Birchwood Lake is a spring-fed lake, which means the water is cold, clear, and stays that way through the summer. The clarity is about fourteen feet on a calm day, which means you can watch the sandy bottom from the dock and see the occasional northern pike moving through the weed edge. Swimming here is not like swimming in a pool or a warm southern lake. It is better, in my opinion, but it takes a day to adjust.
Water temperature by month ¶
May: 48 to 55 degrees. Brave guests swim. Most do not. June: 58 to 66 degrees. Wading is comfortable, swimming is possible, especially in the afternoons. July: 68 to 74 degrees. This is the sweet spot. The water is warm enough to swim comfortably for an extended time. August: 70 to 75 degrees, sometimes higher in a hot summer. September: drops back to the low 60s by mid-month. October: 50 degrees and below. A few guests swim in October. They are a specific type of person.
The swim area and what it looks like ¶
The swim area is roped off about forty feet out from the main dock. The bottom is sandy and gradual, dropping from about two feet at the shore to six feet at the rope. There are no rocks in the swim area. The dock itself has a ladder on the east side for getting back in the water after jumping off. The water is clear enough that you can see the bottom from the dock on most days, which children find immediately fascinating and adults find quietly reassuring.
The spring-fed clarity and what it means ¶
Birchwood Lake is fed by several cold springs on the north and east ends. This keeps the water temperature lower than a comparable lake without springs, and it keeps the clarity high because the springs flush the water continuously. There is no significant algae bloom on this lake in a normal summer, which is not something you can say about every Minnesota lake. The water is not treated or filtered. It is just cold and clean.
What people always ask about: leeches ¶
Yes, there are leeches in Birchwood Lake. There are leeches in every Minnesota lake. They are most active in the shallow, weedy areas on the north end of the lake, not in the swim area. In seventeen summers, I have seen a guest come out of the swim area with a leech attached twice. Both times it was a small one and both times it was fine. The swim area is sandy-bottomed and relatively open water, which is not leech habitat. This is not a leech lake. It is a normal Minnesota lake.
The lake is the reason most people come here. Give yourself one full day to adjust to the temperature and the pace of it, and by the second day you will not want to leave.