This study is concerned with projections of climate change effects on lakes, especially
small lakes with surface areas up to 10 km2 and depths up to 24m in the cold regions of
the contiguous United States. For this study, we have chosen lake parameters which are
most directly influenced by climate and which in turn have much influence on aquatic
lifeforms, water quality and water uses. The two main parameters studied herein are lake
water temperature (T) and dissolved oxygen (DO) concentration. In the process, we have
also obtained information on evaporative water losses from lakes, ice covers on lakes,
sediment temperatures below lakes and fish habitat (as constrained by T and DO) in lakes.
To make such a broad study, we had to develop and apply process-oriented, simulation
models which link atmospheric conditions to lake water conditions. Before the models
were applied at the continental-scale in this report, the model formulations and
assumptions were reviewed to examine what geographically variable parameters had to
The models were applied to 27 types of lakes. The lakes chosen differed by surface
area, maximum depth and transparency as measured by Secchi depth. These three
parameters are known to have the largest influence on lake water temperatures and DO
concentrations. The Secchi depth was related to transparency as well as trophic state of
a lake. This is a major assumption which will not hold true in lakes which show turbidity
from inorganic suspended sediments. Secchi depth was related to mean annual
phytoplankton chlorophyll-a concentration in a lake. This made it possible to estimate
photosynthetic oxygen production without specification of nutrient inputs from the
watershed. Lakes were also treated as having constant volume and long hydraulic
US Environmental Protection Agency, Office of Research and Development
Fang, Xing; Stefan, Heinz G..
Effects of Past Climate Conditions on Lake Water Temperatures and Dissolved Oxygen.
St. Anthony Falls Laboratory.
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