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Water Quality of Rivers in theNorth Esk Catchment

A Report Forming Part of the Requirements for State of Rivers Reporting

PART 3

Authors;Katrina Berry 1Christopher Bobbi 2Abigail Foley 1Water Assessment and Planning BranchDPIWE.

1 Water Assessment and Planning Branch, Water Resources Division.2 Environmental and Resource Analysis, Hydro Tasmania.

December 2003

ii

Copyright Notice:

Material contained in the report provided is subject to Australian copyright law. Other than inaccordance 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 redistributedfor any commercial purpose whatsoever, or distributed to a third party for such purpose, without priorwritten permission being sought from the Department of Primary Industries, Water and Environment,on behalf of the Crown in Right of the State of Tasmania.

Disclaimer:

Whilst DPIWE has made every attempt to ensure the accuracy and reliability of the information anddata 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, Water and Environment, its employees and agents, and theCrown in the Right of the State of Tasmania do not accept any liability for any damage caused by, oreconomic loss arising from, reliance on this information.

Preferred Citation:DPIWE (2003) State of Rivers Report for the North Esk Catchment. Water Assessment and PlanningBranch, Department of Primary Industries, Water and Environment, Hobart.Technical Report No. WAP 03/06

ISSN: 1449-5996

The Department of Primary Industries, Water and Environment

The Department of Primary Industries, Water and Environment provides leadership in the sustainablemanagement and development of Tasmania’s resources. The Mission of the Department is to advanceTasmania’s prosperity through the sustainable development of our natural resources and theconservation of our natural and cultural heritage for the future.

The Water Resources Division provides a focus for water management and water development inTasmania through a diverse range of functions including the design of policy and regulatoryframeworks to ensure sustainable use of the surface water and groundwater resources; monitoring,assessment and reporting on the condition of the State’s freshwater resources; facilitation ofinfrastructure development projects to ensure the efficient and sustainable supply of water; andimplementation of the Water Management Act 1999, related legislation and the State WaterDevelopment Plan.

State of Rivers Water Quality of the North Esk Catchment

44

2.4 Catchment SurveysCatchment ‘snapshots’ were carried out during stable base flows in summer (18-20 Jan, 2000) andwinter (26-28 Jul, 1999). The aim of this approach is to characterise water quality at a catchmentscale, allowing areas where relative degradation occurs to be highlighted. This approach has beenemployed in studies in mainland Australia (Grayston, et. al., 1997) and more extensively withinTasmania (Bobbi, et al., 1996; Bobbi, 1997; Bobbi, 1998) and has been a valuable tool for waterquality assessment on a catchment scale. When using this technique it is important to target stablehydrological conditions and avoid the confounding influences of rain (and runoff) which can makeinterpretation and comparison difficult leading to erroneous conclusions. While all sites werecomprehensively sampled during each survey, only those parameters which are not normallysampled during routine monthly monitoring will be discussed here. Data collected on the morecommon parameters (ie dissolved oxygen, temperature, conductivity, pH and turbidity etc) shall notbe discussed here as their seasonal variations have been discussed in more detail in section 2.1.

During the catchment snapshot of winter 1999, baseflows in the North Esk River at Ballroom(NE27) were well below average (3.85 m3/s) compared to the historical record (8.06 m3/s). Flowsduring summer snapshot monitoring in 2000 were near average (1.35 m3/s) when compared to thehistorical record (1.6m3/s). When interpreting the data set presented in this report it is important toconsider that records from the winter survey represent samples taken during lower than averagebaseline winter flows.

2.4.3 Catchment Survey – Total NitrogenThe survey data for total nitrogen (TN) shows that the winter concentrations at a majority of siteswere generally greater than those recorded during the summer survey (Figure 2.4.1). This supportsearlier conclusions from monthly sampling where higher winter TN concentrations generally resultfrom the ‘flushing’ or mobilisation of nitrates through the soil profile into surface waters.

