The Distribution of Submersed Aquatic 

Vegetation in the Fresh and Oligohaline Tidal 

Potomac River, 2005 

By Nancy B. Rybicki, Erika M. Justiniano- Vélez, Edward R. Schenk, Julie M. Baldizar and 

Sarah E. Hunter 

Potomac 

River 

Open-File Report 2008–1218

U.S. Department of the Interior 

U.S. Geological Survey 
ii

U.S. Department of the Interior 

Dirk Kempthorne, Secretary 

U.S. Geological Survey 

Mark Myers, Director 

U.S. Geological Survey, Reston, Virginia 2008 

For product and ordering information: 

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its natural and living resources, natural hazards, and the environment: 

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Suggested citation: 

Rybicki, N.B., Justiniano- Vélez, E., Schenk, E.R., and Hunter, S.E., 2008, The Distribution 

of Submersed Aquatic Vegetation in the Fresh and Oligohaline Tidal Potomac River, 2005. 

US Geological Survey, Reston VA, Open-File Report 2008-1218, 40 pgs. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report. 

Cover: Summer 2005 aerial photo of Dogue Creek and the Potomac River showing 

extensive dark areas of submersed aquatic vegetation. 

Photograph from Virginia Institute of Marine Science, 

http://www.vims.edu/bio/sav/2005_SAV_Photo_Gallery/pages/126-13_sept13-05.htm
iii

Contents 

Introduction.............................................................................................................. 1 

Methods .................................................................................................................. 2 

Results .................................................................................................................... 3 

Upper Tidal Potomac River (UTR).............................................................................. 3 

Lower Tidal Potomac River (LTR).............................................................................. 5 

Upper Oligohaline Potomac River Estuary (UOE) ......................................................... 6 

References Cited....................................................................................................... 7 

Figures 

1. Study area showing harvest sites and the three river segments, UTR, upper tidal river, 

LTR, lower tidal river, and UOE, upper oligohaline estuary of the Potomac River and 

the locations of the Aquatic Plant Management harvest sites in the tidal Potomac 

River .............................................................................................................. 8 

2. Percent cover of hydrilla in SAV beds located in the tidal Potomac River from 

Washington, DC to Dogue Creek, VA, 2005 ....................................................... 9 

3. Percent cover of hydrilla in SAV beds located in the tidal Potomac River from Dogue 

Creek, VA to Quantico Creek, VA, 2005 .......................................................... 10 

4. Percent cover of hydrilla in SAV beds located in the tidal Potomac River from 

Chopawamsic Creek, VA to the end of the river segment, 2005.......................... 11 

5. Location of each field bed in a continuous shoreline survey of Washington, DC, 

2005............................................................................................................ 12 

6. Location of each field bed in a continuous shoreline survey from Washington, DC to 

Broad Creek, MD, 2005.................................................................................. 13 

7. Location of each field bed in a continuous shoreline survey from Swan Creek, MD to 

Gunston Cove, VA, 2005 ............................................................................... 14 

8. Location of each field bed in a continuous shoreline survey from Mason Neck, VA to 

Quantico Creek, VA, 2005.............................................................................. 15 

9. Location of each field bed in a continuous shoreline survey near Quantico, VA, and 

Mallows Bay, MD 2005.................................................................................. 16 

10. Location of each field bed in a continuous shoreline survey from Wades Bay, MD to 

Potomac Creek, VA, 2005 .............................................................................. 17 
iv

11. Location of each field bed in a continuous shoreline survey from Aquia Creek, VA to 

the end of the river segment, 2005.................................................................. 18 

12. Distribution and density of submersed aquatic vegetation and the location of the 

Aquatic Plant Management harvest sites in the tidal Potomac River from Washington, 

DC to Broad Creek, MD, 2005......................................................................... 19 

13. Distribution and density of submersed aquatic vegetation and the location of the 

Aquatic Plant Management harvest sites in the tidal Potomac River from Broad 

Creek, MD to Chopawamsic Creek, VA, 2005................................................... 20 

14. Distribution and density of submersed aquatic vegetation and the location of the 

Aquatic Plant Management harvest sites in the tidal Potomac River from 

Chopawamsic Creek, VA to the downstream extent of the study, 2005............... 21 

15. Percent of available habitat (area less than 2m in depth) that was vegetated in each 

river segment (UTR, LTR, and UOE) from 1985 to 2005..................................... 22 

16. Area occupied by submersed aquatic vegetation for each river segment (UTR, LTR, and 

UOE) from 1985 to 2005................................................................................ 22 

Tables 

1. Percent canopy cover of each species and Shannon diversity index for field beds located 

in the tidal Potomac River, 2005...................................................................... 23 

Conversion Factors 

Multiply By To obtain 

Length 

inch (in.) 2.54 centimeter (cm) 

inch (in.) 25.4 millimeter (mm) 

foot (ft) 0.3048 meter (m) 

mile (mi) 1.609 kilometer (km) 

mile, nautical (nmi) 1.852 kilometer (km) 

yard (yd) 0.9144 meter (m) 

Area 

acre 4,047 square meter (m2) 

acre 0.4047 hectare (ha) 

acre 0.4047 square hectometer (hm2

) 

acre 0.004047 square kilometer (km2

) 

hectare 10000 square meter (m2

) 

hectare 0.01 square kilometer (km2

) 
square foot (ft2

) 929 square centimeter (cm2) 

square foot (ft2

) 0.0929 square meter (m2) 

square inch (in2

) 6.452 square centimeter (cm2) 

square mile (mi2

) 259 hectare (ha) 

square mile (mi2

) 2.59 square kilometer (km2) 

square meter (m2

) 0.000001 square kilometer (km2) 

v
The Distribution of Submersed Aquatic 

Vegetation in the Fresh and Oligohaline 

Tidal Potomac River, 2005 

By Nancy B. Rybicki, Erika M. Justiniano-Vélez, Edward R. Schenk, Julie M. 

Baldizar and Sarah E. Hunter 

Introduction 

Submersed aquatic vegetation (SAV) is a critical component of the Potomac 

River ecosystem (Fig. 1). Though SAV provides important habitat for fauna and 

stabilizes bottom sediment, very dense beds may restrict recreational and commercial 

navigation. Exotic species of SAV are managed by the Metropolitan Washington 

Council of Governments Potomac Aquatic Plant Management Program (PAPMP). 

Selected beds of primarily exotic SAV species that limit navigation are harvested 

mechanically. The program began in 1986 when approximately 40 acres of plants were 

harvested from 18 sites (Fig.1, Metropolitan Washington Council of Governments 1987). 

Monitoring efforts are an effective means of quantifying the distribution and 

abundance of the exotic species, Hydrilla verticillata (hydrilla) and other SAV species. 

These annual surveys provide a basis for identifying large-scale changes and trends 

throughout the ecosystem and allow managers to evaluate the effectiveness of resource 

management policies based on a reliable scientific foundation (Rybicki and Landwehr, 

2007). The U.S. Geological Survey (USGS) has monitored the distribution and 

composition of SAV beds in the fresh and oligohaline (salinity 0.5 to 5) tidal Potomac 

River since 1978 using transect sampling (1978 to 1981, 1985 to 1987, and 2002) and 

shoreline surveys (1983 to 2005). The Government of the District of Columbia has 

monitored the portion of the Potomac and Anacostia Rivers within Washington DC since 

1998 (Rottman, 1999; Ryan, 2005, 2006). 

The species of SAV observed in beds in the tidal Potomac River are incorporated 

into the Virginia Institute of Marine Science (VIMS) annual report on SAV distribution 

in Chesapeake Bay. The VIMS report and methods are available at 

http://www.vims.edu/bio/sav (Orth et al., 2006). Additional publications concerning 

SAV distribution in the Potomac River can be found at 

http://water.usgs.gov/nrp/proj.bib/sav/wethome.htm. 

 
Methods 

The study area in the Potomac River was divided into three reaches: 1) upper tidal 

river (UTR) from Washington, DC to Dogue Creek, VA; 2) lower tidal river (LTR) from 

Dogue Creek, VA to Quantico, VA; and 3) upper oligohaline estuary (UOE) from 

Quantico, VA to the downriver side of Maryland Point, MD (Figs. 1 to 5). 

 Observations of species composition in SAV beds were done by boat at 

approximately low tide (± 2 hrs) so that plants were visible from the water surface. 

