Widgeon grass, which is tolerant of a wider range of 
salinities is usually found from the Bay mouth to the 
Susquehanna flats. 
SAV systems in the Bay have been marked by a series of 
distinct oscillations with both desirable and undesirable 
species changing over time. Fragmentory evidence indicate that 
until recently, SAV has been a widespread feature of the Bay's 
shallow water bottom, although its past has been marked with 
some specific fluctuations in abundance. 
The decline of eelgrass in the lower and middle sections of 
the Bay during the 1930s coincided with its worldwide decline. 
Eelgrass gradually returned over the next 30 years until the 
more recent period of decline in the 1970s. 
Several other species considered to be nuisance forms also 
have fluctuated. Water chestnut created problems in the Potomac 
River in the 1920s and the 1950s with declines being attributed 
to local eradication programs. 
Watermilfoil expanded very rapidly in the Potomac River and 
in the Upper Bay in the late 1950s and 1960s, but was reduced in 
abundance by the 1960s. 
The recent decline of SAV, which affected all major species 
in all sections of the Bay, is a local phenomena as there are no 
widespread reports of SAV declines in other areas of the east 
coast. Loss of these important communities occurred in the 
1960s in the upper and middle Bay areas. 
Bay-wide decline of SAV accelerated in the 1970s and 
continued through 1980 with the most rapid declines occurring in 
1972 through 1974, especially after the occurrence of tropical 
storm Agnes. Sections of the Bay that once contained lush 
stands of SAV had either no SAV (e.g., Patuxent, Piankatank, and 
Rappahannock Rivers) or only remnant stands (e.g., Potomac and 
Upper York Rivers and Susquehanna flats). Many of these areas 
still contain little SAV through 1984, although there has been 
some encouraging signs or regrowth in several locations. There 
are still substantial beds of SAV, but these are primarily locat¬ 
ed in the Lower Bay area. Areas in the Lower Bay, in close prox¬ 
imity to SAV stands that persisted through the 1970s, are ap¬ 
parently being revegetated by natural processes, primarily by 
seeds that are transported from adjacent vegetated areas. 
60 
