Silver Lake is fortunate that it does not have many of the invasive species that are now encroaching on native species in other lakes in NH and Hollis. For example, milfoil and water chestnut are not found in Silver Lake. This is most likely because there is no public boat launch, so few few boats are on the Lake.
However, the Chinese mystery snail (photo here), can be found in Silver Lake. Another semi-invasive found in the Lake is the common carp, but it is not a major concern. Sometimes, both of these species are introduced as a result of people dumping the contents of their aquariums.
Here’s a brochure from NH Lakes with photos of species invading NH lakes: https://nhlakes.org/wp-content/uploads/Lake-Host-AIS-Identification-2019-1.pdf
Be sure to clean off boats before entering Silver Lake, and do not add fish and plants to the Lake to keep it free of these problem species.