NOAA’s National Ocean Service (NOS) Center for Operational Oceanographic Products and Services (CO-OPS) is pursuing a sole-source purchase from In-Situ Inc. of Fort Collins, CO for Aqua Troll sensors and parts on In-Situ’s GSA contract. The sole-source determination is based on NOAA’s requirement that Aqua Troll sensors are unique, with no alternative instrument found to meet specifications; the Aqua Troll 200 was previously approved after testing for conductivity, temperature, and level sensing. The purchase will support maintenance at stations in CO-OPS PORTS networks throughout the United States and emergency response CURBY systems for Gulf of America events. Implementing a different sensor would add cost and resources, delay testing/training/support-equipment purchases, and affect continuous operation of these systems.