Surveys were conducted between August and October 2005. We identified submersed 

plants to species level, recorded species composition of each bed, and estimated percent 

cover of each species within the bed. As in previous years, USGS monitored areas 

downriver of the Woodrow Wilson Bridge (Interstate 95) while colleagues at the 

Fisheries Division of the District of Columbia Department of Health (DCDOH) examined 

Washington DC waters in the tidal Anacostia and Potomac Rivers (Rottman 1999; Ryan 

2005). 

The monitoring effort in 2005 consisted of a continuous survey of all shoals and 

SAV beds within the study area (Fig. 1). SAV field beds are the isolated or contiguous 

SAV beds of different species composition sampled by boat. USGS personnel outlined 

SAV beds on 1:24,000 scale USGS quadrangle maps indicating location of all 

observations including unvegetated shoals (see Ruhl et al. 1998). DCDOH personnel 

used a global positioning system (GPS) to delineate the perimeter or length of beds and to 

record locations of each field bed. The SAV beds documented by the USGS and 

DCDOH were then entered into a geographic information system (GIS) to create maps of 

distribution and abundance. The percent of each species, the Shannon diversity index, 

and the bed density for each field bed are listed in Table 1. The Shannon diversity index 

for each field bed is calculated as: 

 M 

Diversity = -1 * Σ ((Pv/100) * ln (Pv/100)) 1 v=1 

where M represents richness (the total number of species observed) and Pv

represents the proportional coverage (from 0 to 100 percent) of each species. Diversity in 

each bed can range from 0.00 (if one species is present) to 2.49 (if all 12 species 

commonly found in the Potomac are present in equal percentages). Field bed 

observations, classified by the percent cover of Hydrilla verticillata, are shown in figures 

2 to 4. The species percent cover data shown in Table 1 correspond to field bed locations 

shown in figures 5 to 11

SAV beds shown in figures 12, 13, and 14 were delineated by VIMS 

(http://www.vims.edu/bio/sav/) based on aerial photographs acquired between August and 

October, then digitized and classified for ground cover density (from estimates of percent 

cover). The area and density of each photo-interpreted (PI) bed was determined by 

VIMS. Density was determined using the Crown Density Scale adapted from Paine 

(1981). Bed densities range from one to four with one corresponding to less than 10% 

vegetation coverage, two representing between 10 and 40% coverage, three representing 

between 41 and 70% coverage and four corresponding to 71 to 100% coverage. The 

2 
corresponding field data on species composition. Some beds were visible with air photos 

but not observed in the field if the area was not navigable due to water depth or obstacles. 

The VIMS SAV coverage data did not include beds below their detection limit. 

Therefore beds shown in figures 2 to 4 and figures 12 to 14 do not correspond exactly. 

The percent of each species in the three river segments (UTR, LTR, UOE) is 

summarized in the results section. The area of each species within a VIMS PI bed is 

computed based on a weighted-average formula. Using GIS software, we aligned each of 

the field beds with the PI beds to determine the area of each field bed and subsequently to 

calculate the coverage by species in each PI bed where species data were available. If 

more than one field observation was made in a PI bed, we sub-divided the PI bed area 

according to the relative size of each field bed and averaged species data proportionally 

(weighted average) to determine the percentage of each species in a PI bed and in the 

cumulative area of the study in each river reach (Rybicki and Landwehr, 2007). 

Results 

SAV coverage increased in all three river reaches between 2004 (Rybicki et al., 

2007) and 2005 (Figs. 15 and 16). In many beds hydrilla provided > 40% of the coverage 

(Figs. 2 to 4). The shoreline survey included 291 observations of field beds of various 

sizes (300 m2 to 400 km2) and density (Table 1). Most of the PAPMD harvest sites in the 

UTR, LTR, and UOE had 70 to 100 % cover (Figs. 12 to 14) and the beds were 

comprised of exotic species (Table 1; Figs. 2 to 4). Of the nine species observed in the 

Potomac River in 2005, three are exotic (hydrilla, Myriophyllum spicatum [milfoil], 

Najas minor [naiad]). Hydrilla dominated (> 40% of the coverage) all three river 

segments. Milfoil was abundant, but did not dominate any river segment. Naiad 

coverage comprised 13% and 9% of SAV coverage of the UTR and LTR, respectively, 

while only contributing to 3% of SAV coverage of the UOE. Two native species, 

Ceratophyllum demersum (coontail) and Vallisneria americana (wild celery) were 

abundant but did not dominate any river segment. Coontail coverage was similar in all 

three segments, ranging from 20% of the UTR to 19% of the LTR and 18% of the UOE. 

Wild celery comprised 4% of the UTR, 15% of the LTR, and 7% of the UOE SAV 

coverage. No Elodea canadensis (waterweed) was observed, but Stuckenia pectinata 

(sago pondweed) was present. Some species were relatively rare, namely the macroalga 

Chara vulgaris (muskgrass), Najas guadalupensis (southern naiad), and Heteranthera 

dubia (stargrass). 

The mean daily river flow for 2005 was 344 m3

s

-1 and was considered normal, 

while the last two years were considered high flow. The 25 (low), 50 (median), and 75 

(high) percentile of the mean daily flow is 243, 301 and 398 m3

s

-1, respectively, at the 

Washington DC gage (station 01646500) for the period of record 

(http://waterdata.usgs.gov/nwis/sw). The return to normal flow in 2005 may help explain 

why the SAV increased between 2004 and 2005 in all river segments (Fig 16). 

Upper Tidal Potomac River (UTR) 

In the UTR, we found the following nine SAV species, in order from most to least 

abundant: 44% hydrilla, 20% coontail, 17% milfoil, 13% naiad, 4% wild celery, 1% 

3 
southern naiad, and traces of muskgrass, water stargrass, and sago pondweed. Compared 

to 2004, coontail, milfoil, and naiad coverage increased in 2005, while hydrilla and wild 

celery coverage decreased considerably. 

No SAV was observed in the Anacostia River (Fig. 5), yet a few beds were 

present there in the past. Bed #267, which is in the Washington Channel, has been 

perennial for many years. That bed decreased in density between 2004 and 2005. 

In Washington DC, in the Potomac River, SAV coverage increased substantially 

from 2004 to 2005. While hydrilla and wild celery alternated in dominance among beds 

in 2004, hydrilla dominated most beds in 2005. However, coontail coverage increased 

substantially in 2005 and naiad, which was not present last year, spread throughout much 

of the region. Hydrilla coverage was 100% in some DC beds (Table 1). 

The Woodrow Wilson Bridge has been under re-construction since 2001 and is 

expected to be completed by 2010. Dredging, to allow for a barge channel below the 

bridge and between the bridge and the nearby Maryland shore, was conducted between 

November and February 2001 (http://www.wilsonbridge.com). The dredging caused the 

destruction of ~34 acres (14 ha) of SAV on the shoals near the Woodrow Wilson Bridge. 

Seagrass transplantation was conducted in the lower Potomac River as part of a 

compensatory mitigation to account for the SAV loss (Schenk and Rybicki, 2006). In 

2002, except in the dredge path, the SAV on the shoals near the Woodrow Wilson Bridge 

was dense and extensive (http://www.vims.edu/bio/sav) (Orth et al., 2006). In 2003, 

however, precipitation and river flow were well above average and SAV on these shoals, 

and elsewhere in Washington DC waters, declined dramatically. The high sediment load 

and high flows apparently buried or scoured SAV away, or the cloudy conditions and 

muddy waters reduced available light reaching the bottom and diminished SAV 

productivity. 

 In 2005, SAV was abundant near the Woodrow Wilson Bridge for the first time 

since 2003. Large, dense beds were present at the mouth of Huntington Creek and in the 

middle of the Potomac River, just upstream of the Woodrow Wilson Bridge (Figs. 6 and 

12). Naiad codominated (with hydrilla) in one bed in Huntington Creek and was also 

found in the Woodrow Wilson Bridge bed (Fig 2; Table 1). Vegetation along the 

Virginia side of the Potomac River downstream of Huntington Creek was intermittent 

and consisted mostly of dense hydrilla beds, but naiad was also found in many of these 

beds. Only trace amounts of milfoil were found in this area (Figs. 2, 3, 12, and 13). 

Beds shown in figures 2 (field beds) and 12 (PI beds) do not exactly correspond. 

Above the Woodrow Wilson Bridge, some beds were only detected in the field. Below 

the bridge, some beds were only detected in photos. 

