A trophic state analysis of selected lakes and ponds in Yellowstone National Park

Albrecht, Bryce

Since 1998, Dr. A. Woodruff Miller has been sampling lakes and ponds in Yellowstone National Park. In 2010, 40 lakes and ponds were sampled of the 47 total that have been sampled since 1998. Each lake was assigned a trophic state classification based on the lake's transparency, chlorophyll-a concentration and phosphorus concentration. The trophic state classification identifies the degree of eutrophication that has taken place or the amount of organic material being supplied to the ecosystem. The degree of eutrophication can therefore be utilized to establish the health of a lake or pond. The purpose of this report is to classify the lakes sampled in 2010, observe any variations in the rate of change of eutrophication, and to compile all data collected since 1998. Four models were utilized to classify the lakes sampled-the Carlson Model, the Burns Model, the Vollenweider Model, and the Larsen Mercier Model. Each model was used to classify the lakes sampled in 2010, determine an overall average trophic state classification and any increase or decrease in the rate of change of eutrophication. In 2010, there were 4 lakes classified as Slightly Oligotrophic, four Slightly Mesotrophic, five Mesotrophic, seven Strongly Mesotrophic, seven Slightly Eutrophic, six Eutrophic, five Strongly Eutrophic, and two Hyper-eutrophic. Over time, two lakes decreased in trophic state, four slightly decreased, nine did not display any change, 12 slightly increased, nine increased and four that could not be determined because the lake had only been sampled once. The healthiest lakes would be classified as Slightly Oligotrophic; Duck Lake, Eleanor Lake, Lewis Lake, and Yellowstone Lake at West Thumb. The lakes that would be considered the least healthy are classified as Hyper-eutrophic; Hot Beach Pond and Trumpeter Pond.