The majority of sites had concentrations of TN near or below the suggested trigger value of 480µg/L(ANZECC, 2000) with summer and winter median TN concentrations of 362µg/L and 481 µg/Lrespectively. Data from both surveys shows that that TN concentrations throughout the North Eskcatchment are low, with only five sites recording high concentrations during both surveys (Figure2.4.1). These include urban sites such as the North Esk downstream of the confluence of KingsMeadows Rivulet (NE1), Kings Meadows Rivulet at Punchbowl (NE3) and North Esk downstreamof Norwood sewerage treatment plant (NE2) with Kings Meadows Rivulet at Punchbowl recordingthe highest concentration of 1.78µg/L during the winter survey. Only three sites in areas subjectprimarily to agricultural activities recorded high TN concentrations; two of these being Rose Rivuletabove Patersons Island (NE31) and North Esk at Burns Creek Road (NE22) both of which hadhigher winter concentrations only. Old Mill Creek at Blessington Road (NE24) recorded high TNconcentrations during both surveys, with summer concentrations greater than those in winter. Thissite is subject to prolific growth of cumbungi (Typha spp) which, during lower summer flowsincreases the rate of deposition of suspended solids to which nutrients are attached and hence leadingto higher TN concentrations.

Nitrate-Nitrogen (NO3/N) concentration was consistently higher at all sites during winter comparedto summer (Figure 2.4.2). This supports earlier comments that during the wetter winter monthsnitrates are flushed through the soil profile and into surface waters. Higher winter concentrationsmay also be a result of land clearance for cultivation and grazing. This activity aerates the soil andhas the effect of enhancing nitrifying bacteria which increases soil NO3/N (UNESCO, 1992). This ismost evident at sites in the upper catchment of the North Esk River and St Patricks River, whereNO3/N contributed approximately >50% to total nitrogen concentrations at these sites (Table 2.4.1).Kings Meadows Rivulet at Punchbowl recorded the highest NO3/N concentration of 1780µg/Lcontributing 66% of TN recorded at this site.


45

Site

NE

1N

E 2

NE

3N

E 4

NE

5N

E 6

NE

7N

E 8

NE

9N

E 10

NE

11N

E 12

NE

13N

E 14

NE

15N

E 16

NE

17N

E 18

NE

19a

NE

19b

NE

20N

E 21

NE

22N

E 23

NE

24N

E 25

NE

26N

E 27

NE

28N

E 29

NE

30N

E 31

NE

32

TN u

g/L

0

200

400

600

800

1000

1200

1400

1600

1800

2000

Winter TN Summer TN

Figure 2.4.1: Total nitrogen concentrations for winter 1999 and summer 2000 snapshot surveys forthe North Esk catchment.

Site No.

NE

1N

E 2

NE

3N

E 4

NE

5N

E 6

NE

7N

E 8

NE

9N

E 10

NE

11N

E 12

NE

13N

E 14

NE

15N

E 16

NE

17N

E 18

NE

19a

NE

19b

NE

20N

E 21

NE

22N

E 23

NE

24N

E 25

NE

26N

E 27

NE

28N

E 29

NE

30N

E 31

NE

32

Nitr

ate-

Nitr

ogen

(ug/

L)

0

200

400

600

800

1000

1200

1400

Winter NO3/N Summer NO3/N

Figure 2.4.2: Nitrate-nitrogen concentrations for winter 1999 and summer 2000 snapshot surveys forthe North Esk catchment.


46

Table 2.4.1: Selected results from top of catchment sites on the St Patricks River (NE14-NE18) andthe North Esk River (NE 19a-NE20) recorded during the summer (2000) and winter (1999) snapshotsurveys.

Summer WinterSite No Total N

µg/LNO3/N µg/L NO3/N % Total N µg/L NO3/N µg/L NO3/N %

NE 14 376 127 34 432 295 68NE 15 328 170 52 583 371 64NE 16 299 144 48 480 346 72NE 17 300 147 49 481 318 66NE 18 403 200 50 437 217 50NE 19a 364 234 64 517 377 73NE 19b 414 273 66 528 322 61NE 20 368 191 52 534 385 72

Ammonia (NH3/N) concentrations during both surveys were generally low (Figure 2.4.3), with theexception of North Esk River downstream of Norwood sewerage treatment plant (NE2) wheresummer NH3/N concentrations contributed 48% to TN and winter concentrations were 45.6% of TN.Ammonia occurs naturally in surface waters, but higher levels may be an indication of organicpollution from activities such as domestic sewerage, industrial waste and fertiliser run off(UNESCO, 1992). With the exception of NE2, winter concentrations were higher during summercompared to winter when higher flows are more likely to dilute NH3/N in surface waters.

