Pickwick Reservoir

Ecological health rating

The overall ecological health condition in Pickwick Reservoir rated fair in 2008, with the lowest score (66) to date due primarily to chlorophyll and bottom life rating near the low end of their historic ranges at several monitoring locations. Conversely, the higher score in 2004 resulted from these indicators concurrently rating at the upper end their historic ranges. Pickwick, however, typically scores near (slightly above or slightly below) the break point between a good and fair rating. Year-to-year variation primarily depends on chlorophyll concentrations (which are affected by reservoir flows), and conditions in the Bear Creek embayment, which generally rates lower than at other monitoring locations on the reservoir.

Pickwick Reservoir Ecological Health Ratings, 1994-2008

Click chart for raw data.

The table below shows the ratings for individual ecological health indicators for Pickwick Reservoir in 2008. These ratings are briefly explained in the paragraphs that follow.

Monitoring locations	Dissolved oxygen	Chlorophyll	Fish	Bottom life	Sediment
Ecological Health Indicators for Pickwick Reservoir, 2008
Forebay	Fair	Poor	Fair	Fair	Good
Mid-reservoir	Good	Poor	Fair	Fair	Good
Bear Creek embayment	Good	Poor	Good	Poor	Good
Inflow (near Wilson Dam)			Good	Good
Dissolved oxygen Dissolved oxygen rated fair at the forebay and good at the mid-reservoir and embayment monitoring locations. This indicator usually rates good at the mid-reservoir location, but ratings have varied between good and fair at both forebay and mid-reservoir, generally in response to reservoir flow conditions. Chlorophyll Chlorophyll rated poor at the three locations monitored. Chlorophyll typically rates poor at the forebay and embayment locations and has fluctuated between poor, fair, and good at the mid-reservoir location. As with dissolved oxygen, reservoir flows have played a part in the year-to-year fluctuations as low-flow conditions tend to allow more time for algal populations to become established. v Fish The fish community rated fair at the forebay and mid-reservoir and good at the inflow and Bear Creek embayment monitoring locations. This is consistent with previous monitoring results. Fish community ratings generally have fluctuated between good and "high fair" ratings at all locations. Bottom life Bottom life rated good at the inflow location, fair at the forebay and mid-reservoir, and poor at the embayment location. Three locations — forebay, mid-reservoir, and embayment — received scores that were at lower end of the historical range because overall abundance and diversity of animals were lower. The lower ratings likely were the result of the low dissolved oxygen conditions that developed along the reservoir bottom in 2008. Sediment Sediment samples collected from the reservoir bottom were free of pesticides and PCBs, and concentrations of metals were within expected background levels, resulting in good ratings for sediment quality at all monitoring locations. See definitions of ecological health indicators and monitoring locations.