Turbidity and Suspended Sediment Concentration Data from a Laboratory Mixing Tank Experiment 2023 (ver. 1.1, November 2024)

Four dams on the Klamath River that created Iron Gate Reservoir and Copco Lake in Siskiyou County, California, and John C. Boyle Reservoir, in Klamath County, Oregon, are scheduled for removal in early 2024. The U.S. Geological Survey (USGS) will deploy high-range turbidity sensors to compute continuous suspended sediment concentration (SSC) before, during, and following the scheduled dam removals. SSCs in the Klamath River are expected to be extreme during the dam removal process because of mobilization of fine-grained sediments that settled in the upstream reservoirs. Extreme SSC values are unlikely to occur unless during an extreme event, and are difficult to predict. Therefore, the USGS did controlled laboratory experiments to simulate extreme SSC values to establish the upper limits of the turbidity-SSC rating being developed to estimate SSC and transport along the Klamath River during and after dam removals. The experiments used multiple field -deployed Observator Analite NEP-5000-180 backscattering turbidity sensors in custom observing ranges up to 10,000 SDVB (styrene divinylbenzene beads) Backscatter Units (SBU), a Sequoia Scientific LISST-ABS acoustic backscattering SSC sensor with an upper observing limit of 30 g/L, and a YSI EXO2 with turbidity probe with an upper observing limit of 4,000 formazin nephelometric units (FNU). Prior to the full-scale tank experiments, four experiments were done using bench-top equipment to test the effect of deionized water, tap water, and native water on the turbidity-SSC relation. Four experiments were done using a domed-bottom mixing tank with a range of SSC values from 0 milligrams per Liter (mg/L) up to 29129 mg/L.