The U.S. Army Corps of Engineers, Tulsa District, conducts routine operational water quality monitoring on select lakes annually. This usually includes three lakes selected and sampled annually based on a historical rotation schedule. The Tulsa District operates 38 projects with 31 of the projects part of the water quality monitoring rotation. This rotation allows for each project participating in the operational water quality monitoring program to be sampled at least once every 10 years. The purposes of the investigations are to collect sufficient water quality data to define existing limnological conditions, provide a basis for future water quality investigations, and support operational and environmental missions of the Tulsa District. Parameters are sampled monthly for six months during the months of April through September. Samples are gathered at predetermined historical site locations throughout each lake. Sampling locations are strategic to each project but usually includes riverine locations on the upper reaches of each project and its tributaries, transitional zones, open water locations throughout the lake, and below the dam as water leaves the reservoir. Field measured parameters at each site includes vertical profiles of water temperature, dissolved oxygen, pH, specific conductance, and Secchi depth. Water samples for laboratory analysis are also collected and usually include parameters such as alkalinity, ammonia, nitrogen, total suspended solids, total dissolved solids, total organic carbon, total and ortho phosphorous, chloride, sulfate, hardness, metals, chlorophyll a, total and dissolved silicon, and biologicals such as zooplankton and phytoplankton. Summary reports are drafted each year for individual lakes sampled the previous year and will be updated annually.  With any field activity variations of the water quality monitoring program can occur from year to year and even month to month. Flooding or severe weather conditions could alter or delete sampling periods for certain locations during flood years. Resource restraints such as equipment breakdowns, personnel, laboratory, and budget limitations can also have impacts on the program. For these reasons water quality data will often vary from lakes and years sampled. If further water quality data or information is desired, please contact the Tulsa District, Operations Division, Natural Resources Management Branch at 918-669-7370 or at CESWT-OD-NR@usace.army.mil.