Indicators: Salinity

What is salinity?

Salinity is the dissolved salt content of a body of water. It is a strong contributor to conductivity and helps determine many aspects of the chemistry of natural waters and the biological processes within them. Salinity, along with temperature and pressure, helps govern physical characteristics of water such as density and heat capacity.

Why is important to measure salinity?

Estuarine systems: 

Estuaries are water bodies where rivers meet the sea. Because of the influence of the ocean, salinity is a normal part of estuarine systems. Salinity influences the types of plants and animals that live in different parts of an estuary. Less salt tolerant organisms are more likely to be found upstream in an estuary where the salinity is lower, while more salt tolerant organisms are found closer to the ocean where salinity is higher.  Changes in salinity levels in estuaries may be produced by climate impacts or other factors. For example, periods of excess rainfall can cause freshwater to extend further downstream into the estuary than normal, while periods of drought can cause elevated salinity levels to reach further upstream than normal.  Either of these weather events can lead to harmful effects on plants, animals and other organisms living in estuaries. 

The National Coastal Condition Assessment uses salinity as one of the primary factors to identify whether sites are "estuarine" as defined in the National Aquatic Resource Surveys.  

Freshwater Systems: 

Salts can be toxic to freshwater plants and animals and can make water unsafe for drinking, irrigation and livestock watering. Excess salinity can occur in areas where evaporation is high and made worse by repeated use of water for irrigation or water withdrawals, where road de-icers are applied and in mining, oil and gas drilling and wastewater discharges. 

What can salinity tell us about the condition of the water? 

Salinity can be a stressor in the aquatic environment as fluctuating levels of salinity can affect aquatic biological organisms which are adapted to prevailing salinity concentrations.   

How is this indicator used in NARS? 

The National Coastal Condition Assessment collects salinity data. Data are available on the NARS data page. Below the table you access assessment information in current reports. 

NLA	NRSA	NCCA	NWCA
		X

*Salinity is the total concentration of all dissolved salts in water and is a strong contributor to conductivity which measures the waters capability to pass electrical flow. Read more about Conductivity

National Coastal Condition Assessment Web Report – Coming Soon.