River Health in the New South Wales Lower North Coast, Hunter and Central Coast Catchments

A report of AusRivAS assessments 1994 - 1999
Grant Hose and Eren Turak
Environment Protection Agency, 2004
ISBN 0 642 55099 9 ISSN 1447-1280

Hunt578 - Merriwa River at Cullingral Road

Site Condition Summary
Sampling Data and Assessments
Site report cards

Site Condition Summary

The Merriwa River flows through grazing land before reaching this site downstream of Merriwa. Some of the native riparian vegetation remained but the riparian community was dominated by exotic species including willow.

Cattle access appeared to have degraded the instream habitat. Extensive algal growth was noted on both sampling occasions. In Spring, phosphorus and nitrogen (TKN) concentrations were high and dissolved oxygen was low.

Despite the apparently degraded habitat, the macroinvertebrate communities were in good condition. Samples from the edge habitat gave O/E-Taxa values of 1.13 and 0.87 for Autumn and Spring samples respectively. These communities were similar to those expected under reference condition. Macroinvertebrate communities in the riffle habitat indicated a greater degree of impairment than those in the edge habitat. O/E-Taxa values for riffles were 0.82 and 0.70 for Autumn and Spring respectively. The combined season model indicated even greater impairment, giving an O/E-Taxa value of 0.60. Notably absent from the riffle samples were Gripopterygidae (stone flies) and Corydalidae (alder flies) which are common predators in fast flowing upland streams.

Location Map

Location Details
Map Name	Gungal 8933-2-N
Map Zone	56
Map Scale	1:25000
Easting	248200
Northing	6424700
Distance from source (m)	58777
Elevation (m asl)	190
Average Annual Rainfall (mm)	650

Single Season Assessments

Edge
	Autumn '99	Spring '99
	6-May-99	14-Dec-99
O/E Taxa	1.13	0.87
Band	A	A
O/E SIGNAL	0.96	0.95

Riffle
	Autumn '99	Spring '99
	6-May-99	14-Dec-99
O/E Taxa	0.82	0.70
Band	B	B
O/E SIGNAL	0.94	0.92

Combined Season Assessments

Edge
Seasons	AUT99SPR99
Model	Eastern
O/E Taxa	0.98
Band	A
O/E SIGNAL	0.98

Riffle
Seasons	AUT99SPR99
O/E Taxa	0.6
Band	B
O/E SIGNAL	0.87

Taxa Collected

X= Taxa Predicted & Collected, O = Taxa Predicted & NOT Collected, + = Taxa Collected & NOT Predicted

Edge
			Autumn '99	Spring '99
Phylum	Class/Order	Family	6-May-99	14-Dec-99
Arachnida	Hydracarina		+	O
Crustacea	Decapoda	Atyidae	X	X
Crustacea	Decapoda	Palaemonidae	+	+
Crustacea	Ostracoda	Ostracoda	+
Insecta	Coleoptera	Curculionidae	+
Insecta	Coleoptera	Dytiscidae	X	O
Insecta	Coleoptera	Elmidae		O
Insecta	Coleoptera	Hydraenidae		+
Insecta	Coleoptera	Hydrophilidae	X	O
Insecta	Diptera	Chironominae	X	X
Insecta	Diptera	Culicidae	+
Insecta	Diptera	Orthocladiinae	X	X
Insecta	Diptera	Simuliidae	+
Insecta	Diptera	Tanypodinae	O	X
Insecta	Ephemeroptera	Baetidae	X	X
Insecta	Ephemeroptera	Caenidae	X	X
Insecta	Ephemeroptera	Leptophlebiidae	X	X
Insecta	Hemiptera	Corixidae	X	X
Insecta	Hemiptera	Gerridae	X	+
Insecta	Hemiptera	Hydrometridae		+
Insecta	Hemiptera	Notonectidae	X	X
Insecta	Hemiptera	Veliidae	X	O
Insecta	Odonata	Coenagrionidae	+	+
Insecta	Odonata	Gomphidae	O
Insecta	Plecoptera	Gripopterygidae		O
Insecta	Trichoptera	Ecnomidae	+	+
Insecta	Trichoptera	Hydrobiosidae		+
Insecta	Trichoptera	Hydroptilidae	+	+
Insecta	Trichoptera	Leptoceridae	X	X
Mollusca	Gastropoda	Limacidae	+

X= Taxa Predicted & Collected, O = Taxa Predicted & NOT Collected, + = Taxa Collected & NOT Predicted

Riffle
			Autumn '99	Spring '99
Phylum	Class/Order	Family	6-May-99	14-Dec-99
Annelida	Hirudinea			+
Annelida	Oligochaeta		X	X
Arachnida	Hydracarina			O
Crustacea	Decapoda	Atyidae		O
Crustacea	Decapoda	Palaemonidae	O
Crustacea	Ostracoda	Ostracoda	+
Insecta	Coleoptera	Dytiscidae		+
Insecta	Coleoptera	Elmidae	X	X
Insecta	Coleoptera	Gyrinidae		+
Insecta	Coleoptera	Hydrophilidae	+
Insecta	Coleoptera	Psephenidae	+	+
Insecta	Collembola	Collembola	+
Insecta	Diptera	Chironominae	X	X
Insecta	Diptera	Diptera		+
Insecta	Diptera	Dolichopodidae	+
Insecta	Diptera	Muscidae	+
Insecta	Diptera	Orthocladiinae	X	X
Insecta	Diptera	Simuliidae	X	X
Insecta	Diptera	Tabanidae	+
Insecta	Diptera	Tanypodinae	O	O
Insecta	Diptera	Tipulidae		+
Insecta	Ephemeroptera	Baetidae	X	X
Insecta	Ephemeroptera	Caenidae	X	X
Insecta	Ephemeroptera	Leptophlebiidae	X	X
Insecta	Hemiptera	Corixidae		+
Insecta	Megaloptera	Corydalidae	O	O
Insecta	Odonata	Gomphidae	X	X
Insecta	Plecoptera	Gripopterygidae	O	O
Insecta	Trichoptera	Ecnomidae		+
Insecta	Trichoptera	Hydrobiosidae	O	O
Insecta	Trichoptera	Hydropsychidae	X	X
Insecta	Trichoptera	Hydroptilidae		O
Insecta	Trichoptera	Philopotamidae		O
Mollusca	Bivalvia	Corbiculidae	X	O
Mollusca	Gastropoda	Thiaridae	+
Platyhelminthes	Turbellaria	Dugesiidae	O

Water Quality Data

	Autumn '99	Spring '99
Variable	6-May-99	14-Dec-99
Water Temperature (°C)	14.8	26.8
Conductivity (µS/Cm)	982	1034
Dissolved Oxygen (mg/L)	10.5	5.8
Alkalinity (mg CaCO₃ /L)	200	9
pH	8.8	8.48
Turbidity (NTU)	7.2	25.3
Low Total Phosphorus (µg/L)	250	340
Free Reactive Phosphorus (µg/L)	47	220
NOx Nitrogen (µg/L)	3	7
Total Kjeldahl Nitrogen (mg/L)	<0.3	0.45
Ammonia (µg/L)	<3	<3
Nitrate (µg/L)	3	6
Nitrite (µg/L)	<1	<1

Key

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