Water Quality Watch: Freshwater monitoring results deteriorating with rainfall

The water quality in a number of the waterways of Doubtless Bay and Northland has deteriorated over the last 10 days.

Water quality monitoring carried out by Doubtless Bay Community Care for Our Catchment and Northland Regional Council over the last 10 days have both recorded deterioration in water quality in a number of waterways.

Rainfall = Increased overland runoff = Deterioration in water quality

In general terms, the long dry period Northland has been experiencing has resulted in improved freshwater quality. However, the rainfall experienced over the last 10 days has resulted in deteriorating water quality at a number of sites.

Doubtless Bay Community Care for Our Catchment monitoring results:

Water quality sample results taken by Doubtless Bay Community Care for Our Catchment on 29 January have highlighted the decline in water quality in Doubtless Bay compared to the previous month’s monitoring. Results of the monitoring are shown below:

A PDF copy of all the monitoring results are below:

Water Quality Results January 10 Results.pdf

For more information on Doubtless Bay Community Care for Our Catchment please click here.

Northland Regional Council monitoring results:

Each summer, Northland regional Council test the water quality at a number of Northland’s popular coastal and freshwater swimming spots to make sure it’s safe for swimming. The testing starts in December each year and continues for 12 weeks through to March the following year.

Northland Regional Council notes that heavy rainfall received earlier this week has led to high levels of bacteria at some freshwater sites, and recommends avoiding swimming for 24 to 48 hours after heavy rainfall.

Samples taken week beginning 01 February 2010:

Status system

NRC give a three tier status system for swimming water quality (the same system used by Doubtless Bay Community Care for Our Catchment).  This is based by assessing the risk of contamination at a freshwater swimming site using levels of the indicator bacteria Escherichia coli (E. coli).  Find out more about what NRC test for

 Green: safe to swim
 Escherichia coli count less than 260/100ml

 Orange: caution, potentially unsuitable to swim
 Escherichia coli count more than 260/100ml

 Red: unsafe to swim
 Escherichia coli count more than 550/100ml

This week's results

The table below shows the most recent results for all the freshwater sites sampled in Northland.  All locations are in alphabetical order.

LOCATION	Site No.	Status	Result
Coopers Beach Stream	101870	Red:  Unsafe to swim	3255
Kaihu River, at campground	102221	Red:  Unsafe to swim	754
Kapiro Bridge, at Purerua Road	102838	Red:  Unsafe to swim	586
Kerikeri, Stone Store bridge	101530	Green:  Safe to swim	97
Lake Taharoa	105434	Green: Safe to swim	31
Langs Beach Stream	104539	Red:  Unsafe to swim	5492
Ocean Beach Stream	102077	Green: Safe to swim	160
Omamari Beach Stream	102305	Red: Unsafe to swim	728
Otamure Bay Stream	108859	Green:  Safe to swim	106
Otaua Stream	108510	Red:  Unsafe to swim	2143
Raumanga Stream, Whangarei	103246	Orange:  Caution	546
Tirohanga Stream	102252	Green:  Safe to swim	86
Twin Bridges	105973	Red:  Unsafe to swim	8164
Victoria River	104908	Red:  Unsafe to swim	3654
Waipapa Basin	105706	Green:  Safe to swim	85
Waipapa River, Puketi	103248	NOT AVAILABLE
Waipoua River, at DOC campground	108613	Red: Unsafe to swim	1607
Waipu Stream	101207	Green:  Safe to swim	62
Waitangi, at Lily Pond	104830	Orange:  Caution	464
Waro Lake, Hikurangi	107272	Green:  Safe to swim	86
Whangarei Falls	105972	Red:  Unsafe to swim	749

Check before you swim

In general, water can be contaminated and unsafe for swimming if:

• there is a warning sign erected indicating water is unsafe.
• there has been heavy rain recently.
• the water looks dirty (murky).
• there are several potential sources of contamination nearby and upstream such as:
  • houses on septic tanks;
  • stock with access to the water; or
  • a sewage treatment plant discharge.

Click here for more information on Northland Regional Council.