Pawtuckaway Lake changes with the seasons, with environmental and ecological influences, and with shifts in weather patterns, not to mention human intervention.
You can follow and learn about changes to lake water levels here.
Just because there is a notice on the State Park sign that says “Beach Closed” doesn’t mean that the lake water is unsafe for swimming. It usually designates maximum capacity at the beach area of the State Park which means it has been closed to additional visitors.
The NHDES Beach Program monitors the quality of water at various NH Beaches. You can check on conditions at the two Pawtuckaway Lake beaches by looking at State-issued advisories here.