How might we get the Waikawa Stream back to being clean and swimmable?
We know that the Waikawa Stream isn’t as clean as it used to be (The river runs red), and many of us have our suspicions about why that might be, though we lack the data to confirm the sources of the problem.
The article Troubled Waters in the New Zealand Geographic is a long and careful look at contamination in New Zealand rivers and makes many very interesting points. I suggest you set aside half an hour and read it.
The conclusion of the article is particularly interesting and gives us some useful ideas:
Young believes that correct diagnosis coupled with professional support can lead not just to an immediate improvement in river health but long-term benefits in preventive care. In the Sherry River catchment, for example, the shock of landowners and residents at finding their beloved stream was, in fact, a microbial health hazard galvanised the community to form a catchment group.
Cattle crossings were bridged, leading to a 50 per cent improvement in water quality. Five kilometres of waterways were fenced, and 4000 trees, shrubs and grasses planted in riparian margins. Multiple other measures to control run-off and limit soil erosion were implemented, leading to the group receiving environmental awards in 2009 and 2013.
The community’s enthusiasm for their local river had another benefit: they published their story as a case history. Others can now refer to this “medical literature” and learn from the Sherry River experience.
Sometimes now the Waikawa stream is not swimmable. Next we need to know why and then we can start working on the changes needed to get it back to the safe and fun river so many have enjoyed over the years.
In the summer of 2016–2017 the river by the footbridge often had elevated levels of dangerous E. coli.
Waikawa Beach is a popular spot for swimming, kayaking, fishing and puddling about in the water. Each summer the water is tested weekly at various spots around the country, including at and near Waikawa Beach.
Summer season monitoring: Many councils monitor popular recreational sites weekly over the summer months. This lets swimmers know what the most recent bacteria (E. coli) levels were. Remember, even for sites where the monitoring has shown an acceptable to swim test result, some conditions can make them unsuitable to swim in from time to time and we recommend that you avoid swimming after heavy rainfall for 48 hours.
Note: The quality of water for swimming is determined by measuring ‘faecal indicator bacteria’ (enterococci in coastal waters and E. coli in rivers and lakes) which indicate the levels of disease causing organisms in the water.
An E. coli count below around 260 or an enterococci count below around 200 is acceptable. Above that moves to Alert or Unacceptable. Acceptable counts have been marked in bold and green in the table below.
In the table below, columns are for Waikawa at North Manakau Road (E. coli), Waikawa Estuary at Footbridge (E. coli), and Tasman Sea at Waikawa Beach (enterococci). There’s no rainfall or river flow data in the table, but personal observation is that this summer was exceptionally rainy.
Notice how the water up the road at North Manakau Road is very often green, or acceptable, while some 7 to 10 Km downstream here by the footbridge it’s very often not green. In the sea though seems to be mainly OK.
More detailed research on all of this and on ways to clean up our swimming water would be an excellent thing.