Many of the beds on the mainstem of the Potomac were dominated by hydrilla but 

well mixed with other species too (Fig. 3; Table1). In Piscataway Creek (Maryland), 

hydrilla existed with naiad and coontail while trace amounts of milfoil were found. Beds 

in Piscataway Creek and Dogue Creek, that were previously dominated by hydrilla, are 

either dominated by hydrilla or are mixed beds with milfoil, coontail, and hydrilla (Figs. 

3 and 7; Table1). Milfoil dominated the beds upstream of Little Huntington Creek 

(Virginia) and beds along the shoreline south to the lower extent of the UTR (Figs. 3 and 

7; Table1). Between 2004 and 2005, there was an increase in coontail, hydrilla, and 

milfoil along the Maryland shore from Piscataway Creek to the lower extent of the UTR 

(Figs. 3 and 7; Table1). 

4 
The shore just upstream from Little Huntington Creek supported the only traces of 

chara in the entire study area (Figs. 3 and 7; Table1). Southern naiad was found in many 

of the beds, including the mouths of Swan Creek, Piscataway Creek, and Dogue Creek 

(Figs. 3 and 7; Table1). Southern naiad was also found in beds between Little 

Huntington Creek and Dogue Creek on the Virginia shoreline. It was also present south 

of Piscataway Creek near the lower reaches of the UTR along the Maryland shoreline. 

The lower reaches of the UTR had supported the only population of sago pondweed in 

the study area in 2004 and 2005 (Fig. 7; Table1). 

 

Lower Tidal Potomac River (LTR) 

In the LTR we found seven SAV species. The SAV coverage was 45% hydrilla, 

19% coontail, 15% wild celery, 10% milfoil, 9% naiad, 1% southern naiad, and < 1% 

water stargrass. Between 2004 and 2005, the percent of hydrilla, milfoil, and wild celery 

decreased and coontail increased substantially. Hydrilla was the dominant species and 

naiad spread throughout much of the LTR, where very little of it was found in 2004 (Fig. 

3). In contrast to 2004, stargrass was present and muskgrass was absent in 2005. 

Hydrilla was the dominant species in the upstream beds of Gunston Cove, similar 

to 2004, but along the northern shore of Gunston Cove, a mix of milfoil, hydrilla, and 

coontail was observed where wild celery dominated last year (Figs. 3 and 7; Table 1). In 

contrast to 2004, wild celery has shifted from the northern mouth of Gunston Cove to the 

upstream beds; however, naiad has spread throughout most of the cove where it was not 

present in 2004. Small populations of southern naiad were found in the narrow fringing 

downstream beds of the cove, along with milfoil, coontail, wild celery, and hydrilla, 

which either codominated or altered in dominance (Figs. 3 and 7; Table 1). Across from 

Gunston Cove and south to Pomonkey Creek, on the Maryland side of the Potomac 

River, hydrilla dominated in 2005, though wild celery was the dominant species in 2004 

(Figs. 3 and 8; Table 1). 

Wild celery was the dominant species around Mason Neck, which was observed 

in 2004, but hydrilla was the dominant species in Pomonkey Creek, where wild celery 

dominated in 2004. New in 2005 was the presence of water stargrass in Pomonkey 

Creek. SAV was sparse at Indian Head between Pomonkey Creek and downstream to 

Mattawoman Creek, and consisted mainly of beds that were dominated by milfoil, which 

was also observed in 2004 (Figs. 3 and 8; Table 1). 

SAV coverage in the Mattawoman Creek increased substantially from 2004. 

Coontail, wild celery, and hydrilla were abundant in the mouth of the Mattawoman. 

Milfoil was one of the dominant species in 2004, but that was not observed in 2005, 

though milfoil coverage spread throughout more of the creek. Hydrilla was the dominant 

species in the upstream portions of the Mattawoman Creek, but there were occasional 

beds dominated by coontail. Naiad spread throughout much of the creek in 2005, when 

very little was present in 2004. Trace amounts of southern naiad were also found in this 

creek, which were not present in 2004 (Figs. 3 and 8; Table 1). 

Chicamuxen Creek was densely vegetated in 2005, with milfoil observed as the 

dominant species, as was seen in 2004. Chicamuxen Creek is traditionally one of the 

more diverse beds in the study area, and in 2005 two relatively rare SAV species were 

found, water stargrass and southern naiad; chara, present in 2004, was not observed. At 

5 
the mouth of the Chicamuxen Creek, a bed was dominated by southern naiad (Figs. 3, 8, 

and 9; Table 1). 

Hydrilla was more abundant in Belmont Bay in 2004 and 2005 than in previous 

years. Upstream in the Occoquan River, hydrilla, wild celery, and naiad occurred in beds 

where hydrilla, with a trace of southern naiad, was the dominant species in 2004 (Figs. 3 

and 8; Table 1). Neabsco Creek and Powells Creek were both dominated by hydrilla in 

2005, with some coontail mixed in. Hydrilla was the dominant species along the shore 

north of Quantico Creek on the Virginia side of the Potomac River. Hydrilla also 

dominated the upstream beds in the mouth of Quantico Creek and along the upstream 

side of the creek. Coontail dominated the downstream side of Quantico Creek along with 

the beds in the downstream mouth of the creek. There was one dominant wild celery bed 

in the middle of Quantico Creek (Figs. 3, 8, and 9; Table 1). 

Upper Oligohaline Potomac River Estuary (UOE) 

Eight SAV species were present in 2005 in this study area with the following 

composition: 42.5% hydrilla, 26% milfoil, 18% coontail, 7% wild celery, 3% naiad, 2% 

sago pondweed, 1% southern naiad and < 1% stargrass. In 2005, the percentage of 

milfoil decreased substantially while wild celery, coontail, hydrilla, sago pondweed, and 

naiad coverage increased compared to previous years. In contrast to 2004, southern naiad 

and sago pondweed were present in 2005 and waterweed was absent. Hydrilla was the 

dominant species in many locations along the Virginia side of the Potomac River and 

milfoil and wild celery were the dominant species along the Maryland side in 2005. 

However SAV coverage on the Maryland side of the Potomac River was less than 

coverage on the Virginia side. 

Hydrilla and wild celery alternated in dominance along the Maryland side of the 

Potomac River north of Mallows Bay, where milfoil was the dominant species in 2004 

(Figs. 4 and 9; Table 1). SAV in Mallows Bay consisted primarily of hydrilla, but naiad 

and coontail were also present. Milfoil was the most abundant species in the bay north of 

Wades Bay (Figs. 4 and 9; Table 1). In Wades Bay wild celery was the dominant 

species, though small populations of coontail and hydrilla were also present. Wades Bay 

supported the only populations of sago pondweed and southern naiad on the Maryland 

side of the Potomac River in the UOE, where one large bed of each was located (Figs. 4 

and 10; Table 1). 

Coontail was the most abundant species in the cove south of Quantico, VA and 

north of the Chopawamsic Creek. The mouth of the Chopawamsic Creek consisted 

primarily of coontail, while the inner beds consisted mostly of hydrilla with some milfoil 

(Figs. 4 and 9; Table 1). The region south of Quantico, along with shoreline beds south 

of Chopawamsic Creek, supported the only populations of naiad in 2004 but in 2005, 

naiad was not found in these beds. SAV coverage decreased along the Virginia shoreline 

between Chopawamsic Creek and Aquia Creek from 2004 to 2005 (Figs. 4, 9, and 10; 

Table 1). The beds that were present consisted mostly of milfoil, but wild celery, 

hydrilla, and coontail were also observed there as well (Figs. 4, 9, and 10; Table 1). 

On the north shoreline at the mouth of Aquia Creek, two beds contained large 

populations of sago pondweed (Figs. 4 and 10; Table 1). The rest of the beds were 

dominated primarily by coontail, along with some smaller populations of the other 

6 
common SAV species and southern naiad. The upstream beds of Aquia Creek and the 

south shore were dominated by hydrilla (Figs. 4 and 10; Table 1). The south shoreline at 

the mouth of Aquia Creek along with the cove just below it were dominated by milfoil, as 

were the beds located along the shore south to the mouth of Potomac Creek. Within 

Potomac Creek, near the mouth, beds of hydrilla, milfoil, wild celery, and naiad were 

found (Figs. 4 and 10; Table 1). SAV was not found in the upper reaches of the Potomac 

Creek, where hydrilla was the only species found in 2004. A bed just south of Potomac 

Creek supported the only population of water stargrass in this portion of the study area 

(Figs. 4 and 10; Table 1). 

