Acoustic instruments are increasingly used to measure flow velocities and concentrations of suspended particles in aqueous environments. A recent development, the so-called horizontal ADCP, is an instrument which is installed at a fixed location in order to measure real-time horizontal current profiles. One application of these instruments is the continuous monitoring of river discharge. Data are presented from a study site equipped with three horizontal ADCPs operating at 300 kHz, 600 kHz and 1200 kHz during a seven-month period. Measurements of backscattered intensity and attenuation are compared to optical turbidity, which is a proxy for concentration, and water samples are analysed for particle concentration and grain size. A distinct linear relationship is found between sediment attenuation and turbidity for all instruments when concentrations are greater than ~100 - 500 mg/L, depending on the instrument. This implies that when concentrations are high, the sediment attenuation can be used to determine suspended sediment concentrations. Velocity measurements obtained with the horizontal ADCPs are compared to the mean cross-sectional velocity obtained using discharge data from a gauging station 15 km downstream. It is found that during periods of low velocity and low concentration, the 300 kHz and 600 kHz instruments underestimate velocity. The 1200 kHz instrument is found to provide the most reliable measurements of velocity at our study site.