Light attenuation in large scale neutrino detectors like Theia is an important concern. Theia plans to use Water Based Liquid Scintillator as its detecting medium. At UC Davis, we develop a Scattering and Attenuation Measuring Device(SAMD) to measure light attenuation as well as the scattering parameters of the WBLS. The poster will present the initial pure water attenuation result to show the reliability of the system. A future update plan of light attenuation and scattering in WBLS will be discussed as well.