The program's design allows state objectives to be met and ensures various-sized waterbodies are represented adequately. Large lakes (>500 surface acres) are sampled twice in non-consecutive years, while smaller lakes (50-500 surface acres) are sampled once. The number of sampling stations per lake varies depending on lake size and morphology. In general, 3-5 stations were chosen per lake in order to be representative of the riverine, transitional and lacustrine zones of the waterbody. On many reservoirs, additional sites are monitored, including major arms of the reservoir as appropriate.

Surface water quality samples are collected to determine concentrations of various nutrients, minerals, metals, and turbidity. During periods of stratification, additional bottom samples are collected and analyzed. Biological indicators include chlorophyll-a, phytoplankton, and zooplankton. Bacteria sampling occurs during the recreation season of May through September on a limited basis. Vertical profiles for dissolved oxygen (DO), % DO saturation, temperature, pH, salinity, oxidation-reduction potential (ORP), specific conductance, and total dissolved solids (TDS) are recorded at one-meter intervals from the lake surface to the lake bottom at each location. Readings for secchi disk depth and nephelometric turbidity are also taken at all sample stations. Additional water quality parameters have been added to the lakes sampling effort over the years to enhance the ability to make use support determinations. An assessment of physical habitat for each lake is conducted at least once during the five-year rotation.

Lake Arcadia appears on the 303(d) list for several impairments related to turbidity and chlorophyll-a; however, these impairments have not been definitively documented. Data collection is designed to assist in identifying the source(s) and extent of Lake Arcadia’s impairments. The specific objectives of the project include the following: (1) establishing if Lake Arcadia is currently meeting its assigned beneficial uses, (2) determining the extent of impairments, (3) providing data for TMDL development, (4) gathering historical data (if available) to be used in Phase 1 of the TMDL process, and (5) gathering data to characterize the watershed.

Lake Thunderbird, an important water supply lake serving several metro communities, has suffered increased eutrophication due to nutrient loading. The OWRB provides additional monitoring and assessment of the lake's super saturated dissolved oxygen system, the SDOX, to identify any direct effects on lake processes. The most recent water quality report for lake Thunderbird can be found here.