According to this study, a comprehensive and cost-effective method for wide area detection and monitoring of harmful algal blooms is needed to manage--and where possible circumvent--the negative impact harmful algal blooms may have on the country"s aquatic ecosystems. This study focuses on the performance of a low-cost, in-house developed prototype radiometer, which was evaluated against data registered with a commercially available hyperspectral tethered spectral radiometer buoy during a field campaign at Loskop Dam in South Africa.