Gunpowder Falls

Here is how to calculate whether you will have enough water. a)Check whether Loch Raven Reservoir is full -- it normally stays full if the inflow exceeds about 150 cfs; b)If it is full, add the gauge readings on the Gunpowder (at Glencoe), Western Run and Beaverdam Run. They should total at least 350-375 cfs in the winter and spring, 400 cfs in the summer (when there is more evaporation and more water drawn from the reservoir for lawns). c) If it is not full, forget it. d) It takes about 2 days (at low levels) for that water to get to this section -- so, for example, Thursday's reading will tell you whether you will have enough water on Saturday; e) Above those totals, you get about 1 inch for every 40 cfs, for the first foot or so. After that, each inch requires more cfs, but I haven't worked out the formula.