Lake Winnipeg, located in Manitoba, is approximately 25,000 square kilometers and is the tenth largest freshwater lake in the world. The mean depth is approximately 12 m. Lake Winnipeg's water shed encompasses 4 provinces, 4 states and over 100 Indigenous Nations. Economic benefits include a $110 million tourism and recreation industry and a $25 million commercial and sport fishing industry. In recent years, excessive nutrients have led to increases in frequency and severity of cyanobacteria blooms. Phase I of the Lake Winnipeg Basin Initiative (LWBI) (2008-2012) was implemented to determine scientific gaps pertaining to sources and transport mechanisms for nutrients and asses ecology and nutrient cycling. Phase II (2012-2017) encompasses monitoring and further research on priority gaps and to measure results and effectiveness of cleanup efforts. Here we present data collected to support various efforts of the LWBI. For more information, please visit https://www.canada.ca/en/environment-climate-change/services/water-overview/comprehensive-approach-clean/lake-winnipeg/reports-publications/basin-initiative.html.