I grew up in Silver Spring (Woodmoor) in the '60s and the NW Branch at the Burnt Mills Dam & Reservoir and Camp Wilson - a pre-suburbia Boy Scouts'Camp (the swimming hole at the beautiful rock gorge downstream) - was our Tom Sawyer-like playground.
We often found cement tubs - I guess somebody swiped them from construction sites - which were excellent rafts. We became "pros" at paddling and even fabricated crude paddles out of old plywood. (Our basements always had great supplies of scrap wood).
In winter, the reservoir regularly froze to allow several weeks of ice skating and pickup hockey (with no protective gear!). Those were the days of kids doing risky outdoor behavoir: no signs or police kicking us off!
Big excitement (for us 16 year olds) occurred during the '72 Tropical Storm Agnes when water poured over the Route 29/Colesville Road bridge: nobody hurt but it was interesting to watch the WSSC cars float downstream!
Pete
(correlates: StreetScene, RighteousRage, OnBooklessness, ...)