Site No

NE

1N

E 2

NE

3N

E 4

NE

5N

E 6

NE

7N

E 8

NE

9N

E 10

NE

11N

E 12

NE

13N

E 14

NE

15N

E 16

NE

17N

E 18

NE

19a

NE

19b

NE

20N

E 21

NE

22N

E 23

NE

24N

E 25

NE

26N

E 27

NE

28N

E 29

NE

30N

E 31

NE

32

Amm

onia

(ug/

L)

0

100

200

300

400

Winter NH3/N Summer NH3/N

Figure 2.4.3: Ammonia concentrations for winter 1999 and summer 2000 snapshot surveys for theNorth Esk catchment.


47

2.4.4 Catchment Survey – Total PhosphorusUnlike TN, total phosphorus (TP) concentrations during the summer survey were generally higherthan those observed during winter (Figure 2.4.4), with median concentrations during summer of15µg/L compared to 5µg/L during the winter survey. Figures 2.4.5 and 2.4.6 illustrate graphically,concentrations of TP throughout the catchment showing that TP is generally higher in the region ofLaunceston and the upper catchment of the St Patricks River and North Esk River compared to sitesin the middle of the catchment. The majority of phosphorus in surface waters tends to be carried byparticulate material and is therefore generally mirrored by turbidity, however during both surveysturbidity was generally low (< 5 NTU) and therefore no distinct relationships between turbidity andphosphorus were found. An exception to this was Kings Meadows Rivulet, where high TP duringthe winter (54µg/L) corresponded with higher turbidity (56.2 NTU). The relationship betweenturbidity and TP concentrations is discussed further in section 2.5, where correlations betweennutrients such as TP and turbidity can be used to derive nutrient fluxes.

Seventeen sites from the summer survey recorded TP concentrations above the 13µg/L trigger valuefor upland rivers in Tasmania (ANZECC, 2000). Of particular interest are results from sites locatedbelow the Norwood sewerage treatment plant (NE1, NE2) and Old Mill Creek (NE24). Both NE1and NE2 (Table 2.4.2) recorded high levels of TP with a significant portion of phosphorus at thesesites present as dissolved reactive phosphorous (DRP). These high levels of DRP suggest a probablepoint source contamination from the sewerage treatment plant upstream. This is reinforced by thehigh concentrations of ammonia that were recorded at both these sites (Figure 2.4.3). Table 2.4.2gives concentrations of TP and DRP at five lower catchment sites, and clearly shows the change thatoccurs in nutrient status of the North Esk River below the Norwood treatment plant discharge point.These data also suggest that Kings Meadows Rivulet also contributes to TP concentrations at NE1.

Phosphorus is the nutrient which limits algal growth and therefore controls primary production(UNESCO, 1992). It is widely accepted that that excessive TP concentrations can be linked to theeutrophication of water bodies and algal blooms (Boulton and Brock, 1999; UNESCO, 1992).During summer, higher water temperatures combined with lower flow and elevated nutrientconcentrations at NE2 could result in excessive algal growth in this reach of the river. This couldhave implications for downstream water quality and environmental condition.

Old Mill Creek (NE24) also recorded significantly higher summer TP concentrations compared tothose recorded during the winter survey (Figure 2.4.4.). As stated in section 2.1, this site was subjectto intensive in stream modifications. However during the summer survey NE24 was vegetated witha dense stand of Cumbungi (Typha spp) and therefore it is more probable that the concentrations ofTP experienced at this site is not a function of active stream bank erosion. Rather the density ofCumbungi act to trap sediments to which nutrients such as TP are attached. This is supported by thelow concentrations of DRP sampled at this site (Table 2.4.2).

Figure 2.4.4 also illustrates an increase in TP concentrations within the area encompassing forestryplantations of the upper catchment (eg. NE18). As previously discussed in section 2.4.3 theseconcentrations are likely to represent soil disturbance from cultivation in these areas rather thanfertiliser application.


