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What are algae? Algae are plant-like aquatic organisms, many of which are single-celled, but others grow in mats or filaments. Algae are the basis of most aquatic food webs, they produce oxygen to the atmosphere, absorb nutrients and can be a good indicator of water quality.

What do we mean by 'state'? On LAWA, we use the term 'state' to describe the current condition of a lake for a given water quality indicator. 

What do we mean by ‘trend’? A trend is a long-term, overall change in data in a consistent direction. Trends help us understand how water quality indicators behave over time, and whether conditions are improving or degrading. In river and lake water quality, a trend shows if measured values have gen...

Chlorophyll a is the green pigment in plants and algae that is used for photosynthesis. Measuring how much of this pigment is in the water provides a good indicator of the total amount (or biomass) of algae in a lake.  View a factsheet on Algae and Cyanobacteria in Lakes.

The Trophic Level Index (TLI) is a method of characterising the ecological health of lakes based on the amount of nutrients and algae growing in them.  It provides an integrated measure of water quality that can be tracked over time and that can be used to estimate biological productivity.  It is pr...

New Zealand Lakes Lakes are localised bodies of water that are surrounded by land. They may be fed by, or feed into rivers or may be maintained by rainfall and groundwater inputs. Lakes exist in all shapes and sizes and may be natural (for example formed by glaciation or landslides) or man-made (for...

What are marine algal blooms? Algal blooms can appear in the marine environment when weather conditions like wind and water currents are favourable. Areas with slow water circulation and high water temperatures can often experience bloom events. Algal blooms are comprised of algae, or aquatic plants...

Most estuary monitoring is carried out by regional councils and unitary authorities, who are responsible for managing the sustainable use of natural resources in their region and have a duty to gather and record information on the State of the Environment (SOE).  Other agencies that undertake monito...