. However, several
areas in the lower Ringarooma catchment have been identified by Gurung (2001) as being
impacted by acid drainage, with associated very high levels of some metals. This is
predominantly due to historic tin mining in the area, in combination with the geological
characteristics of the region.
The main purpose of this document is to provide background information to the
development of a water management plan for the Ringarooma catchment. On this basis, it is
worth noting that elevated levels of nutrients or metals are primarily related to surrounding
catchment characteristics and/or land use factors, rather than potential changes in flow
regime arising from water allocation in the catchment.
21
6 References
ANZECC (2000). Australian and New Zealand Guidelines for Fresh and Marine Water Quality. National Water Quality Management Strategy Paper No. 4, Volume 1, The Guidelines. Australian and New Zealand Environment and Conservation Council; and Agriculture and Resource Management Council of Australia and New Zealand.
Bobbi, C., Graham, B., Nelson, M. and Read, M. (1999a). State of River Report for Rivers in the Ringarooma Catchment. Report Series WRA 99/01 – 04. Department of Primary Industries, Water and Environment, Tasmania.
Bobbi, C., Nelson, M., Krasnicki, T. and Graham, B. (1999b). State of River Report for Rivers in the Great Forester Catchment. Report Series WRA 99/05 – 08. Department of Primary Industries, Water and Environment, Tasmania.
DPIW (2008). Site-specific trigger values for physico-chemical indicators monitored under the DPIW Baseline Water Quality Monitoring Program. Water Assessment Water Quality Report Series, Report No. WA 08/52. Water Resources Division. Department of Primary Industries and Water, Tasmania.
DPIPWE (2010). Tasmanian Environmental Flows (TEFlows) Project Technical Report. Water Assessment Aquatic Ecology Report Series, Report No. WA 09/10. Water and Marine Resources Division. Department of Primary Industries, Parks, Water and Environment, Tasmania.
Goudey, R. (1999). Assessing Water Quality Objectives: Discussion Paper. Environment Protection Authority, State of Victoria.
Gurung, S. (2001). Tasmanian Acid Drainage Reconnaissance. Report 1 Acid drainage from abandoned mines in Tasmania. Tasmanian Geological Survey Record 2001/05. Mineral Resources Tasmania.
Meyer, S. (2005). Ringarooma Catchment Water Quality Monitoring. Internal Report to the Water Resources Division, Department of Primary Industries, Water and Environment, Tasmania.
NRM North (2005). State of the Region: water quality and stream condition in Northern Tasmania. NRM North Water Monitoring Team in partnership with the Launceston Environment Centre, Tasmania.
NRM North (2006). State of the Region: water quality and stream condition in Northern Tasmania. NRM North Water Monitoring Team in partnership with the Launceston Environment Centre, Tasmania.
NRM North (2007). State of the Region: water quality and stream condition in Northern Tasmania. NRM North Water Monitoring Team in partnership with the Launceston Environment Centre, Tasmania.
NRM North (2008). State of the Region: water quality and stream condition in Northern Tasmania. NRM North Water Monitoring Team in partnership with the Launceston Environment Centre, Tasmania.
22
Appendix 1 - Monthly BWQMP sampling results for the Ringarooma River at Moorina (site 30.2)
Date and Time Temperature (° C)
Electrical Conductivity (µS/cm)
Turbidity (NTU)
Dissolved Oxygen (mg/L)
Dissolved Oxygen (% saturation)
pH
Ammonia (mg-N/L)
Nitrate (mg-N/L)
Nitrite (mg-N/L)
Dissolved Reactive Phosphorus (mg-P/L)
Total Nitrogen (mg/L)
Total Phosphorus (mg/L)
16/09/2003 NA 71 7.59 NA NA 6.44 0.013 0.63 0.002 0.005 0.9 0.016
Appendix 3b – NRM NORTH Water Quality Monitoring results (2005 – 2007)
Summary results of water monitoring conducted in the Ringarooma catchment by NRM North and Northern Waterwatch volunteers. Data sourced from NRM North State of the Region Reports (NRM North 2005, 2006 and 2007).
