"It is early morning and I'm sitting on the bank of a small creek that drains into Kaikorai Stream in western Dunedin.
Bending forward, I lift a dark stone from the creek bed and turn it over.
The stone is covered with movement, but it is hard to see what is causing the commotion.
So I plunge the cobble into a white dish and the movers are dislodged: mayfly nymphs - a good sign.
The nymphs are something to behold.
About a centimetre long, dark brown and with flattened bodies, they are well adapted for their living space.
Most impressive are their thin, delicate, and frantically moving gills.
These extract oxygen gas from the water so the animal can breathe.
I often come back to this creek and look for life.
I wonder how this trickle and its bigger destination must have looked years ago.
You see, mayfly nymphs have another attribute.
Like the canary in the cage, they can tell us a lot about the quality of the place in which they live.
They need a clean, cool place with plenty of food and life-giving oxygen.
Without that, they die or move away in search of a better home.
Sadly the health of their home, one of our urban waterways, continues to fade.
It has become hard to find a mayfly nymph along the main stem of Kaikorai Stream although the type of habitat they prefer is certainly there.
A 2008 Otago Regional Council report confirmed that the health of Dunedin's urban streams, and the Kaikorai Stream in particular, was poor.
Indeed, one of our regional councillors was moved to describe the water quality as "basically crap".
Despite our improved understanding of many environmental issues, pollution events, and report after report that outlines problems with our waterways, we are still slow to act.
What is the solution? It all comes down to what we are prepared to pay and do to show that we care about our living space.
Much good work has been and is being done on urban waterways, but the scale of the problem is vast.
We add to it every day.
Toxic heavy metals come from the brake linings and tyres of my car as I travel on roads to and from work.
Clay and silt are exhumed during earthworks at sites for new developments.
Faecal matter and nitrogenous chemicals seep or are discharged into the streams from septic tanks, sewer lines and animal activity.
Particles of soot and ash are emitted into the air.
None need be produced that close to a stream to have an effect.
In the next storm, all the muck from the land and the air will enter the waterway, via natural waterways and the stormwater drainage system.
The biggest barrier to maintaining and enhancing our waterways is that they occupy a marginal place in the minds of most of us.
Something that is marginal to our core thinking receives less attention.
It is less important.
Yet the payback for protecting and enhancing waterways is measurable and valuable.
These streams indicate just how good we are at living in balance with the air, land, and water around us.
On a recent weekend a cruise ship full of tourists berthed at Port Chalmers.
No doubt these tourists were keen to visit our city and appreciated its beauty.
Yet, I wonder how they would feel about a city in which it is still possible for raw sewage to enter one of its local waterways.
In 1908, Short described Kaikorai Stream thus: "it is nothing but an open sewer carrying sewage, factory refuse and filth of all descriptions".
In 2010, it seems not a lot has changed.
Criticising DCC or ORC staff is not the answer.
This easy line of culpability fails to understand the complex practical problems involved with dealing with waste and stormwater infrastructure and fixing water-quality events.
What is required here is an integrated catchment management plan.
Such a plan, effectively implemented, could be as marketable for our city's image as any other type of development.
How good, how special, how instructive of our values, it would be to boast that even in an urban environment our streams are cared for - as we work, recreate and develop around them.
If this plan had already been in place, the value of urban waterways would be recognised and priority given to funding alarm systems on sewage system overflow pipes and/or monitoring sites in the stream.
A turbidity (how cloudy the water is) sensor connected in real time to DCC and ORC offices would have identified the recent sewage pollution event and remedial action could have been taken much earlier than it was.
Kaikorai Stream is constantly under pressure and this will only increase as urban development continues.
Doing something about Kaikorai Stream strikes at the very heart of what our city wants to be.
It could be a leader among cities - a sustainable city, the best there is."
• Simon McMillan is a Dunedin teacher.
