Clear Lake is a large, shallow, hypereutrophic lake in Northern California, USA. Clear Lake is an important water resource for the surrounding community offering many cultural and recreational opportunities and provides drinking water for more than half of the region's population. Despite these many ecosystem services, Clear Lake suffers from Harmful Algal Blooms (HABs) of cyanobacteria. This project aims to understand the lake and watershed processes contributing to the negative impacts on the lake water quality and ecosystem health with a goal of rehabilitating the lake. The UC Davis Tahoe Environmental Research Center conducted a 5-year (2019-2023) water quality monitoring program collecting monitoring data to better understand the physical, chemical, and biological processes affecting lake quality. Data from this monitoring program are publicly available through EDI at https://doi.org/10.6073/pasta/4f803082f7906f764994366a9e69c940. This project is funded by the California Department of Fish and Wildlife through California State Assembly Bill 707 (2017), the California Natural Resources Agency, and the UC Davis Tahoe Environmental Research Center. In addition to this overarching project, we completed additional biological and optical measurements over a shorter 1.5-year time period (Jul 2021 - Oct 2022) with the goal of supporting Phytoplankton Community Composition (PCC) and Cyanobacteria genera differentiation algorithm development from remotely sensed hyperspectral measurements. Three of these sampling events were completed coincident to whole-lake hyperspectral images collected by the DESIS sensor. These additional data included High-Performance Liquid Chromatography (HPLC) phytoplankton pigment data and above-water spectroradiometry (SVC HR-1024i) measurements. This additional work was supported by a NASA Office of STEM Engagement (OSE) graduate student fellowship awarded to Samantha Sharp in 2020 (Grant Number 80NSSC20K1458).