What a difference a year makes. Last year, February flows into the Bay were the highest on record. This year, flows were 34 percent below normal, according to figures from the U.S. Geological Survey.
The first six months of 1998 had the highest average flows for the first half of the year since the USGS began keeping records in 1951. But flows have been below average every month since last June.
Last February, flows into the Bay were 152.4 billion gallons a day. This year, the flow was 45.5 billion gallons a day; the average is 68.7 bgd.
This year’s February flows from the Potomac were particularly low, averaging 4 bgd, or 62 percent below the long-term average of 10.4 bgd.
Typically, flows into the Bay — after reaching their lows in late summer — begin increasing in October and continue the trend through the winter and into spring. But low flows have continued; December set a low-flow record for the month.
A possible consequence of continued low-flow conditions could be improved water quality, because smaller amounts of nutrients and sediment are carried into the Bay with the runoff. On the other hand, low-flow conditions increase salinity levels, which could encourage the growth of oyster diseases, increase the abundance of jellyfish in the summer and reduce the potential spawning habitat for migratory fish that spawn in freshwater portions of the Bay.
Real-time streamflow data can be found on the USGS Chesapeake Bay
web site at: http://chesapeake.usgs.gov/chesbay/