48

Table 2.4.2 Total phosphorus (TP) and dissolved reactive phosphorus (DRP) at select sites on theNorth Esk River recorded during summer 2000 and winter 1999.

Summer WinterSite Name Site

No TP(µg/L)

DRP(µg/L)

DRP(%)

TP(µg/L)

DRP(µg/L)

DRP(%)

North Esk downstream confluencewith Kings Meadows Rivulet

NE 1 216 174 80.6 24 17 70.8

North Esk downstream Norwood STP NE 2 128 89 69.5 71 66 93.0Kings Meadows Rivulet at Punchbowl NE 3 25 4 16 54 9 16North Esk upstream Clarks Ford Bridge& riffle

NE 4 23 11 47 5 2 40

Distillery Creek upstream confluenceof North Esk

NE 5 10 2 20 2 <2 N/A

Old Mill Creek at Blessington Road NE 24 90 5 5 15 2 13

Site No

NE

1N

E 2

NE

3N

E 4

NE

5N

E 6

NE

7N

E 8

NE

9N

E 10

NE

11N

E 12

NE

13N

E 14

NE

15N

E 16

NE

17N

E 18

NE

19a

NE

19b

NE

20N

E 21

NE

22N

E 23

NE

24N

E 25

NE

26N

E 27

NE

28N

E 29

NE

30N

E 31

NE

32

Tota

l Pho

spho

rus

(ug/

L)

0

50

100

150

200

250

Winter TP Summer TP

ANZECC Guideline 13 ug/L

Figure 2.4.4: Total phosphorus concentrations for the North Esk catchment during winter (June1999) and summer (January 2000) snapshot surveys.


49

Upper Blessington

Rive

r

Rive

r

St

Esk

North

Patri

cks

Pate

rson

iaR

vt

!

Launceston

10

kilometers50

Launceston

Hobart

STUDY AREA

Devonport

Bass Strait

Tributary

Sampling SiteRoads

Legend

Main River

Town

LegendTotal Phosphorus ug/L

26

132.6

Figure 2.4.5: North Esk River total phosphorus summer snapshot concentrations (µg/L) January 2000.


50

Upper Blessington

Rive

r

Rive

r

St

Esk

North

Patri

cks

Pate

rson

iaR

vt

!

Launceston

10

kilometers50

Launceston

Hobart

STUDY AREA

Devonport

Bass Strait

Tributary

Sampling SiteRoads

Legend

Main River

Town

LegendTotal Phosphorous

26

132.6

Figure 2.4.6: North Esk River total phosphorus winter snapshot concentrations (µg/L) July 1999.


51

2.4.2 Catchment Survey – Heavy MetalsSamples taken during snapshot surveys were analysed for some of the main metals commonly foundin waters that may pose some risk to aquatic organisms or human health. Due to financialconstraints, only total metal concentrations were determined. Where high concentrations aredetected it is suggested that future studies at these sites include analysis of the dissolved fraction.The detection limits for those metals analysed are listed below. Detection limits for arsenic changedfrom <1µg/L in August 1999 to <5µg/L in February 2000. This was due to a re-valuation of thelaboratory’s methods of detection as part of their NATA accreditation methods and procedures.

Metal Limit of DetectionAluminium 50µg/LArsenic 5µg/LCadmium 1µg/LCopper 1µg/LLead 1µg/LZinc 1µg/L

Similar to many other parameters commonly tested for in surface waters, metals can be present invarious forms. Trace amounts of some metals are naturally present in surface waters as aconsequence of the weathering of rocks and soil. Metals can be present attached to suspendedmatter, colloids, or complex organic compounds (ie. humic and fluvic acids). The relative toxicity ofmetals is dependant upon the degree of oxidation of the metal ion together with the form it isassociated with (UNESCO, 1992). The toxicity of metals can also vary depending upon theenvironment in which they are found. Acid conditions tend to increase the toxicity of the majority ofmetals whilst for others high concentrations of hardness reduce toxicity (ANZECC, 1992).

