Wednesday, 24 June 2015

Healthy waterway report Joshua miller

Christchurch Waterways

Fresh waterways in Christchurch include rivers, streams, wetlands, lakes and more. Man-made waterways include stormwater systems, piped systems, water races, artificial drains and some others. When it rains, if it goes on to concrete it falls into the gutters, then flows into the drains, then the river, then the ocean.


A habitat is a home for animals and insects to live, and it makes shelter and shade and provides food to eat. An ideal shelter for a fish is under sticks lying around for shelter. Most of our rivers and creeks are polluted because people are littering making our waterways unhealthy. We need to stop - this is where they live and they may get stuck and die.

Everything in a habitat is connected

Crayfish relies on the common bully because the freshwater crayfish eats the bully. The eel (tuna) relies on the freshwater crayfish because he eats him, and if he wasn't there the eel would have no more food, than the eel would die. The eel and the duck connect because they both like shade. The bully and the mayfly connect because the bully eats the mayfly. The mayfly likes fast flowing water. Everything is connected to something else in some way, so we need to look after all of it.

Healthy or Unhealthy?


You would find macroinvertebrates in healthy water, but in unhealthy water, there would only be snails and worms or you may find nothing, because the water may be too warm. Why? Because macroinvertebrates like water that is 15 degrees or under.

Water temperature

The water temperature depends if the water is murky. If it is it would likely be 20 degrees celsius and over and if the water was clear it would probably be 15 degrees celsius or under.


Algae is a tiny plant that lives in the water. They create a slimy layer on the surface of rocks. Algae can be good or bad. If there is a big thick mat it is unhealthy, but if there a small thin layer it is good.


A variety of depths and flow rates provide a greater range of habitat types. Deep pools make good fish spawning areas. Rapids and riffles help oxygenate the water and make good habitats for invertebrates.

Submerged plants

Underwater plants are a vital part of the freshwater environment. They provide food and habitat for fish to live and breed and hide from predators. They also play an important role in keeping waterways clean and healthy.


Erosion is when dirt or sediment falls into our rivers

and creeks, lakes and more, making waterways unhealthy.


Our class visited many waterways in Christchurch including Dudley creek, the stormwater drain behind our school and the Styx river. We used an “In-stream and Riparian Habitat Survey” to visually test the ecosystem. We also fished out macroinvertebrates using a technical retrieval device, also known as a sieve on a stick. We also tested how clean the water was by using turbidity tube. A turbidity tube is a long ttube that you fill with water and there is a disc in it. If you can see the disc into the end it is clean but if you can see very close it is bad, unclear and unhealthy water.


The stormwater drain behind Waimairi school is unhealthy. This is because there is no shade over the waterway. If there were trees and shrubs it would be colder but there are no trees and shrubs so macroinvertebrates will not live there.  

75% of the stormwater drain has hardly any stones. This is bad because it has no hiding spots for macroinvertebrates and they can't breed.

As well as this the sides are very unstable over the waterway, and half of the waterway is eroding or breaking. This is because there are no tree roots holding the bank together.

The stream also flows straight and at one depth with no variety. This is bad because animals like the mayfly like fast flowing water.


Suggested changes

Although there are parts of the waterway ecosystem that are unhealthy, there are many changes we can improve its health.

  • plant trees and shrubs to give the waterway shade. And hold the bank together.

  • Replace the dirt and put stones in so macroinvertebrates can hide and breed.

Why these changes are important  

These changes are important so we can swim and play in

our waterways. No one wants to swim in a polluted river, and a lot of macroinvertebrates and fish and ducks will love making it a great place to be, like fish will search for macroinvertebrates. A lot of people will visit the stormwater drains like classes and other locals we see it daily because it is by a main footpath.

It is also important to look after our rivers because we want to respect kaitiakitanga. Kaitiakitanga is a Maori cultural value that means to protect and care for our land and water. We want people to be able to love our rivers in future so we need to keep them healthy.

1 comment:

  1. Gosh, what a lot of hard work and thinking has gone into this report Josh. You have learnt a lot this term. And what a stunning piece of writing (with a graph no less!) to sum up your learning. Great job.