Light penetration through the water column is vital for the growth and survival of photosynthesising benthic habitats such as coral reefs and seagrass. Light attenuation by in-water components such as phytoplankton, suspended sediments and CDOM reduces the benthic photosynthetically active radiation (bPAR) available to these habitats. In situ measurements of bPAR are a common water quality parameter monitored by marine custodians to ensure the integrity of light-dependent habitats however, most monitoring programs measure overall bPAR without assessing preferential attenuation of different wavelengths of light in the water column. In turbid water, it is often the green-yellow light spectra that most reaches benthic habitats, however, this wavelength of light is the least useful for photosynthesising biota. Here, we present daily bPAR from multispectral (9 wavelength) irradiance sensors with concurrent turbidity (NTU) sensor data at locations with proximity to both industrial ports and coral/seagrass habitats across the Great Barrier Reef lagoon. We analyse the relationship between turbidity, light wavelength attenuation, bPAR and metocean processes, to evaluate when, and how much, Photosynthetically Useful Radiation (PUR) is reaching these benthic habitats.