Pre- and post-construction water quality monitoring for Habitat Rehabilitation and Evaluation Projects at Big Lake Bay, Finger Lakes, Lake Onalaska, and the Pool 8 islands area of the Upper Mississippi River

Continuous dissolved oxygen and temperature readings were taken
along with early morning readings in Big Lake Bay, Finger Lakes,
and the Pool 8 Islands area to document and provide preproject
data on each location. Similar readings were taken in Lake
Onalaska to provide postproject data.  Sampling took place from
August 13 through September 5, 1990.  All sites displayed daily
fluctuations in dissolved oxygen and water temperature.  Daily
variation in dissolved oxygen and temperature relate directly to
the daily weather conditions.  Overcast, cloudy days have less
fluctuation in dissolved oxygen and temperature than do sunny
days.  Density of aquatic vegetation and lake size also influenced
the extent of variability in dissolved oxygen, with  sites having
a large surface area and low plant density showing more stability
than sites of small area and high macrophyte density.  This is
presumably due to the effects of mixing and photosynthetic
activity.