Swimming sites show improved water quality
November 19, 2008
Swimming sites show improved water quality, new Google maps connection
Swimming water quality in Canterbury’s rivers, lakes and sea is showing signs of improvement with nine sites getting a better swimming water quality grade from Environment Canterbury (ECan) scientists in 2008 when compared to last year.
This summer, 83 swimming spots monitored by ECan are considered good for swimming. At 23 sites, swimming is not recommended. Only one site has seen a deterioration of its grade - from good to fair – Lake Middleton (near Lake Ohau, near Twizel).
The grades are based on up to five years of monitoring data and a risk analysis of possible nearby pollution sources. The overall grades are set in November each year and do not change during summer, although the weekly bacterial readings may vary from week to week depending on local conditions like heavy rainfall. Information about the grades can be found at www.ecan.govt.nz/swimming.
“It’s good to see that water quality has improved at a number of swimming spots,” says Cr Mark Oldfield, ECan chair water portfolio. “We encourage people to check the ECan website to see how their local swimming spot is graded. But even good swimming sites should be avoided immediately after heavy rainfall, which can wash contaminants off roadways and gutters into the river or sea.”
Among the improved sites are some well-known swimming spots such as Ashley River/Rakahuri at the gorge, Waimairi Beach, Christchurch, Okains Bay estuary, Banks Peninsula and South Canterbury’s Lake Opuha at the recreation reserve. All went from fair to good. Sandy Bay, at Governors Bay, Banks Peninsula, went from poor to fair which means it is now safe to swim there most of the time.
Weekly water quality monitoring at popular swimming spots started on November 17. ECan is monitoring 54 freshwater (rivers and lakes) and 46 coastal swimming sites this summer.
Change to the web information supplied by
This year the grades are displayed on the ECan website in a new format: a Google maps ‘mashup’. This combines one or more sources of information to create a single application. In this case, ECan has combined its water quality data with Google maps.
“By ‘mashing’ our data with Google maps we have created a service which is easier for us to maintain,” says Dana Burnett, ECan web officer. “With Google maps being used by more and more websites, many users may already be familiar with this map, making it easier to use this ECan service. Although Google maps application is being used by many other organisations, we believe that this is the first time that a Google maps mashup is being used for water quality information.”
Some swimming water quality grades for 2008/09:
Very good: Considered satisfactory for swimming at all times.
Good: Satisfactory for swimming most of the time.
Fair: Generally satisfactory for swimming, though there are many potential sources of faecal material.
Poor: Generally not suitable for swimming, as indicated by historical results.
Very poor: Avoid swimming, as there are direct discharges of faecal material.
South Bay: good
Gooches Beach: good
Armers Beach: fair
Kahutara River/ Peketa: fair (not after rain)
Leithfield Beach: very good
Waikuku Beach: very good
Pines Beach: good
Spencerville Beach: very good
New Brighton: good
Taylors Mistake: very good
Governors Bay Sandy Bay: fair
Corsair Bay: fair
Diamond Harbour Bay: good
Akaroa Beach: good
Wainui Beach: good
Okains Bay and Estuary: good (estuary: not after rain)
Lake Hood: good
Ashburton River (several sites upstream and downstream of Ashburton town): very poor
Caroline Bay: good
Opihi River (several sites): good (not after rain)
Temuka River (SH1 bridge): fair
Pareora River (Brassells bridge): good (not after rain)
Pareora River (Evans Crossing): fair (not after rain)