Within the new National Water Quality Guidelines for Fresh and Marine Waters (ANZECC, 2000)trigger values for toxicants (ie. metals, pesticides) are derived using a statistical distribution methodcalculated at 4 different protection levels. Each level signifies the percentage of aquaticmacroinvertebrate species expected to be protected. In the majority of cases the 95% protectionlevel should be used for most ecosystems which can be classified as slightly to moderately disturbedand is suggested here as the default level of protection (Table 2.4.1). The general framework forapplying levels of protection for toxicants as suggested by ANZECC 2000 is tabulated inAppendix 1.

Table 2.4.1: Trigger values for observed metals at alternate levels of protection. Values in the greyshaded areas are the trigger values applying to typical slightly to moderately disturbed ecosystems(ANZECC 2000). NOTE: ID = Insufficient data to derive a reliable trigger level.

Metals Trigger Values for freshwater (µg/L-1)

Level of Protection (% species)99% 95% 90% 80%

Aluminium pH > 6.5 27 55 80 150Aluminium pH < 6.5 ID ID ID IDArsenic (As III) 1 24 94 360Arsenic (As V) 0.8 13 42 140Cadmium H 0.06 0.2 0.4 0.8Copper H 1.0 1.4 1.8 2.5Lead H 1.0 3.4 5.6 9.4Zinc H 2.4 8.0 15 31

In Table 2.4.1 ‘H’ represents those metals for which values have been calculated using a hardness of30 mg/L CaCO3 . These should be adjusted based on specific site hardness. However in soft watersbelow a hardness of 25mg/L CaCO3 extra care needs to be taken when considering this option. Due


52

to the low levels of hardness throughout the North Esk catchment (median values of 16 mg/L) it issuggested here that trigger values provided Table 2.4.1 as per ANZECC 2000 are used.

Table 2.4.2 illustrates basic statistics for heavy metals sampled during both surveys. Only thosemetals which recorded high concentrations will be discussed in detail in the following sections(aluminium and zinc). No significant levels of cadmium or arsenic were detected during either thesummer or winter surveys (Table 2.4.2). Lead was only recorded above the detection limit (2µg/L)at six sites during winter and two during summer. Copper was recorded at or below detection limits(1µg/L) at all sites with the exception of Kings Meadows Rivulet at Punchbowl, where the wintercopper concentration (10µg/L) was found to be above the recommended trigger level. This level islikely to be an indication of the quality of runoff from the surrounding urban environment. As thisdata represents total copper concentration further analysis for the dissolved fraction is suggested.

Table 2.4.2: Summary of the data for total metal concentrations collected during the twocatchment snapshot surveys across the North Esk catchment in 1999 and 2000.

Aluminium(µg/L)

Cadmium(µg/L)

Copper(µg/L)

Lead(µg/L)

Zinc(µg/L)

Arsenic(µg/L)

Maximum 597 <1 10 2 72 <5Minimum 50 <1 <1 <1 <1 <1Median 86 <1 1 1 2 3n = 33 sites across the catchment

2.4.2.1. AluminiumOut of all the metals tested, aluminium recorded the most significant results with concentrationsfrom both summer and winter samples throughout the catchment varying both spatially and betweensurveys (Figure 2.4.8 and Figure 2.4.9). Caution must be used when comparing concentrationsrecorded against the ANZECC 2000 trigger values, as these measurements are of ‘Total’ aluminiumas opposed to the more toxic form of ‘dissolved’ aluminium. A proportion of this aluminium is likelyto be absorbed to clays and other suspended particles. The tendency for aluminium to absorb tosuspended particles has been illustrated in other Tasmanian catchments such as the RingaroomaRiver (Bobbi, 1999a) and the Duck River (Bobbi, in press), where higher aluminium concentrationscoincide with higher turbidity levels. In the North Esk catchment the relationship between turbidityand aluminium concentrations from both summer and winter surveys are far less defined, with resultsfrom some sites showing high concentrations of aluminium at low levels of turbidity (Figure 2.4.7).This suggests that at some sites aluminium concentrations are derived from localised sources andmay be independent of turbidity and could be present in its more toxic ‘dissolved’ form.

