Liffey Stream Water Testing, Lincoln

Click to see the results from our annual water testing:

2016 Results

2015 Results

To see results from previous years click here.       

 

Liffey Stream Test Results 2016

Liffey Stream Test Results:  Place of test: 2468453E, 5729808N Near North Belt Bridge

Test Date: 13th September 2016      

Weather conditions: sunny with a few clouds, little wind at the start but getting colder and windier. Wind from the SW.

 

Test

Excellent/ good

Satisfactory

Unsatisfactory

 

Results stream

Quality

pH

7.0

6.5 - 8.9

Less than 6.5 or more than 9

7.3

Good

Conductivity (µS/cm)

Less than 100

100 - 500

More than 500

259

Satisfactory

Dissolved Oxygen (mg/L)

     

6.25

Unsatisfactory

Oxygen Saturation (%)

More than 90

80 - 90

Less than 80

68.6

Unsatisfactory

Nitrate (NO3-Nmg/L)

Less than 0.15

0.15 - 0.5

More than 0.5

3.4

Unsatisfactory
Degraded

Phosphate (PO4 mg/L)*

Less than 0.01

0.01 - 0.03

More than 0.03

0.42

Unsatisfactory

Degraded

Turbidity (NTU)

Less than 2

2.5

More than 5

1.85

Good

WaterTemperature (°C)

     

12.9

 

Coliforms

See details in the appendix

   

600

Satisfactory

E.Coli CFUs/100mL

(Indicator bacteria for faecal pollution)

Less than 260

(Acceptable)

 261-550

(Alert)

Over 550

(Action, inform public, put up signs)

4

Good

Salmonella CFUs/100mL

 

 

Safe level for swimming is zero

33

 Unsatisfactory

Conclusions:

Almost NO Invertebrates found: only segmented worms (very tolerant of pollution) and a very few amphipods which are also tolerant of pollution, which gives a pollution rating of poor.  This is much worse than last year, and shocking!  This may be because of the unusually low oxygen levels, which might be because of the large amount of leaf litter in the stream from the deciduous exotic trees. This is being decomposed by bacteria, removing oxygen from the water.

The nitrate concentration was lower than last year, 3.4mg/L compared with 4.4 but still higher than 2.1 mg/L from 2013. Phosphate was higher, 0.42, compared with 0.27 in 2015 and 0.22   in 2014 but still slightly lower than 0.39 mg/L from 2013. All phosphate readings are still very high!

The water was also tested for bacteria for E.coli, which is an indicator for faecal pollution. There were only 4 CFU per 100 mL which was much lower than last year when it was 154 and 2013 when it was 150. However the level of salmonella, which are harmful to people, was high. These may come from ducks, although the level of E.coli was very low, and we saw no sign of ducks. These mostly live farther downstream. So there may be another source. Safe of Salmonella level for swimming is zero (see information below)

There is no simple way to tell if E. coli found in a river is from animal or human faeces, but where animal faeces are present other bacteria including Campylobacter and Cryptosporidium are likely (Davies-Colley & Wilcock, 2004). Salmonella is found in both warm- and cold-blooded animals, and is usually associated with bird life, and can cause food poisoning in humans. 

Notes and Appendices

Notes: * Ecan gives their results to elemental ‘P’, to get this from the PO4 divide the results by 3.07 to make a comparison.

**The E.coli counts were graded using the Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas, although only one sample was tested. Published in June 2002 by the Ministry for the Environment Manatu Mo Te Taiao PO Box 10-362, Wellington, New Zealand. Updated in June 2003. ISBN: 0-478-24091-0 ME number: 474.This document is available under publications on the Ministry for the Environment’s website: www.mfe.govt.nz

E. coli is used as an indicator of contamination of drinking-water by faecal material.  The Maximum allowed for E. coli is less than 1 E. coli in 100 mL of sample. Drinking-water Standards for New Zealand 2005. Colony Forming Units (CFUs) correspond to the number of bacteria in the sample. Colonies, made of millions of bacteria, and so visible to the naked eye, are counted. Each colony has grown from one bacterium in the sample when it incubated on a plate containing culture medium.

