Turbidity is a measure of water clarity which expresses how much light passes through the water column. It is dependent upon the amount of suspended particles (e.g., sediment, algae, bacteria) and colored organic matter present. Clear water is critical for the growth and survival of fish, crabs, and other aquatic organisms.

How is it measured?

Guanabara Basin

Turbidity was measured at approximately 55 stations between 2013-2015. The proportion of time that turbidity was below the threshold at each station was calculated and then spatially averaged into reporting regions.

Data is provided by INEA.

Each sample is compared to a threshold to calculate a score from 0 to 100. All sample scores are averaged for each sampling location to reach a station score. All stations in each region are averaged to a region score. All regions are averaged to the overall indicator score.

Threshold Levels

The turbidity threshold for the Basin is 10 NTUs (Nephelometric Turbidity Units). The turbidity threshold was determined using the US EPA and Mid-Atlantic Tributary Assessment Coalition (MTAC) protocol documents.