References Cited 

Metropolitan Washington Council of Governments. 1987. Potomac SAV news, no. 2 

Summer 1987. 

Orth, R. J., Wilcox, D. J., Nagey, L. S., Owens, A. L., Whiting, J. R., and Kenne, A. K. 

2006. 2005 Distribution of Submerged Aquatic Vegetation in the Chesapeake Bay and 

Coastal Bays. VIMS Special Scientific Report Number 147. Final report to U.S. EPA, 

Chesapeake Bay Program, Annapolis, MD. Grant No. CB973219-01-0, 

http://www.vims.edu/bio/sav/sav05/index.html 

Paine, D.P. 1981. Aerial Photography and Image Interpretation for Resource 

Management. John Wiley and Sons, Inc., New York City, NY. 571 pp. 

Rottman, A. 1999. Aquatic Vegetation Monitoring 1998. Submitted to U.S. Fish and 

Wildlife Service for the Fisheries and Wildlife Division of the Government of the 

District of Columbia. Report F-2-8-13. 

Ruhl, H.A., Rybicki, N.B., Reel, J.T., and Carter, V. 1999. Distribution and Abundance 

of Submersed Aquatic Vegetation in the Tidal Potomac River and Upper Potomac 

Estuary, Maryland, Virginia, and the District of Columbia, 1993-1998 (U. S. 

Geological Survey Open-File Report 99-233). 

Ryan, D. 2005. 2004 Submerged Aquatic Vegetation Survey of the Potomac and 

Anacostia Rivers within the District of Columbia. Submitted to U.S. Fish and Wildlife 

Service for the Fisheries and Wildlife Division of the Government of the District of 

Columbia. Report F-2-R-19. 

Ryan, D. 2006. 2005 Submerged Aquatic Vegetation Survey of the Potomac and 

Anacostia Rivers within the District of Columbia. Submitted to U.S. Fish and Wildlife 

Service for the Fisheries and Wildlife Division of the Government of the District of 

Columbia. Report F-2-R-20. 

Rybicki, N.B., and Landwehr, J.M. 2007. Long-term Changes in Abundance and 

Diversity of Macrophyte and Waterfowl Populations in an Estuary with Exotic 

Macrophytes and Improving Water Quality, Limnology and Oceanography, 52(3): p. 

1195-1207. 

Rybicki, N.B., Yoon, S.N., Schenk, E.R., and Baldizar, J.B., 2007, The Distribution of 

Submersed Aquatic Vegetation in the Fresh and Oligohaline Tidal Potomac River, 

2004 , U.S. Geological Survey Open-File Report 2007-1198 

Schenk, E. R. and Rybicki, N. B., 2006, Exploring causes of a seagrass transplant failure 

in the Potomac River (Virginia), Ecological Restoration, v. 24, no. 2, p. 116-118. 

7 
Figure 1. Study area showing the three river segments, UTR, upper tidal 

river, LTR, lower tidal river, and UOE, upper oligohaline estuary of the 

Potomac River and the locations of the Aquatic Plant Management harvest 

sites in the tidal Potomac River.

8 
 9 

Figure 2. Percent cover of hydrilla in SAV beds located in the tidal Potomac 

River from Washington, DC to Dogue Creek, MD, 2005. UTR is the Upper 

and LTR is the Lower Tidal river study segment. 
10 

Figure 3. Percent cover of hydrilla in SAV beds located in the tidal Potomac River from Dogue C

Quantico Creek, VA, 2005. UTR is the Upper and LTR is the Lower Tidal River study segment.
11 

Figure 4. Percent cover of hydrilla in SAV beds located in the tidal Potomac River from Chopawa

the end of the river segment, 2005. UOE is the Upper Oligohaline Estuary study segment.
Figure 5. Location of each field bed in a continuous shoreline survey of Washington, DC, 2005. 

Tidal River study segment. 

12 
Figure 6. Location of each field bed in a continuous shoreline survey from Washington, DC to Bro

2005. 

13 
Figure 7. Location of each field bed in a continuous shoreline survey from Swan Creek, MD to G

2005. River segments are the Upper Tidal River (UTR) and Lower Tidal River (LTR).

14 
Figure 8. Location of each field bed in a continuous shoreline survey from Mason Neck, VA to Qu

2005.

15 
Figure 9. Location of each field bed in a continuous shoreline survey near Quantico, VA and Ma

2005. River segments are the Lower Tidal River (LTR) and Upper Oligohaline Estuary (UOE). 

16 
Figure 10. Location of each field bed in a continuous shoreline survey from Wades Bay, MD to Po

2005.

17 
Figure 11. Location of each field bed in a continuous shoreline survey from Aquia Creek, VA to 

segment, 2005. UOE is the Upper Oligohaline Estuary river segment.

18 
Figure 12. Distribution and density of submersed aquatic vegetation and the locations of the Aqu

Management harvest sites in the tidal Potomac River from Washington, DC to Broad Creek, MD, Upper Tidal River study segment.

19 
Figure 13. Distribution and density of submersed aquatic vegetation and the locations of the Aqu

Management harvest sites in the tidal Potomac River from Broad Creek, MD to Chopawamsic Cre

The river segments are the Upper Tidal River (UTR), Lower Tidal River (LTR), and the Upper Oligo(UOE).

20 
Figure 14. Distribution and density of submersed aquatic vegetation and the locations of the Aqu

Management harvest sites in the tidal Potomac River from Chopawamsic Creek, VA to the downs

the study, 2005. UOE is the Upper Oligohaline Estuary study segment. 

21 
22 

0

19851986198719881989199019911992199319941995

10

20

30

40

50

60

199619971998

Year

Pecent of available habitat with SAV

1999200020012002200320042005

UTR LTR UOE

Figure 15. Percent of available habitat (area less than 2m in depth) that was 

vegetated in each river segment (UTR, LTR, and UOE) from 1985 to 2005. 

The UTR, LTR, and UOE have 2956, 5173, and 3,355 hectares of available 

habitat, respectively. 

0

200

400

600

800

1000

1200

1400

1600

1800

198519861987198819891990199119921993199419951996199719981999200020012002200320042005

Year

SAV area (ha)

UTR LTR UOE

Figure 16. Area occupied by submersed aquatic vegetation (SAV) for each 

river segment (UTR, LTR, and UOE) from 1985 to 2005. SAV area from 

Virginia Institute of Marine Science 

(http://www.vims.edu/bio/sav/historical.html) except from US Geological 

Survey in 1988 (Rybicki and Landwehr, 2007). 
Table 1. Percent canopy cover of each species and Shannon diversity index for field beds located 

along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond to the numb

11. Density classes are USGS field data based on a Braun-Blanquet crown cover model where: 1 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each species in abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologic

is DC Dept. of Health. Div is Shannon diversity index.

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

11/4/2005 1 USGS Indian Head 4 40.0 5.0 10.0 30.0 15.0 0.0 0.0 11/4/2005 2 USGS Indian Head 4 20.0 5.0 0.0 40.0 15.0 20.0 0.0 

11/4/2005 3 USGS Indian Head 4 30.0 5.0 0.0 30.0 15.0 20.0 0.0 

11/4/2005 4 USGS Indian Head 4 40.0 5.0 20.0 20.0 15.0 0.0 0.0 

11/4/2005 5 USGS Indian Head 4 20.0 25.0 0.0 30.0 15.0 10.0 0.0 11/4/2005 6 USGS Indian Head 4 5.0 5.0 85.0 5.0 0.0 0.0 0.0 

11/4/2005 7 USGS Indian Head 4 70.0 5.0 0.0 20.0 5.0 0.0 0.0 

11/4/2005 8 USGS Indian Head 3 35.0 10.0 20.0 35.0 0.0 0.0 0.0 

11/4/2004 9 USGS Indian Head 4 74.0 1.0 10.0 15.0 0.0 0.0 0.0 

11/4/2005 10 USGS Indian Head 4 47.0 5.0 0.0 46.0 2.0 0.0 0.0 

11/4/2005 11 USGS Indian Head 3 95.0 5.0 0.0 0.0 0.0 0.0 0.0 11/4/2005 12 USGS Indian Head 4 60.0 0.0 0.0 35.0 5.0 0.0 0.0 11/4/2005 13 USGS Indian Head 3 100.0 0.0 0.0 0.0 0.0 0.0 0.0 

