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In most Minnesota<br />

lakes, phosphorus is the least<br />

available nutrient <strong>and</strong> thus<br />

high or low concentrations<br />

can have a major effect on<br />

total lake quality. Increased<br />

levels of phosphorus from<br />

wide ranging sources such<br />

as sewage treatment plants,<br />

lawns, or farml<strong>and</strong> runoff<br />

can trigger additional algae<br />

growth reducing water<br />

clarity. Combined readings<br />

of phosphorus, chlorophyll<br />

a (algae abundance), <strong>and</strong><br />

secchi disk transparency<br />

were used to define the<br />

trophic status index (TSI),<br />

or level of lake growth for<br />

both Sylvan sample sites.<br />

Figure 19. Water sample locations at Sylvan Dam Reservoir on<br />

Crow Wing River, Camp Ripley, since 2008.<br />

Final results of<br />

water testing reveal that<br />

Sylvan-North (ID# 49-<br />

0036-02) <strong>and</strong> Sylvan-Main<br />

(ID# 49-0036-01) contain<br />

higher than projected total<br />

phosphorus (Figure 20),<br />

which indicates poorer than<br />

expected water quality for<br />

the area. The total<br />

phosphorus mean (2008-<br />

2009) for Sylvan-North is<br />

31.5 ug/L <strong>and</strong> the 2009<br />

levels were below this mean. Sylvan-Main‟s levels of total phosphorus, chlorophyll-a, <strong>and</strong> Secchi<br />

depth were all higher than expected, which also indicates poorer than average water quality for lakes<br />

in the Northern Lakes <strong>and</strong> Forests Ecoregion. The Sylvan-Main total phosphorus mean (2008-2009)<br />

is 60.1 ug/L <strong>and</strong> 2009 levels were below this mean. The differences for this trend in water quality can<br />

be related to the width of the two areas. Sylvan-Main, being the confluence of the Crow Wing <strong>and</strong><br />

Gull rivers is wider <strong>and</strong> shallower than Sylvan-North <strong>and</strong> consequently experiences additional aquatic<br />

plant <strong>and</strong> algae growth during the summer months.<br />

Page 31<br />

2009 Conservation Program Report

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