High concentrations of aluminium in the surface waters of the North Esk catchment may reflectinfluence of geochemical weathering of the surrounding geology which consists of granite intrusionsin the uplands and patches of alluvial Holocene sediments in the river valley. While the data is fortotal aluminium only, it is important to consider that aluminium toxicity is likely to increase at lowpH (< 5.5) and high pH (>9) (ANZECC, 2000). Monthly pH levels at some sites fell 5.5 ( Figure2.1.3) which, in conjunction with low turbidity, suggests that at some sites aluminium has thepotential to be a threat to aquatic fauna.


53

Turbidity (NTU)

0 2 4 6 8 10

Alum

iniu

m (u

g/L)

40

60

80

100

120

140

160

180

June 1999January 2000

Figure 2.4.7: Turbidity vs aluminium concentrations in the North Esk catchment duringsnapshot surveys of June 1999 and January 2000. NOTE: outliers from three sites have beenremoved these are; Kings Meadows Rivulet at Punchbowl (summer sample, tubidity 56.2 NTU,aluminium 317 µg/L), Old Mill Creek at Blessington Road (summer sample, tubidity 16.8 NTU,aluminium 255µg/L and winter sample, turbidity 64 NTU, aluminium 597µg/L).

Total aluminium concentrations from the summer survey (Figure 2.4.6) ranged from 50µg/L to597µg/L, with a median level of 73µg/L and winter survey (Figure 2.4.7) ranged from 50µg/L to317µg/L with a median level of 96µg/L. This is with the exception of Coquet Creek at the TasmanHighway (NE9) and Patersonia Rivulet at Targa Hill (NE11) both of which recorded aluminiumconcentrations below 55µg/L for the summer and winter surveys.

The highest aluminium concentrations were recorded at King Meadows Rivulet at Punchbowl andOld Mill Creek at Blessington Road. The concentration of aluminium at Kings Meadows Rivulet atPunchbowl was significantly higher during winter (aluminium = 317µg/L and turbidity = 56.2 NTU)compared to summer (aluminium = 50µg/L and turbidity = 8.96 NTU), suggesting that aluminium atthis site may be bound to sediment particles, reducing potential toxicity.

Old Mill Creek at Blessington Road recorded high winter and summer concentrations of aluminiumand turbidity. Summer aluminium and turbidity levels were 597µg/L and 64 NTU with winter levelsof aluminium and turbidity recording 255µg/L and 16.8 NTU respectively. High concentrations ofaluminium at Old Mill Creek at Blessington Road is possibly a reflection of the weathering anddecomposition of the surrounding parent material which consists of Holocene sediments high inaluminium. The disturbance of the channel that occurred at this site in early 1999 may havecontributed to the high concentrations of aluminium sampled during both surveys.


54

Upper Blessington

Rive

r

Rive

r

St

Esk

North

Patri

cks

Pate

rson

iaR

vt

!

Launceston

10

kilometers50

Launceston

Hobart

STUDY AREA

Devonport

Bass Strait

Tributary

Sampling SiteRoads

Legend

Main River

Town

LegendAluminium ug/L

150

7055

Figure 2.4.8: North Esk River aluminium summer snapshot concentrations (µg/L) January 2000.


55

Upper Blessington

Rive

r

Rive

r

St

Esk

North

Patri

cks

Pate

rson

iaR

vt

!

Launceston

105

kilometers0

Launceston

Hobart

STUDY AREA

Devonport

Bass Strait

Tributary

Sampling SiteRoads

Legend

Main River

Town

LegendAluminium ug/L

150

7055

Figure2.4.9: North Esk River aluminium winter snapshot concentrations (µg/L) July 1999.


