Silver Lake is mentioned numerous times in the Little House series of books, from the book By the Shores of Silver Lake, through the remaining books in the series.
The lake was named by Laura’s mother, Caroline Ingalls, due to its silvery appearance.
SILVER LAKE (Kingsbury Co., dry, natural), 3 m. s. of DeSmet, was named by Mrs. C. P. Ingalls, one of the first settlers of DeSmet, because of its resemblance to a pool of silver when seen from a distance.
Silver Lake is most popular as being a location by Laura Ingalls Wilder, it is still a place you can visit today. When I was there, it was definitely more of a lake, but others have reported over the years that it is more of a slough or marsh. This depends on seasonal rainfall and how hot it is during the summer.
If you travel to De Smet, the lake could look like a traditional lake, or it could appear as more like a slough or marsh.
Also nearby are Lake Henry and Lake Thompson, which are also mentioned in the books.