Freezing changes the values of turbidity

Abstract Turbidity is a common measure to evaluate the clarity of wetlands, rivers, lakes, and reservoirs. We lack information on whether turbidity samples collected from the field are viable after freezing and thawing. Our goal is to understand the degree to which freezing and thawing water samples alters the value of turbidity compared to fresh samples. Water samples from wetlands, and streams near Laramie, Wyoming were collected during May 2023. We collected paired samples by comparing turbidity values of freshly collected water to samples that were frozen prior to analysis. Fresh and frozen turbidity measurements differed. Freezing altered particle stability causing aggregation or degradation, potentially explaining why some values increased and others decreased compared to fresh samples. Our findings suggest that freezing water samples prior to turbidity analysis will result in inaccurate measurements and is not recommended.