Minimum Median Maximum No. Of Samples
Ringarooma River at Bells Bridge, 2005. Monitored by NRM North
Temperature (oC) 8.1 13.9 22.7 11
Turbidity (NTU) 1.14 8.78 21.28 10
Electrical Conductivity (μS/cm) 66.0 80.0 91.3 11
Field pH 6.27 6.30 6.96 10
Ringarooma River at Pioneer, 2005. Monitored by Northern Waterwatch
Temperature (oC) 7.1 14.6 22.5 12
Turbidity (NTU) <7 <7 <7 12
Electrical Conductivity (μS/cm) 57 68.5 74 12
Wyniford River at Pioneer, 2005. Monitored by Northern Waterwatch
Temperature (oC) 7 14.3 18.1 12
Turbidity (NTU) <7 <7 <7 12
Electrical Conductivity (μS/cm) 70 75.5 91 12
Ringarooma River at Tebrakunnah Road, 2006. Monitored by Northern Waterwatch
Temperature (oC) 7.1 16.6 22.5 14
Turbidity (NTU) <7 <7 <7 14
Electrical Conductivity (μS/cm) 57 69 75 14
Ringarooma River at Bells Bridge, 2006. Monitored by NRM North
Turbidity (NTU) 2 5 12 11
Electrical Conductivity (μS/cm) 67 77 84 11
Wyniford River at Tebrakunnah Road, 2006. Monitored by Northern Waterwatch
Temperature (oC) 7.0 15.3 18.2 14
Turbidity (NTU) <7 <7 <7 14
Electrical Conductivity (μS/cm) 70 75 95 14
Ringarooma River above Long Bridge, 2006. Monitored by Northern Waterwatch
Temperature (oC) 8.5 13.6 15.4 10
Turbidity (NTU) <7 <7 15 8
Electrical Conductivity (μS/cm) 56 64 72 10
Ringarooma River at Branxholm, 2006. Monitored by Northern Waterwatch
Temperature (oC) 7.2 11.1 20.2 7
Turbidity (NTU) <7 <7 <7 15
Electrical Conductivity (μS/cm) 49 60 103 15
Ringarooma River at Bells Bridge, 2007. Monitored by Northern Waterwatch
Turbidity (NTU) 0 not provided 16.67 12
Electrical Conductivity (μS/cm) 64.1 not provided 119.8 12
31
Appendix 4 – Results of TEFlows Project water quality monitoring in the Ringarooma catchment.
Site Date Temperature (° C)
pH Electrical Conductivity (µS/cm)
Turbidity (NTU)
Dissolved Oxygen (mg/L)
Dissolved Oxygen (% saturation)
Total Nitrogen (mg/L)
Total Phosphorus (mg/L)
Dissolved Reactive Phosphorus (mg-P/L)
Nitrate (mg-N/L)
Nitrite (mg-N/L)
Ammonia (mg-N/L)
RR1 31/07/2007 7.9 6.4 104 6.98 11.4 96.4 0.6 0.016 NA NA NA NA
RR1 30/10/2007 17.8 6.82 84 7.93 8.59 91.1 0.48 0.013 NA NA NA NA
RR1 12/02/2008 18.8 6.83 106 3.44 8.11 87 0.32 0.009 NA NA NA NA
RR1 12/08/2008 7.7 6.62 108 7.35 10.99 92 0.49 0.02 NA NA NA NA
RR1 6/11/2008 14.4 6.84 99 2.27 9.5 93.3 0.07 <0.005 NA NA NA NA
RR2 29/08/2007 9.2 7.22 67 2.91 11.7 100.9 1.1 0.01 NA NA NA NA
RR2 1/11/2007 10.4 6.62 54 1.62 10.8 93 0.7 0.009 NA NA NA NA
RR2 15/02/2008 16.7 6.75 70 0.95 9.04 92.6 0.75 0.007 NA NA NA NA