Lake Management Plan

go to PGOLID main pageChapter 1 includes an introduction and abstract
Chapter 2 includes the goals of PGOLID
Chapter 3 history covers geological formation to current district projects
Chapter 4 covers watershed characteristics of most of northwest Minnesota
Chapter 5 covers the main watershed around the Pelican Lakes
Chapter 6 covers the minor watersheds that surround Pelican Lake
Chapter 7 describes the types of data collected and why
Chapter 8 reports the data and water quality of inlets and outlets to Pelican Lake
Chapter 9 reports the water quality data for the Pelican Lakes

Chapter 10
Chapter 11 Safety and Buoys

 

Questions?
PGOLID Water Resource Coordinator
218-846-1465, email

Chapter 9: Lake Water Quality

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Little Pelican Lake Trophic State Index

Little Pelican water quality at site 202 has been monitored from 2003 to 2007.

Results show that the overall average TSI for Little Pelican Lake is 47. This TSI is the highest in the Pelican Group of Lakes. It is highest because the Pelican River contributes a large amount of phosphorus to the lake.

For recreation, the lake is fairly usable most of the year. There may be some heavy algae blooms and plant growth in late summer.

The resulting numbers from secchi depth, chlorophyll-a, and total phosphorus measurements cover different units and ranges and thus cannot be directly compared to each other or averaged. In order to standardize these three measurements to make them directly comparable, we convert them to a trophic state index using an equation. You can find the equations online at: http://dipin.kent.edu/tsi.htm.

The overall trophic state index (TSI) of a lake is the average of the TSI for phosphorus, the TSI for chlorophyll-a and the TSI for secchi depth; therefore, it can be thought of as the lake condition taking into account phosphorus, chlorophyll-a and secchi depth.

It is important to understand that Trophic States are defined divisions of a continuum in phosphorus and algal concentration. more information on trophic state index

2008 Results

In 2008, Site 202 was monitored for water transparency, chlorophyll-a and total phosphorus. From these measurements, the Trophic State Index was calculated. The 5-year average TSI is 47; therefore, the average for 2008 was slightly higher than the historical average.

Table 1. 2007 Trophic State Index results.
Site Mean TSI Total Phosphorus TSI Chlorophyll-a TSI Secchi TSI
202 48 47 50 47

Historical TSI values: 2003-2008.

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© Copyright 2007 Pelican Group of Lakes Improvement District