The distribution of submerged aquatic vegetation (SAV) in Chesapeake Bay, its tributaries, and the coastal bays of the Delmarva Peninsula, was mapped from 1,857 black and white aerial photographs. These were taken between May and October 1999, at a scale of 1:24,000, encompassing 160 flight lines covering 2,135 miles of shoreline.

CHESAPEAKE BAY

For 1999, 26,190 hectares (64,689 ac) of SAV were mapped in Chesapeake Bay and its tributaries. (Figure 1) However some portions of the Bay were either flown too late due to poor atmospheric conditions and severe fall storm events or were not flown until after an early seasonal die-back in freshwater SAV species, possibly a result of increased salinity and the fall storm events. These regions, including Spesutie Narrows, Bush River, Gunpowder River, upper Patuxent River, lower Magothy River, the Swan Point and Tavern Creek region, upper York River, and upper James River, which in 1998 had 1,553 hectares of SAV (3,835 ac, 6% of the 1998 total), were not fully mapped for 1999.

In order to ensure a valid analysis of change in SAV distribution and abundance, given the reduced region mapped for 1999, all direct comparisons to previous years in the report are restricted to only those regions that were mapped in both years. Partial totals for 1998 have been computed for CBP segments, Bay zones, and the entire Bay using only those regions mapped for both years.

SAV increased 8% (1,854 ha, 4,580 ac) in the regions mapped for both years. This reverses most of the 2,328 hectare (5,749 ac) decline reported for 1998 in these same regions. The abundance of SAV in 1999 represented 58% of the portion of the Tier I goal (set by the Chesapeake Executive Council in Directive 93-3, 1993) adjusted to only include these mapped regions (44,610 ha, 110,187 ac).

SAV increased in one (Middle Bay) and decreased in two (Upper and Lower Bay) geographic zones delineated for Chesapeake Bay (see chart Figure 2b). In 1999, SAV increased in 25, decreased in 20, remained unvegetated in 26, and was not mapped in 7 of the 78 CBP segments (Table 6).

Upper Bay Zone

In the Upper Bay Zone (17 CBP segments extending south from the Susquehanna River to the Chester and Magothy rivers), 3,550 hectares (8,768 ac) of SAV were mapped for 1999. However, portions of the zone, including Spesutie Narrows and the Bush, Gunpowder, and Magothy rivers, representing 1,102 hectares (2,722 ac, 31% of the Zone total) of SAV in 1998, were not mapped for 1999. Comparing the same mapped regions between 1998 and 1999, SAV decreased 3% (88 ha, 218 ac) in 1999, comprising 57% of the adjusted Tier I goal (Table 7).

Two of the 17 segments increased by at least 20% and by at least 5 hectares from 1998 totals (see chart Figure 3; Table 6). These segments include:

	57%, Elk River (ELKOH), 323 ha (1999) vs. 206 ha (1998)
	42%, Sassafras River (SASOH), 97 ha (1999) vs. 69 ha (1998)

Five of the 17 segments (or mapped portions) decreased by at least 20% and by at least 5 hectares from 1998 totals (see chart Figure 3). These segments include:

	21%, Bohemia River (BOHOH), 37 ha (1999) vs. 46 ha (1998)
	100%, The mapped portion of Upper Chesapeake Bay (CB2OH), 0 ha (1999) vs. 33 ha (1998)
	63%, The mapped portion of Gunpowder River (GUNOH), 55 ha (1999) vs. 149 ha (1998)
	99%, The mapped portion of Upper Central Chesapeake Bay (CB3MH), 3 ha (1999) vs. 222 ha (1998)
	38%, Lower Chester River (CHSMH), 298 ha (1999) vs. 478 ha (1998)

Six of the 17 segments had no SAV or were not mapped (see chart Figure 3;Table 6).

Middle Bay Zone

In the Middle Bay Zone (33 CBP segments extending south from the Bay Bridge to the Rappahannock River and Pocomoke Sound, and including the Potomac River), 14,848 hectares (36,676 acres) of SAV were mapped for 1999. However, portions of the zone, including the upper Patuxent River and a small portion of the Severn River, representing 106 hectares (261 acres, 1% of the zone total) of SAV in 1998, were not mapped in 1999. Comparing the same mapped regions between 1998 and 1999, SAV increased 22% (2,717 ha, 6,711 acres) in 1999, comprising 59% of the adjusted Tier I goal for the Zone (Table 7).