11/4/2005 14 USGS Indian Head 4 100.0 0.0 0.0 0.0 0.0 0.0 0.0 

11/4/2005 15 USGS Indian Head 2 70.0 0.0 30.0 0.0 0.0 0.0 0.0 

11/4/2005 16 USGS Indian Head 3 45.0 15.0 15.0 15.0 10.0 0.0 0.0 

11/4/2005 17 USGS Indian Head 2 85.0 15.0 0.0 0.0 0.0 0.0 0.0 

11/4/2005 18 USGS Indian Head 4 30.0 10.0 0.0 40.0 20.0 0.0 0.0 11/4/2005 19 USGS Indian Head 4 45.0 10.0 5.0 35.0 5.0 0.0 0.0 

11/4/2005 20 USGS Indian Head 2 5.0 5.0 85.0 0.0 5.0 0.0 0.0 11/4/2005 21 USGS Indian Head 3 35.0 15.0 35.0 15.0 0.0 0.0 0.0 11/4/2005 22 USGS Indian Head 4 40.0 10.0 0.0 45.0 5.0 0.0 0.0 11/4/2005 23 USGS Indian Head 4 0.0 30.0 70.0 0.0 0.0 0.0 0.0 

23 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass),P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologica

is DC Dept. of Health. Div is Shannon diversity index. 

Survey 

 date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

11/4/2005 24 USGS Indian Head 4 30.0 35.0 0.0 35.0 0.0 0.0 0.0 11/4/2005 25 USGS Indian Head 4 65.0 20.0 0.0 15.0 0.0 0.0 0.0 

11/2/2005 26 USGS Quantico 3 0.0 30.0 20.0 50.0 0.0 0.0 0.0 

11/2/2005 27 USGS Quantico 4 15.0 25.0 0.0 60.0 0.0 0.0 0.0 

11/2/2005 28 USGS Quantico 3 15.0 10.0 0.0 75.0 0.0 0.0 0.0 

11/2/2005 29 USGS Quantico 3 40.0 40.0 0.0 20.0 0.0 0.0 0.0 

11/2/2005 30 USGS Quantico 2 30.0 60.0 0.0 10.0 0.0 0.0 0.0 

11/2/2005 31 USGS Quantico 3 25.0 50.0 0.0 25.0 0.0 0.0 0.0 

11/2/2005 32 USGS Quantico 4 30.0 0.0 0.0 70.0 0.0 0.0 0.0 

11/2/2005 33 USGS Quantico 4 70.0 15.0 0.0 15.0 0.0 0.0 0.0 

11/2/2005 34 USGS Widewater 3 20.0 60.0 0.0 20.0 0.0 0.0 0.0 

11/2/2005 35 USGS Widewater 4 90.0 0.0 0.0 10.0 0.0 0.0 0.0 

11/2/2005 36 USGS Widewater 4 24.0 71.0 5.0 0.0 0.0 0.0 0.0 

11/2/2005 37 USGS Widewater 3 70.0 30.0 0.0 0.0 0.0 0.0 0.0 

11/2/2005 38 USGS Widewater 4 10.0 45.0 0.0 45.0 0.0 0.0 0.0 

11/2/2005 39 USGS Widewater 3 0.0 60.0 40.0 0.0 0.0 0.0 0.0 

11/2/2005 40 USGS Widewater 4 5.0 40.0 17.0 35.0 3.0 0.0 0.0 

11/2/2005 41 USGS Widewater 4 5.0 35.0 15.0 15.0 0.0 0.0 0.0 

11/2/2005 42 USGS Widewater 4 20.0 20.0 10.0 10.0 0.0 0.0 0.0 

11/2/2005 43 USGS Widewater 4 60.0 25.0 5.0 10.0 0.0 0.0 0.0 

11/2/2005 44 USGS Widewater 4 10.0 15.0 10.0 65.0 0.0 0.0 0.0 

11/2/2005 45 USGS Widewater 4 0.0 0.0 60.0 40.0 0.0 0.0 0.0 

24 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index.

Survey 

 date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

11/2/2005 46 USGS Widewater 4 10.0 5.0 0.0 65.0 20.0 0.0 0.0 11/2/2005 47 USGS Widewater 4 5.0 15.0 0.0 65.0 0.0 15.0 0.0 

11/2/2005 48 USGS Widewater 4 35.0 15.0 0.0 50.0 0.0 0.0 0.0 

11/2/2005 49 USGS Widewater 4 40.0 15.0 1.0 1.0 35.0 8.0 0.0 

11/2/2005 50 USGS Widewater 2 0.0 100.0 0.0 0.0 0.0 0.0 0.0 

11/2/2005 51 USGS Widewater 4 50.0 15.0 0.0 30.0 5.0 0.0 0.0 

11/2/2005 52 USGS Widewater 4 60.0 10.0 0.0 0.0 0.0 30.0 0.0 

11/2/2005 53 USGS Widewater 4 90.0 10.0 0.0 0.0 0.0 0.0 0.0 

11/2/2005 54 USGS Widewater 4 100.0 0.0 0.0 0.0 0.0 0.0 0.0 

10/28/2005 55 USGS Mount Vernon 4 25.0 20.0 30.0 25.0 0.0 0.0 0.0 

10/28/2005 56 USGS Fort Belvoir 4 25.0 20.0 30.0 25.0 0.0 0.0 0.0 

10/28/2005 57 USGS Fort Belvoir 4 24.0 1.0 70.0 0.0 0.0 0.0 0.0 

10/28/2005 58 USGS Fort Belvoir 4 20.0 0.0 80.0 0.0 0.0 0.0 0.0 

10/28/2005 59 USGS Fort Belvoir 4 45.0 5.0 50.0 0.0 0.0 0.0 0.0 

10/28/2005 60 USGS Fort Belvoir 4 85.0 0.0 15.0 0.0 0.0 0.0 0.0 

10/28/2005 61 USGS Fort Belvoir 4 85.0 0.0 10.0 5.0 0.0 0.0 0.0 

10/28/2005 62 USGS Fort Belvoir 3 60.0 0.0 35.0 5.0 0.0 0.0 0.0 

10/28/2005 63 USGS Fort Belvoir 4 30.0 2.0 0.0 38.0 30.0 0.0 0.0 

10/28/2005 64 USGS Fort Belvoir 4 60.0 0.0 25.0 0.0 15.0 0.0 0.0 

10/28/2005 65 USGS Fort Belvoir 4 70.0 5.0 10.0 10.0 5.0 0.0 0.0 

10/28/2005 66 USGS Fort Belvoir 4 48.0 10.0 2.0 40.0 0.0 0.0 0.0 

25 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index. 

Survey 

 date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

10/28/2005 67 USGS Fort Belvoir 4 71.0 2.0 2.0 20.0 5.0 0.0 0.0 10/28/2005 68 USGS Fort Belvoir 4 55.0 1.0 0.0 44.0 0.0 0.0 0.0 

10/28/2005 69 USGS Fort Belvoir 4 69.0 1.0 0.0 30.0 0.0 0.0 0.0 

10/28/2005 70 USGS Fort Belvoir 4 45.0 5.0 0.0 30.0 20.0 0.0 0.0 

10/28/2005 71 USGS Fort Belvoir 4 60.0 3.0 0.0 20.0 15.0 2.0 0.0 

10/28/2005 72 USGS Fort Belvoir 3 50.0 0.0 0.0 50.0 0.0 0.0 0.0 

10/28/2005 73 USGS Fort Belvoir 1 50.0 0.0 0.0 50.0 0.0 0.0 0.0 

10/28/2005 74 USGS Fort Belvoir 4 30.0 30.0 10.0 30.0 0.0 0.0 0.0 10/28/2005 75 USGS Fort Belvoir 3 0.0 40.0 0.0 60.0 0.0 0.0 0.0 