6

2.4.2.2 ZincLow concentrations of total zinc were detected at the majority of sites with most readings in therange 1 to 5 µg/L (Figure 2.4.10). With the exception of Kings Meadows Rivulet at Punchbowl(NE3), there were no sites that showed consistently elevated zinc concentrations. Higherconcentrations were detected during summer at North Esk at Musselboro Road (NE26), SevenMile Creek at Tasman Highway (NE15) and Ford River at Upper Blessington (NE21). It is notclear as to the origin of zinc concentrations at these sites, but it may be related either togeological influences or to the possible application of fertilisers that may contain zinc. Zinc canbe present in surface waters due to natural processes (weathering of parent material, soil erosion)or anthropogenic (waste incineration, domestic disposal of household products, mining)(ANZECC, 2000). The high concentration of zinc found at Kings Meadows Rivulet (NE3) islikely to originate from the disposal of house-hold products. Zinc is a metal commonly used inmay domestic products and ranks fourth highest among other metals (ie iron, aluminium andcopper) in the worlds annual consumption (Nagpal, 1999). Some of the major uses of zinc fordomestic products include rust-resistant coating for galvanised iron, powders, ointments,antiseptics and astringents, paints, varnishes, fertilisers and insecticides (Napgal, 1999).Therefore it can be assumed that the high concentration of zinc at NE3 originates from urbanrunoff, and at these concentrations are likely to effect instream biological process. However thedata presented here represent total values only and therefore further sampling must beundertaken to better quantify the level of environmental threat. Management of zinc in this sub-catchment may involve increasing community awareness in regarding the disposal of varioushousehold items that contain zinc.

S ite N o

NE

1N

E 2

NE

3N

E 4

NE

5N

E 6

NE

7N

E 8

NE

9N

E 10

NE

11N

E 12

NE

13N

E 14

NE

15N

E 16

NE

17N

E 18

NE

19a

NE

19b

NE

20N

E 21

NE

22N

E 23

NE

24N

E 25

NE

26N

E 27

NE

28N

E 29

NE

30N

E 31

NE

32

Tota

l Zin

c (u

g/L)

0

10

20

30

40

50

60

70

80

Sum m er W inter

Figure 2.4 10: Total zinc concentrations recorded during July 1999 and January 2000.


2.4.5 Catchment Survey – BacteriaSampling for coliforms was conducted at all sites during both summer and winter surveys. Testingon both occasions was carried out for total coliforms, faecal (‘thermotolerant’) coliforms (asEscherichia coli) and faecal streptococci. As faecal coliforms are the indicator most often used toassess bacterial contamination in waterways, only E.coli results will be discussed in this section.The raw data from these surveys is given in Appendix 1. Because this sampling is only a snapshot, itis not appropriate to compare results against the ANZECC guidelines. The guidelines stipulate thatevaluation of microbiological quality should be based on median levels from data collected fromroutine monitoring. The results presented here aim only to highlight areas within the North Eskcatchment where water quality may be affected by faecal pollution. Where higher levels of faecalbacteria are reported, further investigation may be required to determine the level of pollution.

Results from the study show that faecal coliform levels across the catchment were generally higherduring the summer survey than those recorded during the winter survey (Table 2.4.3). Seventeensites recorded summer concentrations above the proposed microbiological guidelines for primarycontact of 150 per 100ml (ANZECC, 2000) in comparison with 6 sites during the winter survey.

Summer snapshot data on the North Esk River indicates that sites in the middle and lower reaches ofthe river have the highest input of faecal contamination. Middle catchment sites, mainly betweenWatery Plains and Upper Blessington, are composed mainly of agricultural lands with sections of theriver having unrestricted access for stock, and this is likely to explain the higher faecalconcentrations. Sites in the upper North Esk River, which are located within forestry areas, recordedlow concentrations of faecal coliforms and were perhaps more representative of backgroundenvironmental levels. North Esk River at Camden Road (NE20) shows a relatively high faecalcoliform level, suggesting that the Ford River catchment is a possible source contamination (Figure2.4.11). Faecal coliform concentrations remain relatively high along the main stream length, withMusselboro Creek (NE25) also appearing to have a significant input into the main stream.Concentrations remain relatively high through until the confluence with the St Patricks River, whenfaecal concentrations appear to decline. In the lower catchment, high levels of faecal coliforms werefound at the bottom site of Distillery Creek upstream of the North Esk River (NE5), at KingsMeadows Rivulet at Punchbowl (NE3) and in the North Esk River downstream of the confluence ofKings Meadows Rivulet (NE3).