Ten of the 33 segments increased by at least 20% and by at least 5 hectares from 1998 totals (see chart Figure 4;Table 6). These segments include:

	100%, Middle Central Chesapeake Bay (CB4MH), 10 ha (1999) vs. 0 ha (1998)
	81%, Eastern Bay (EASMH), 2,005 ha (1999) vs. 1,107 ha (1998)
	37%, Lower Central Chesapeake Bay (CB5MH), 906 ha (1999) vs. 661 ha (1998)
	144%, Honga River (HNGMH), 773 ha (1999) vs. 316 ha (1998)
	61%, Tangier Sound (TANMH), 4,299 ha (1999) vs. 2,676 ha (1998)
	591%, Manokin River (MANMH), 97 ha (1999) vs. 14 ha (1998)
	94%, Big Annemessex River (BIGMH), 183 ha (1999) vs. 94 ha (1998)
	38%, Lower Potomac River (POTMH), 951 ha (1999) vs. 692 ha (1998)
	22%, Upper Potomac River (POTTF), 1,327 ha (1999) vs. 1,089 ha (1998)
	29%, Mattawoman Creek (MATTF), 85 ha (1999) vs. 66 ha (1998)

Four of the 33 segments decreased by at least 20% and by at least 5 hectares from 1998 totals (see chart Figure 4). These segments include:

	33%, Mouth of the Choptank River (CHOMH1) 1,534 ha (1999) vs. 2,283 ha (1998)
	68%, South River (SOUMH), 7 ha (1999) vs. 22 ha (1998)
	25%, Middle Potomac River (POTOH), 1,316 ha (1999) vs. 1,743 ha (1998)
	60%, Piscataway Creek (PISTF), 51 ha (1999) vs. 127 ha (1998)

Fourteen of the 33 segments had no SAV or were not mapped (see chart Figure 4).

An alarming trend noted in previous years was reversed in the mid-section of Chesapeake Bay. SAV abundance in the Tangier Sound and Honga River segments increased by 2,080 ha (5,137 acres) after showing the largest single year decline in 1998 (1,724 ha, 4,258 acres). At the same time, the Choptank River Mouth Segment (CHOMH1) continues to decline from a peak abundance in 1997 (see chart Figure 4;Table 6).

Lower Bay Zone

In the Lower Bay Zone (28 CBP segments covering the region south from the Rappahannock River and Pocomoke Sound regions to the mouth of the Bay), 7,792 hectares (19,246 acres) were mapped for 1999. However, portions of the zone, including the upper York River, upper James River, and Chickahominy River, representing 345 hectares (853 acres, 4% of the zone total) of SAV in 1998, were not mapped in 1999. Comparing the same mapped regions between 1998 and 1999, SAV decreased 9% (775 ha, 1,913 acres) in 1999, comprising 57% of the adjusted Tier I goal for the Zone (Table 7).

Four of the 28 segments (or mapped portions) increased by at least 20% and by at least 5 hectares from 1998 totals (see chart Figure 5;Table 6). These segments include:

	277%, Lower Rappahannock River (RPPMH), 33 ha (1999) vs. 9 ha (1998)
	324%, Corrotoman River (CRRMH), 72 ha (1999) vs. 17 ha (1998)
	192%, The mapped portion of Chickahominy River (CHKOH), 37 ha (1999) vs. 13 ha (1998)
	126%, Lynnhaven & Broad Bays (LYNPH), 38 ha (1999) vs. 17 ha (1998)

One of the 28 segments decreased by at least 20% and by at least 5 hectares from 1998 totals (see chart Figure 5; Table 6). This segment was:

40%, Mouth of the James River (JMSPH), 31 ha (1999) vs. 52 ha (1998)

Fifteen segments had no SAV or were not mapped (see chart Figure 5; Table 6).

SAV declined in the Eastern Lower Chesapeake Bay (CB7PH) and Mobjack Bay (MOBPH) segments by 281 and 498 hectares (694 and 1,230 acres), respectively, representing a loss of 8% and 12% respectively, in each of these segments (see chart Figure 5; Table 6).

DELMARVA PENINSULA COASTAL BAYS ZONE

SAV beds in the Delmarva Peninsula Coastal Bays Zone (Assawoman, Isle of Wight, Sinepuxent, Chincoteague, and Southern Virginia Coastal Bays) continued to expand in area to 7,200 hectares (17,785 acres), the highest since the survey started in 1986, a 17% increase (1,046 ha, 2,583 acres) over 1998 (see chart Figure 6; Table 6).

	52%, Assawoman Bay (AAWPH), 265 ha (1999) vs. 175 ha (1998)
	23%, Isle of Wight Bay (IOWPH), 99 ha (1999) vs. 81 ha (1998)
	35%, Sinepuxent Bay (SPXPH), 643 ha (1999) vs. 478 ha (1998)
	14%, Chincoteague Bay (CHNPH), 6,193 ha (1999) vs. 5,421 ha (1998)

There continues to be no SAV mapped in the Southern Virginia Coastal Bays Segment; however, a small patch of SAV was reported by a ground survey in South Bay. Also, test transplantings from 1998 in Magothy Bay and South Bay continued to do well in 1999.