Disruption of the landscape surface, whether from timber removal, surface mining, or gas and oil exploration, can cause erosion and the subsequent impairment of sensitive areas, such as streams or wetlands, or the reduction of beneficial uses that may include drinking water or recreational uses. Regulatory agencies often require permits that set limits for erosion, sediment delivery, or pollution loading, that call for monitoring to demonstrate compliance with state and federal regulations. In some cases the watershed may have additional restrictions from Total Maximum Daily Load (TMDL) limits related to sediment or mercury impairment, or the operations may be under the control of a Best Management Practices (BMP) document. To demonstrate that a particular operation is in compliance it may be necessary to determine the “background” level of turbidity or sediment loading. This can be difficult in landscapes that are heavily managed because a stable control watershed may not be available and comparisons may be limited to above and below the disturbance. Establishing a monitoring protocol and sampling locations before the commencement of activities is recommended, but not always practical.

The automated monitoring of turbidity and the collection of suspended sediment samples provides a reliable method for capturing important runoff events in rain-dominated watersheds because most of the suspended sediment load is transported during a few large infrequent storm events. Because it difficult to predict when storm events will occur traditional methods of sampling, such as weekly manual samples, are often inadequate to characterize the variability in suspended sediment concentration. Real-time turbidity is a reliable surrogate for detecting sediment pulses from road surfaces, gullies, landslides, or stream bank failures that are often not well related to water discharge. Turbidity Threshold Sampling (TTS) uses turbidity to automatically control the collection of pumped samples based on pre-established thresholds set by the user. The TTS sampling parameters can be optimized for each sampling site to collect on average between 3 to 10 pumped samples per storm event, or approximately 60 to 80 pumped samples per season. For long term projects the development of the sampling location and facilities is important for multi-season comparisons. For installation that are more temporary in nature, such as compliance monitoring, the Rapid Deployment Monitoring System provides a turn-key solution that can be easily be installed, and upon completion of the project it can be moved to a new location.