This protocol describes the rationale, objectives, sampling design, field and laboratory methods, data analysis and data management procedures for long-term monitoring of mountain lakes in the North Coast and Cascades Network (NCCN). Lake monitoring will occur at three NCCN parks including Mount Rainier National Park (MORA), North Cascades National Park Service Complex (NOCA), and Olympic National Park (OLYM). This prototol utilizes a cost efficient comprehensive approach, applying multiple indicators representing key physical, chemical, and biological attributes (Vital Signs) which will serve to address current management issues as well as future emerging issues at park-wide and region-wide scales.