10/28/2005 76 USGS Fort Belvoir 4 30.0 15.0 10.0 20.0 15.0 10.0 0.0 

10/28/2005 77 USGS Fort Belvoir 4 0.0 15.0 80.0 5.0 0.0 0.0 0.0 

10/28/2005 78 USGS Fort Belvoir 4 20.0 10.0 70.0 0.0 0.0 0.0 0.0 

10/28/2005 79 USGS Fort Belvoir 4 30.0 2.0 40.0 28.0 0.0 0.0 0.0 

10/28/2005 80 USGS Fort Belvoir 4 25.0 0.0 60.0 15.0 0.0 0.0 0.0 

10/28/2005 81 USGS Fort Belvoir 3 30.0 15.0 55.0 0.0 0.0 0.0 0.0 

10/28/2005 82 USGS Fort Belvoir 4 0.0 5.0 95.0 0.0 0.0 0.0 0.0 

10/28/2005 83 USGS Fort Belvoir 3 5.0 30.0 45.0 15.0 5.0 0.0 0.0 

10/28/2005 84 USGS Fort Belvoir 3 10.0 10.0 80.0 0.0 0.0 0.0 0.0 

10/26/2005 85 USGS Mount Vernon 3 10.0 20.0 65.0 5.0 0.0 0.0 0.0 

10/26/2005 86 USGS Mount Vernon 4 69.5 20.0 0.0 10.0 0.5 0.0 0.0 

10/26/2005 87 USGS Mount Vernon 4 60.0 5.0 0.0 35.0 0.0 0.0 0.0 10/26/2005 88 USGS Mount Vernon 4 69.0 5.0 1.0 10.0 10.0 5.0 0.0 

10/26/2005 89 USGS Mount Vernon 2 20.0 40.0 20.0 20.0 0.0 0.0 0.0 

26 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index. 

Survey 

 date 

Field 

bed 

number

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD P_

10/26/2005 90 USGS Mount Vernon 3 30.0 20.0 20.0 10.0 10.0 10.0 0.0 0.0 10/26/2005 91 USGS Mount Vernon 4 30.0 30.0 0.0 40.0 0.0 0.0 0.0 0.0 

10/26/2005 92 USGS Mount Vernon 4 80.0 0.0 0.0 10.0 10.0 0.0 0.0 0.0 

10/26/2005 93 USGS Mount Vernon 3 50.0 25.0 0.0 10.0 10.0 5.0 0.0 0.0 

10/26/2005 94 USGS Mount Vernon 2 20.0 40.0 40.0 0.0 0.0 0.0 0.0 0.0 

10/26/2005 95 USGS Mount Vernon 4 40.0 20.0 10.0 15.0 0.0 15.0 0.0 0.0 

10/26/2005 96 USGS Mount Vernon 4 38.0 30.0 0.0 30.0 0.0 1.0 0.0 0.0 

10/26/2005 97 USGS Mount Vernon 2 0.0 80.0 0.0 20.0 0.0 0.0 0.0 0.0 

10/26/2005 98 USGS Mount Vernon 1 0.0 80.0 0.0 20.0 0.0 0.0 0.0 0.0 

10/26/2005 99 USGS Mount Vernon 4 20.0 60.0 0.0 20.0 0.0 0.0 0.0 0.0 

10/26/2005 100 USGS Mount Vernon 3 70.0 0.0 0.0 30.0 0.0 0.0 0.0 0.0 

10/26/2005 101 USGS Alexandria 3 70.0 0.0 0.0 30.0 0.0 0.0 0.0 0.0 

10/26/2005 102 USGS Fort Belvoir 4 69.0 5.0 1.0 10.0 10.0 5.0 0.0 0.0 

10/14/2005 103 USGS Mount Vernon 3 29.0 1.0 0.0 20.0 50.0 0.0 0.0 0.0 

10/14/2005 104 USGS Mount Vernon 2 0.0 20.0 80.0 0.0 0.0 0.0 0.0 0.0 

10/14/2005 105 USGS Mount Vernon 3 20.0 20.0 5.0 40.0 15.0 0.0 0.0 0.0 

10/14/2005 106 USGS Mount Vernon 4 35.0 10.0 0.0 35.0 20.0 0.0 0.0 0.0 

10/14/2005 107 USGS Mount Vernon 3 18.0 40.0 1.0 40.0 0.0 1.0 0.0 0.0 

10/14/2005 108 USGS Mount Vernon 4 40.0 30.0 0.0 30.0 0.0 0.0 0.0 0.0 

10/14/2005 109 USGS Mount Vernon 4 70.0 0.0 0.0 0.0 30.0 0.0 0.0 0.0 

10/14/2005 110 USGS Mount Vernon 4 80.0 16.0 0.0 2.0 2.0 0.0 0.0 0.0 

10/14/2005 111 USGS Mount Vernon 3 40.0 10.0 0.0 20.0 30.0 0.0 0.0 0.0 

27 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each sabbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologic

is DC Dept. of Health. Div is Shannon diversity index. 

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

10/14/2005 112 USGS Mount Vernon 2 70.0 12.0 3.0 10.0 0.0 5.0 0.0 10/14/2005 113 USGS Mount Vernon 2 20.0 10.0 10.0 20.0 40.0 0.0 0.0 

10/14/2005 114 USGS Mount Vernon 4 25.0 15.0 0.0 35.0 25.0 0.0 0.0 

10/14/2005 115 USGS Mount Vernon 2 60.0 10.0 0.0 0.0 30.0 0.0 0.0 

10/14/2005 116 USGS Mount Vernon 2 50.0 0.0 20.0 20.0 0.0 10.0 0.0 

10/14/2005 117 USGS Mount Vernon 4 80.0 0.0 0.0 20.0 0.0 0.0 0.0 

10/14/2005 118 USGS Mount Vernon 2 50.0 50.0 0.0 0.0 0.0 0.0 0.0 

10/14/2005 119 USGS Mount Vernon 4 40.0 40.0 0.5 10.0 9.5 0.0 0.0 

10/14/2005 120 USGS Mount Vernon 4 40.0 10.0 20.0 10.0 20.0 0.0 0.0 

10/14/2005 121 USGS Mount Vernon 4 100.0 0.0 0.0 0.0 0.0 0.0 0.0 

10/14/2005 122 USGS Mount Vernon 3 30.0 0.0 30.0 20.0 20.0 0.0 0.0 

10/14/2005 123 USGS Mount Vernon 4 60.0 0.0 0.0 30.0 10.0 0.0 0.0 

10/14/2005 124 USGS Mount Vernon 4 32.0 2.0 0.0 34.0 32.0 0.0 0.0 10/14/2005 125 USGS Mount Vernon 4 85.0 1.0 0.0 10.0 4.0 0.0 0.0 

10/14/2005 126 USGS Alexandria 4 32.0 2.0 0.0 34.0 32.0 0.0 0.0 

10/14/2005 127 USGS Alexandria 4 50.0 0.0 0.0 30.0 20.0 0.0 0.0 

10/14/2005 128 USGS Alexandria 4 80.0 0.0 0.0 20.0 0.0 0.0 0.0 10/14/2005 129 USGS Alexandria 4 80.0 0.0 0.0 20.0 0.0 0.0 0.0 10/14/2005 130 USGS Alexandria 4 70.0 0.0 0.0 20.0 10.0 0.0 0.0 

10/14/2005 131 USGS Alexandria 2 40.0 0.0 50.0 5.0 5.0 0.0 0.0 

10/14/2005 132 USGS Alexandria 2 70.0 0.0 0.0 0.0 30.0 0.0 0.0 

10/14/2005 133 USGS Alexandria 4 50.0 0.0 0.0 25.0 25.0 0.0 0.0 

10/14/2005 134 USGS Alexandria 2 60.0 0.0 0.0 40.0 0.0 0.0 0.0 

28 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index. 

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

10/13/2005 135 USGS Quantico 4 70.0 10.0 10.0 10.0 0.0 0.0 0.0 0.10/13/2005 136 USGS Quantico 3 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

10/13/2005 137 USGS Quantico 4 20.0 0.0 0.0 75.0 5.0 0.0 0.0 0.

10/13/2005 138 USGS Quantico 4 0.0 0.0 0.0 100.0 0.0 0.0 0.0 0.

10/13/2005 139 USGS Quantico 4 30.0 0.0 0.0 50.0 20.0 0.0 0.0 0.

10/13/2005 140 USGS Quantico 3 0.0 0.0 90.0 10.0 0.0 0.0 0.0 0.

10/13/2005 141 USGS Quantico 4 80.0 0.0 5.0 10.0 5.0 0.0 0.0 0.

10/13/2005 142 USGS Quantico 2 33.0 0.0 0.0 34.0 33.0 0.0 0.0 0.

10/13/2005 143 USGS Quantico 3 60.0 0.0 0.0 30.0 10.0 0.0 0.0 0.

