Lake Management Plan
|
 |
 |
 |
 |
 |
 |
 |
 |
Questions? |
back to main Pelican Lake page
Pelican Lake Water Transparency
more information water transparency
Pelican water transparency at site 206 has been monitored from 1996 to 2008, and has an average 12.5 feet. A trend analysis showed that there is an improving trend in the data over this 13 year period, meaning that the Secchi readings are getting better over time.
2008 Results
In 2008, all three lake sites were monitored for water transparency with a Secchi disk. The results were all very similar. From these results, we can conclude that the water transparency is fairly uniform across the entire lake. The 12-year average Secchi depth is 12.5 feet; therefore, the average for 2008 was greater than the historical average. For results from each individual site, please see below.
Table 1. 2007 Secchi depth results.| Site | Mean Secchi Depth (ft) | Min Secchi Depth (ft) | Max Secchi Depth (ft) |
| 201 | 13 | 9 | 17.5 |
| 206 | 14.1 | 9 | 23.75 |
| 205 | 12.2 | 8 | 19.5 |
Site 206
Site 206 has been monitored from 1996 to 2008.
Tracking trends in data over several years can indicate improving or declining water quality. Generally, it is best to have 8-10 years of data with 4 or more measurements per year to be confident in an emerging trend. Statistically, the probability that a trend is truly describing the water quality and not just a random trend is important. A probability over 90% is required by the MPCA to really be confident in the observed trend. This means that there is a 90% probability that the trend is a true pattern in the data and a 10% probability that it is a random pattern.
The probability that a true significant trend exists is 99% Secchi Disk is increasing, which indicates improving water quality. |
|
|||||||||||||||||||||||||||||
Site 201
Site 201 was added in 2007 to see if the water transparency was different on the west end of the lake due to two inlets. Bob Creek and Spring Creek both flow into Pelican Lake on that end. The average Secchi depth at site 201 in 2008 was 13 feet, which was less than site 206 and better than site 205. The secchi depth in 2008 was better than in 2007.
Site 205
Site 205 was added in 2007 to see if the water transparency was different on the east end of the lake due to the Pelican River inlet flowing through Little Pelican Lake. The average Secchi depth at site 205 was 12.2 feet, which was slightly less than sites 206 and 201. This is most likely because the Pelican River is the largest contributor of nutrients to the lake. The transparency was better in 2008 than 2007.
