Monitoring Reports

The recent rainfall in the Potomac basin, averaging ¼ inch, has not significantly changed streamflows. Operation of hydroelectric dams on the Potomac River, Dams 4 and 5, are resulting in high peaks and low troughs in flow, which are visible at the USGS Potomac River streamflow gages at Shepherdstown, Point of Rocks, and Little Falls. A flow peak is currently at Little Falls, but we expect a trough to arrive at water supply intakes and at Little Falls late tomorrow.

Today we are initiating CO-OP Drought Operations, per the Water Supply Coordination Agreement (WSCA) of 1982. According to the WSCA, Drought Operations is triggered when flow in the Potomac River at Little Falls, plus Washington metropolitan area Potomac withdrawals, “is projected to be less than twice the projected withdrawals for any of the next five days.”

Potomac River flows continue to slowly decline. A modest amount of rain is in the Middle Atlantic River Forecast Center’s 3-day forecast, ranging from ¼ to ¾ inch across the basin, and slightly more is predicted in the 7-day forecast.

No rain fell in the basin over the past 24 hours.  Rainfall is expected over the next 3 days according to the Middle Atlantic River Forecast Center, ranging from 0.1 to 1 inch.  The National Weather Service’s 7-day forecast predicts additional rainfall over the course of the next week, with 7-day totals up to 1 ¼ inches in some areas.  

Potomac River flows continue to slowly decline. A modest amount of rain – ranging from 0.1 to 0.5 inches – is expected in the basin over the next 3 days according to Middle Atlantic River Forecast Center forecasts.

Over the last 24 hours, no precipitation has been recorded in the basin. No significant rainfall is expected over the next 72 hours.

Potomac River flows continue to fall. National Weather Service forecasts indicate that no rain will fall in the basin over the next three days.

Potomac River flows at Little Falls have been relatively steady for the past few days. The USGS conducted two field discharge measurements at Point of Rocks over the course of the past few days and adjusted flow values accordingly.  No rainfall is expected in the basin over the next three days.

CO-OP is reinitiating daily drought monitoring and reporting today because Potomac River flow at the US Geological Survey’s stream gage at Point of Rocks, Maryland, is approaching the 2000 cubic feet per second (cfs), CO-OP's daily monitoring threshold. According to the Middle Atlantic River Forecast Center, no rainfall is expected in the basin over the next three days.

CO-OP is suspending daily drought monitoring emails because flow at the US Geological Survey’s gage at Point of Rocks, Maryland, has risen above the 2000 cfs monitoring threshold. Yesterday, a tornado watch lasted until 9 p.m., but there were no confirmed tornadoes in the region. Some parts of the basin observed up to 1.75 to 2 inches of precipitation during this time. The Middle Atlantic River Forecast Center predicts an additional 0.1 to 1.25 inches of rainfall over the next 72 hours, possibly arriving by this Thursday.