10/13/2005 144 USGS Quantico 1 30.0 0.0 0.0 50.0 20.0 0.0 0.0 0.

10/13/2005 145 USGS Quantico 3 55.0 20.0 20.0 5.0 0.0 0.0 0.0 0.

10/13/2005 146 USGS Quantico 3 30.0 5.0 25.0 20.0 20.0 0.0 0.0 0.

10/13/2005 147 USGS Quantico 3 90.0 0.0 10.0 0.0 0.0 0.0 0.0 0.

10/13/2005 148 USGS Quantico 3 10.0 5.0 75.0 5.0 5.0 0.0 0.0 0.

10/13/2005 149 USGS Quantico 4 50.0 10.0 10.0 0.0 30.0 0.0 0.0 0.

10/13/2005 150 USGS Quantico 4 60.0 0.0 0.0 10.0 30.0 0.0 0.0 0.

10/13/2005 151 USGS Quantico 3 15.0 0.0 50.0 5.0 30.0 0.0 0.0 0.

10/13/2005 152 USGS Quantico 3 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

10/13/2005 153 USGS Fort Belvoir 3 70.0 0.0 0.0 0.0 30.0 0.0 0.0 0.

10/13/2005 154 USGS Fort Belvoir 3 40.0 0.0 20.0 0.0 40.0 0.0 0.0 0.

10/13/2005 155 USGS Fort Belvoir 4 70.0 0.0 0.0 0.0 30.0 0.0 0.0 0.

10/13/2005 156 USGS Fort Belvoir 2 0.0 100.0 0.0 0.0 0.0 0.0 0.0 0.

10/13/2005 157 USGS Indian Head 4 70.0 20.0 0.0 10.0 0.0 0.0 0.0 0.

29 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index. 

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

10/4/2005 158 USGS Quantico 4 30.0 20.0 30.0 10.0 10.0 0.0 0.0 0.10/4/2005 159 USGS Quantico 3 60.0 20.0 5.0 15.0 0.0 0.0 0.0 0.10/4/2005 160 USGS Quantico 3 30.0 0.5 59.5 10.0 0.0 0.0 0.0 0.10/4/2005 161 USGS Quantico 4 5.0 30.0 60.0 5.0 0.0 0.0 0.0 0.

10/4/2005 162 USGS Quantico 3 10.0 0.0 80.0 0.0 0.0 0.0 10.0 0.10/4/2005 163 USGS Quantico 4 30.0 25.0 35.0 9.0 1.0 0.0 0.0 0.

10/4/2005 164 USGS Quantico 4 70.0 1.0 29.0 0.0 0.0 0.0 0.0 0.

10/4/2005 165 USGS Quantico 2 50.0 20.0 30.0 0.0 0.0 0.0 0.0 0.

10/4/2005 166 USGS Quantico 4 40.0 30.0 20.0 10.0 0.0 0.0 0.0 0.

10/4/2005 167 USGS Quantico 3 0.0 10.0 90.0 0.0 0.0 0.0 0.0 0.

10/4/2005 168 USGS Quantico 1 70.0 30.0 0.0 0.0 0.0 0.0 0.0 0.

10/4/2005 169 USGS Widewater 4 15.0 15.0 70.0 0.0 0.0 0.0 0.0 0.

10/4/2005 170 USGS Widewater 4 29.0 10.0 45.0 10.0 5.0 0.0 1.0 0.10/4/2005 171 USGS Widewater 4 30.0 10.0 55.0 5.0 0.0 0.0 0.0 0.

10/4/2005 172 USGS Widewater 4 69.0 10.0 10.0 5.0 5.0 0.0 1.0 0.

10/4/2005 173 USGS Widewater 4 10.0 10.0 80.0 0.0 0.0 0.0 0.0 0.

10/4/2005 174 USGS Widewater 2 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

10/4/2005 175 USGS Widewater 4 70.0 0.0 0.0 15.0 15.0 0.0 0.0 0.

10/4/2005 176 USGS Widewater 3 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

10/4/2005 177 USGS Widewater 4 0.0 70.0 30.0 0.0 0.0 0.0 0.0 0.10/4/2005 178 USGS Widewater 3 0.0 10.0 90.0 0.0 0.0 0.0 0.0 0.10/4/2005 179 USGS Widewater 4 0.0 15.0 40.0 5.0 0.0 0.0 0.0 40

10/4/2005 180 USGS Widewater 3 0.0 5.0 95.0 0.0 0.0 0.0 0.0 0.

30 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each sabbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologic

is DC Dept. of Health. Div is Shannon diversity index. 

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

10/4/2005 181 USGS Widewater 4 5.0 15.0 40.0 10.0 0.0 30.0 0.0 0.10/4/2005 182 USGS Widewater 4 0.0 90.0 10.0 0.0 0.0 0.0 0.0 0.

9/29/2005 183 USGS Quantico 3 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

9/29/2005 184 USGS Indian Head 3 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

9/29/2005 185 USGS Indian Head 4 40.0 10.0 20.0 20.0 10.0 0.0 0.0 0.

9/29/2005 186 USGS Indian Head 4 20.0 60.0 5.0 10.0 5.0 0.0 0.0 0.

9/29/2005 187 USGS Indian Head 4 5.0 49.5 0.5 45.0 0.0 0.0 0.0 0.

9/29/2005 188 USGS Indian Head 4 10.0 50.0 9.0 30.0 0.0 1.0 0.0 0.9/29/2005 189 USGS Indian Head 3 10.0 40.0 10.0 35.0 5.0 0.0 0.0 0.9/29/2005 190 USGS Indian Head 4 9.0 1.0 0.0 19.0 0.0 70.0 1.0 0.

9/29/2005 191 USGS Indian Head 4 10.0 15.0 65.0 5.0 0.0 0.0 5.0 0.9/29/2005 192 USGS Indian Head 1 0.0 10.0 60.0 20.0 0.0 0.0 10.0 0.9/29/2005 193 USGS Indian Head 3 0.0 5.0 95.0 0.0 0.0 0.0 0.0 0.

9/29/2005 194 USGS Indian Head 2 0.0 25.0 60.0 10.0 0.0 0.0 5.0 0.9/29/2005 195 USGS Indian Head 4 50.0 20.0 20.0 5.0 5.0 0.0 0.0 0.9/29/2005 196 USGS Indian Head 4 70.0 1.0 0.0 0.0 29.0 0.0 0.0 0.

9/29/2005 197 USGS Indian Head 4 30.0 10.0 40.0 10.0 10.0 0.0 0.0 0.9/29/2005 198 USGS Indian Head 4 45.0 10.0 5.0 25.0 15.0 0.0 0.0 0.9/28/2005 199 USGS King George 1 0.0 0.0 0.0 100.0 0.0 0.0 0.0 0.

9/28/2005 200 USGS Passapatanzy 4 40.0 10.0 0.0 10.0 0.0 0.0 40.0 0.

9/28/2005 201 USGS Passapatanzy 3 50.0 0.0 0.0 5.0 35.0 10.0 0.0 0.

9/28/2005 202 USGS Passapatanzy 1 80.0 0.0 0.0 0.0 20.0 0.0 0.0 0.

9/28/2005 203 USGS Passapatanzy 4 80.0 0.0 0.0 0.0 20.0 0.0 0.0 0.

31 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index. 

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

9/28/2005 204 USGS Passapatanzy 3 50.0 1.0 9.0 10.0 30.0 0.0 0.0 0.9/28/2005 205 USGS Passapatanzy 3 50.0 0.0 0.0 0.0 50.0 0.0 0.0 0.

9/28/2005 206 USGS Passapatanzy 4 64.5 10.0 0.0 10.0 15.0 0.5 0.0 0.

9/28/2005 207 USGS Passapatanzy 3 0.0 100.0 0.0 0.0 0.0 0.0 0.0 0.9/28/2005 208 USGS Passapatanzy 4 59.5 10.0 5.0 10.0 15.0 0.0 0.5 0.

9/28/2005 209 USGS Passapatanzy 1 0.5 96.5 1.0 1.0 0.0 0.0 1.0 0.

9/28/2005 210 USGS Passapatanzy 4 7.0 79.0 0.0 7.0 7.0 0.0 0.0 0.

9/28/2005 211 USGS Passapatanzy 1 0.0 0.0 0.0 100.0 0.0 0.0 0.0 0.

9/28/2005 212 USGS Widewater 4 1.0 96.0 1.0 1.0 1.0 0.0 0.0 0.

