As shown in the Level I data summary graphs for Pine Lake, Level I data were collected beginning in October 1997 through September 1998 by Kate Bradley. During this monitoring year, lake surface temperature averaged 14.7°C. Lake level fluctuated by 0.64 meters throughout the year, increasing steadily throughout the wet season and declining in spring and summer. Total annual precipitation was 1,042 millimeters. Secchi depth averaged 3.8 meters. Water color was rated as 3.5 to 4.0 (yellow to green).

Level II data were collected biweekly from May through October of 1998 by Kate Bradley. The Level II data summary graphs for Pine Lake show Secchi depth, chlorophyll a, total phosphorus, and total nitrogen measurements. Based on this seasonal data collection, summer Secchi depth averaged 4.4 meters. Chlorophyll a concentrations averaged 3.1 µg/L, reaching a high of 7.2 µg/L in early September. In general, blue-green algal (Microcystis, Anabaena, and Aphanizomenon sp.) were the dominant phytoplankton types in Pine Lake. Summer total phosphorus concentrations averaged 10.0 µg/L, while total nitrogen concentrations averaged 364 µg/L.

Water quality data collected in 1998 is consistent with the previous two years. Based upon this seasonal data, water quality of Pine Lake is characterized borderline mesotrophic-oligotrophic, meaning it has moderate to low biological activity. The nitrogen to phosphorus ratio of 36 indicates that phosphorus levels limit algal growth. The volunteer observed local accumulations of algae in the form of streaks, surface blooms, and scum in the cove near her home throughout the year, however, algae concentrations (measured as chlorophyll a) at the center of the lake were low throughout the monitoring season.

The lake data were compared with one standard deviation (shaded area) about the median value of the combined data collected for all Level II participating lakes. For the most part, Secchi depth, chlorophyll a, total phosphorus, and total nitrogen values fell within the low end or below those values observed on other lakes in King County.