What are the causes and consequences of water quality 'issues'?

Water quality management is complex and it is best to simplify the process whenever possible. Managers often use conceptual models to better understand and communicate complex water quality issues. The conceptual approach to managing water quality comprises three main components: the identification of (i) causal pressures on a waterway; (ii) the stresses that can result from causal pressures; and (iii) environmental values (EVs) and uses that could be impacted upon. Theoretically, indicators can be developed for all three of these components.

Causal pressures

Causal pressures or “threatening processes” are the driving forces behind changes in waterways. Causal pressures often result from human activities and uses, although natural climate change and natural disasters can also constitute causal pressures or ecosystem forcing functions. The Natural Resource Management community in Australia recognises five common areas of human-related causal pressures for management:

Industrial point sources;
Urban stormwater;
Rural land use and management change;
Flow alterations; and
Riparian habitat removal (e.g. mangroves)

However, causal pressures can encompass a range of different levels, e.g. from population density, to number of nutrient point-sources, through to pollutant concentrations. The inherent breadth of the causal pressures concept has been a source of confusion for many. It was for this reason that the "in-stream-pressures" or "stressors" terminology was developed.

Information on 15 stressors that impact Australian coastal waterways.

Consequent in-stream pressures/stressors

From an ecological perspective, a stress is a change that causes a response in a system or population of interest. In the context of environmental management, in-stream pressures or stressors are the stresses that directly impact upon a system. Stressors generally result from causal pressures.

Information on 15 stressors that impact Australian coastal waterways.

Impacts on values/uses

This component describes the status of the environmental values that management is trying to protect. environmental values fall into four broad categories:

Aquatic ecosystems
Primary industries
Recreation and aesthetics
Drinking water

The aquatic ecosystem category has four key components:

water (and sediment) quality;
habitats
flow
physical form (geomorphology) and
biota

Additional resources

Proforma sheet can be used to identify and record your initial qualitative assessment of your waterway, to be used in conjunction with example sheet (PDF 99KB, © Coastal CRC ).