Water quality sampling methods may bias evaluations of watershed management practices

Area of Science:

• Environmental Science
• Hydrology
• Water Quality Monitoring

Background:

• Accurate measurement of total suspended solids (TSS) discharge is difficult due to temporal variability during high stream flow.
• Current sampling frequencies can impact the accuracy and precision of TSS load estimations and sediment retention assessments.
• There is a need for optimal sampling strategies that maximize accuracy while minimizing effort.

Purpose of the Study:

• To investigate the impact of sampling frequency on TSS load and retention estimations in a restored stream.
• To assess the effect of sampling frequency on TSS load estimations using long-term turbidity data.
• To identify the most accurate and economical sampling method for water quality monitoring.

Main Methods:

• Studied the effect of sampling frequency on TSS load and retention estimates in a Maryland stream.
• Synthesized 28 years of continuous turbidity-based TSS data from Europe and North America.
• Evaluated different temporal sampling frequencies and their impact on data accuracy and precision.

Main Results:

• Coarser temporal sampling methods can lead to inaccurate conclusions regarding restoration efficacy and sediment retention.
• Flow-paced composite sampling emerged as the most accurate and precise method for TSS load estimation.
• This method requires analysis of only one sample per week, offering significant cost-effectiveness.

Conclusions:

• Sampling frequency significantly influences the accuracy of TSS load and sediment retention estimates.
• Flow-paced composite sampling provides a reliable and economical approach for standardizing water quality monitoring.
• This method can improve the assessment of watershed health and restoration success.