                

 

 

 

Liffey Stream Test Results 2015

Liffey Stream Test Results:      Place of test: 2468453E, 5729808N Near North Belt Bridge    

 

Test Date: 14th September 2015          Weather conditions: sunny with a few clouds, little wind.

 

Test

Excellent/ good

Satisfactory

Unsatisfactory

 

Results stream

Quality

pH

7.0

6.5 - 8.9

Less than 6.5 or more than 9

7.1

good

Conductivity (µS/cm)

Less than 100

100 - 500

More than 500

303

Satisfactory

Dissolved Oxygen (mg/L)

 

 

 

7.6

 

Oxygen Saturation (%)

More than 90

80 - 90

Less than 80

73%

 Satisfactory

Nitrate (NO3-Nmg/L)

Less than 0.15

0.15 - 0.5

More than 0.5

4.4

Unsatisfactory
Degraded

Phosphate (PO4 mg/L)*

Less than 0.01

0.01 - 0.03

More than 0.03

0.27

Unsatisfactory

Degraded

Turbidity (NTU)

Less than 2

2.5

More than 5

1.92

 Good

WaterTemperature (°C)

 

 

 

12.8

 

E.Coli CFUs/100mL

(Indicator bacteria for faecal pollution)

 Less than 260

(Acceptable)

 261-550

(Alert)

 Over 550

(Action, inform public, put up signs)

154

Acceptable  for recreation  (not for drinking!)

Salmonella CFUs/100mL

 

 

 

22.5

 

Conclusions:

Invertebrates found: cased caddis fly larvae, amphipods, caddis fly larvae (free), water snails,  segmented worms.  By far the greatest number found were amphipods and segmented worms, as last year, which gives a pollution rating of poor. One specimen of Phreatogammarus fragilis, was found. We have only found this once before when testing the water from the Liffey stream.  It is a small colourless amphipod which inhabits aquifers and springs throughout central Canterbury. It's often found in spring-fed streams, notably the lower Selwyn River

The nitrate concentration was lower than last year, 4.4mg/L compared with  5.5 but still higher than 2.1  mg/L from 2013. Phosphate was slightly  higher, 0.27 compared with 0.22  but still lower than 0.39 mg/L  from 2013. All phosphate readings are still very high!

The water was also tested for bacteria for E.coli , which is an indicator for  for faecal pollution . There were  154 CFU per 100 mL which was similar to last year when it was 150.

There is no simple way to tell if E. coli found in a river is from animal or human faeces, but where animal faeces are present other bacteria including Campylobacter and Cryptosporidium are likely (Davies-Colley & Wilcock, 2004). Salmonella is found in both warm- and cold-blooded animals, and is usually associated with bird life, which causes food poisoning in humans. The ducks which are found swimming in the Liffey stream were probably the source of the salmonella. 

 

Additional Comments: Conclusions:

Notes: * Ecan gives their results to elemental ‘P’, to get this from the PO4 divide the results by 3.07 to make a comparison.

**The E.coli counts were graded using the Microbiological Water Quality Guidelines for Marine and Freshwater Recreational Areas, although only one sample was tested. Published in June 2002 by the Ministry for the Environment Manatu Mo Te Taiao PO Box 10-362, Wellington, New Zealand. Updated in June 2003. ISBN: 0-478-24091-0 ME number: 474.This document is available under publications on the Ministry for the Environment’s website: www.mfe.govt.nz

E. coli is used as an indicator of contamination of drinking-water by faecal material.  The Maximum allowed for E. coli is less than 1 E. coli in 100 mL of sample. Drinking-water Standards for New Zealand 2005. Colony Forming Units (CFUs) correspond to the number of bacteria in the sample. Colonies, made of millions of bacteria, and so visible to the naked eye, are counted. Each colony has grown from one bacterium in the sample when it incubated on a plate containing culture medium.