Data from the winter survey generally showed faecal coliform concentrations lower than thoserecorded during the summer survey (Figure 2.4.12). This is with the exception of Kings MeadowsRivulet at Punchbowl (2400 per 100ml), River O’Plain Creek at Blessington Road (NE23) and OldMill Creek at Blessington Road (NE24). The later two sites registering a coliform count of 160 per100ml each. These data show that high coliform levels recorded in the lower North Esk River (ieNE1) mainly represent inputs from Kings Meadows Rivulet (NE3) and to a lesser extent DistilleryCreek (NE5).

Environmental factors can greatly influence the survival of faecal coliforms outside of the gut, andlocations that have high rates of deposition and elevated turbidity and nutrient levels more adequateenvironmental conditions to sustain faecal coliforms for longer. Kings Meadows Rivulet atPunchbowl is a site that has consistently shown high concentrations of both nutrients and turbidity,therefore the level of faecal coliform contamination at this site may also reflect coliformconcentrations in the sediments as well as runoff from an urbanised area. The high winter surveyconcentrations are likely to be representative of increased runoff from surrounding urbanised areas.


8

Table 2.4.3: Eschericha.coli concentrations (colony count per 100ml) in the North Eskcatchment during summer and winter snapshot surveys June 1999, January 2000).

E. coli (Count per 100ml)SITE NAME Site No Summer WinterNorth Esk River downstream of the confluence of KingsMeadows Rivulet

NE 1 490 60

North Esk River downstream of Norwood sewerage treatmentplant

NE 2 130 20

Kings Meadows Rivulet at Punchbowl NE 3 600 2400North Esk River upstream of Clarks Ford Bridge and riffle NE 4 92 30Distillery Creek upstream of the confluence of the North EskRiver

NE 5 370 70

Distillery Creek upstream of the filtration plant NE 6 140 50St Patricks River at Nunamara NE 7 420 210Patersonia Rivulet at Patersonia Road NE 8 130 210Coquet Creek at Tasman Highway (Trout Ck) NE 9 110 30St Patricks River at Pecks Hill Road NE 10 170 60Patersonia Rivulet at Targa Hill NE 11 70 10Barrow Creek at Tasman Highway NE 12 270 230Bennies Creek at Tasman Highway NE 13 390 10St Patricks River at Targa Hill Road NE 14 180 40Seven Mile Creek at Tasman Highway NE 15 730 10St Patricks River at Corkerys Road NE 16 40 70St Patricks River at East Diddleum Road NE 17 30 30Camden Rivulet at Diddleum Road NE 18 130 150North Esk River off Camden Road NE 19a 10 80North Esk River at Phillps Road NE 19b 130 130North Esk River at Camden Road NE 20 430 70Ford River at Upper Blessington NE 21 590 100North Esk River at Burns Creek Road NE 22 490 80River O'Plain Creek at Blessington Road NE 23 90 160Old Mill Creek at Blessington Road NE 24 80 160Musselboro Creek upstream of the North Esk River NE 25 830 10North Esk River at Musselboro Road NE 26 710 60North Esk River at Ballroom NE 27 520 30North Esk River upstream of the confluence of the St PatricksRiver

NE 28 900 90

St Patricks River upstream of the confluence of the North EskRiver

NE 29 150 30

North Esk river at White Hills NE 30 140 80Rose Rivulet above Patersons Island NE 31 40 140North Esk River at Corra Linn NE 32 210 30


59

Upper Blessington

Rive

r

Rive

r

St

Esk

North

Patri

cks

Pate

rson

iaR

vt

!

Launceston

105

kilometers0

LegendE.coli (per 100 mL)

1,500

750150

Launceston

Hobart

STUDY AREA

Devonport

Bass Strait

Tributary

Sampling SiteRoads

Legend

Main River

Town

Figure 2.4.11: North Esk River E.coli summer snapshot concentrations (µg/L) January 2000.


60

Upper Blessington

Rive

r

Rive

r

St

Esk

North

Patri

cks

Pate

rson

iaR

vt

!

Launceston

105

kilometers0

Launceston

Hobart

STUDY AREA

Devonport

Bass Strait

Tributary

Sampling SiteRoads

Legend

Main River

Town

LegendE.coli (per 100ml)

1,500

750150

Figure 2.4.12: North Esk River E.coli winter snapshot concentrations (µg/L) July 1999

water quality of rivers in the north esk catchment · state of rivers water quality of the north...

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