City of Lake Elmo Forester Karen Widin studied the forests in SLP in 2011, and Steve Kunde was contracted to do a followup in 2015. Although the plans were not adopted by the City, Their findings and recommendations are provided in this report:
Sunfish Lake Park has been impacted by pollutants which had been originally deposited when the County allowed dumping of waste for under $1 per cubic yard in 1969-1973 in the unlined Washington County Landfill, which had been a gravel pit and still had water in it when dumping began. Over the years various actions were done which failed to contain the leached pollutants. The Valley Branch Watershed District reports on Project 1007 provide detailed historical information on this matter.
The Minnesota Department of Natural Resources has sponsored a program of lake monitoring over the years, where citizens report data like the turbidity of the water. Here is a link to that information for Sunfish Lake.