9/28/2005 213 USGS Widewater 4 0.0 44.0 1.0 55.0 0.0 0.0 0.0 0.

9/28/2005 214 USGS Widewater 4 40.0 40.0 5.0 5.0 9.5 0.0 0.5 0.

9/28/2005 215 USGS Widewater 4 49.0 40.0 0.5 5.0 5.0 0.0 0.5 0.

9/28/2005 216 USGS Widewater 4 59.5 30.0 0.5 5.0 5.0 0.0 0.0 0.

9/28/2005 217 USGS Widewater 3 1.0 87.0 1.0 10.0 1.0 0.0 0.0 0.9/28/2005 218 USGS Widewater 4 92.0 2.0 2.0 2.0 2.0 0.0 0.0 0.

9/28/2005 219 USGS Widewater 4 79.0 20.0 0.0 0.0 1.0 0.0 0.0 0.

9/27/2005 220 USGS Indian Head 2 5.0 0.0 95.0 0.0 0.0 0.0 0.0 0.

9/27/2005 221 USGS Indian Head 3 0.0 5.0 95.0 0.0 0.0 0.0 0.0 0.

9/27/2005 222 USGS Indian Head 1 4.0 85.0 10.0 1.0 0.0 0.0 0.0 0.

9/27/2005 223 USGS Indian Head 3 10.0 10.0 35.0 35.0 10.0 0.0 0.0 0.9/27/2005 224 USGS Indian Head 1 0.0 9.0 90.0 1.0 0.0 0.0 0.0 0.

9/27/2005 225 USGS Indian Head 3 5.0 10.0 50.0 10.0 10.0 0.0 15.0 0.9/27/2005 226 USGS Indian Head 4 15.0 15.0 30.0 5.0 35.0 0.0 0.0 0.

32 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index.

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

9/27/2005 227 USGS Indian Head 4 70.0 10.0 5.0 5.0 10.0 0.0 0.0 0.9/27/2005 228 USGS Indian Head 1 8.0 90.0 0.0 2.0 0.0 0.0 0.0 0.

9/27/2005 229 USGS Indian Head 3 17.0 17.0 30.0 1.0 35.0 0.0 0.0 0.

9/27/2005 230 USGS Indian Head 4 17.0 17.0 30.0 1.0 35.0 0.0 0.0 0.

9/27/2005 231 USGS Indian Head 4 50.0 4.0 2.0 22.0 20.0 0.0 2.0 0.

9/27/2005 232 USGS Indian Head 4 30.0 10.0 40.0 0.0 20.0 0.0 0.0 0.

9/27/2005 233 USGS Port Tobacco 4 52.0 4.0 2.0 22.0 20.0 0.0 0.0 0.

9/27/2005 234 USGS Port Tobacco 4 30.0 10.0 40.0 0.0 20.0 0.0 0.0 0.

9/27/2005 235 USGS Mt. Vernon 4 52.0 4.0 2.0 22.0 20.0 0.0 0.0 0.

9/27/2005 236 USGS Mt. Vernon 4 50.0 0.0 50.0 0.0 0.0 0.0 0.0 0.

9/27/2005 237 USGS Mt. Vernon 4 45.0 0.0 30.0 0.0 0.0 0.0 25.0 0.

9/27/2005 238 USGS Mt. Vernon 4 48.0 2.0 10.0 10.0 20.0 3.0 7.0 0.

9/27/2005 239 USGS Mt. Vernon 1 5.0 85.0 0.0 5.0 5.0 0.0 0.0 0.9/27/2005 240 USGS Mt. Vernon 4 15.0 20.0 5.0 39.0 20.0 0.0 1.0 0.

9/27/2005 241 USGS Mt. Vernon 4 40.0 10.0 0.0 10.0 40.0 0.0 0.0 0.

9/27/2005 242 USGS Mt. Vernon 1 5.0 85.0 0.0 5.0 5.0 0.0 0.0 0.9/27/2005 243 USGS Mt. Vernon 4 25.0 5.0 5.0 25.0 25.0 0.0 15.0 0.9/22/2005 244 USGS Mattawoman Cr. 4 90.0 1.0 0.0 5.0 4.0 0.0 0.0 0.

9/22/2005 245 USGS Mattawoman Cr. 4 20.0 5.0 60.0 10.0 5.0 0.0 0.0 0.

9/22/2005 246 USGS Mattawoman Cr. 4 5.0 0.0 15.0 0.0 80.0 0.0 0.0 0.

9/22/2005 247 USGS Mattawoman Cr. 4 95.0 0.0 5.0 0.0 0.0 0.0 0.0 0.

9/22/2005 248 USGS Mattawoman Cr. 4 5.0 3.0 30.0 2.0 60.0 0.0 0.0 0.

9/22/2005 249 USGS Mattawoman Cr. 4 30.0 0.0 0.0 70.0 0.0 0.0 0.0 0.

33 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index. 

Survey 

date 

Field bed

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

9/22/2005 250 USGS Mattawoman Cr. 4 65.0 5.0 20.0 5.0 5.0 0.0 0.0 0.9/22/2005 251 USGS Mattawoman Cr. 4 60.0 15.0 20.0 5.0 0.0 0.0 0.0 0.

9/22/2005 252 USGS Mattawoman Cr. 4 5.0 0.0 30.0 5.0 60.0 0.0 0.0 0.

9/22/2005 253 USGS Mattawoman Cr. 4 80.0 20.0 0.0 0.0 0.0 0.0 0.0 0.9/22/2005 254 USGS Mattawoman Cr. 4 88.0 4.0 2.0 5.0 1.0 0.0 0.0 0.

9/22/2005 255 USGS Mattawoman Cr. 4 70.0 0.0 25.0 5.0 0.0 0.0 0.0 0.9/22/2005 256 USGS Mattawoman Cr. 4 50.0 50.0 0.0 0.0 0.0 0.0 0.0 0.9/22/2005 257 USGS Mattawoman Cr. 4 30.0 10.0 0.0 50.0 10.0 0.0 0.0 0.

9/22/2005 258 USGS Mattawoman Cr. 4 48.0 48.0 4.0 0.0 0.0 0.0 0.0 0.9/22/2005 259 USGS Mattawoman Cr. 4 0.0 50.0 0.0 35.0 15.0 0.0 0.0 0.

9/22/2005 260 USGS Mattawoman Cr. 4 30.0 25.0 5.0 40.0 0.0 0.0 0.0 0.

9/22/2005 261 USGS Mattawoman Cr. 4 0.0 99.0 1.0 0.0 0.0 0.0 0.0 0.

9/22/2005 262 USGS Mattawoman Cr. 4 75.0 0.0 0.0 20.0 5.0 0.0 0.0 0.

9/22/2005 263 USGS Mattawoman Cr. 2 0.0 5.0 95.0 0.0 0.0 0.0 0.0 0.

9/22/2005 264 USGS Mattawoman Cr. 4 20.0 40.0 10.0 20.0 10.0 0.0 0.0 0.

9/22/2005 265 USGS Mattawoman Cr. 3 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.9/22/2005 266 USGS Mattawoman Cr. 3 0.0 30.0 70.0 0.0 0.0 0.0 0.0 0.9/16/2005 267 DOH Alexandria 1 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

9/30/2005 268 DOH DC West 2 95.0 0.0 0.0 0.0 5.0 0.0 0.0 0.

9/28/2005 269 DOH DC West 2 98.0 0.0 0.0 0.0 2.0 0.0 0.0 0.

9/21/2005 270 DOH DC West 1 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

9/21/2005 271 DOH DC West 1 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

9/30/2005 272 DOH DC West 1 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

34 
Table 1 – continued. Percent canopy cover of each species and Shannon diversity index for field 

continuously along the shoreline in the tidal Potomac River, 2005. Field bed numbers correspond 

Figs. 5 to 11. Density classes are USGS field data based on a Braun-Blanquet crown cover mode10 %, 2 = 11 to 40 %, 3 = 41 to 70 %, and 4 = 71 to 100 % cover. Percent cover of each s

abbreviated as: P_HV (hydrilla), P_MS (milfoil), P_VA (wild celery), P_CD (coontail), P_NM (naiad)naiad), P_HD (stargrass), P_SP (sago pondweed), and P_CV (muskgrass). USGS is U.S. Geologicis DC Dept. of Health. Div is Shannon diversity index. 

Survey 

date 

Field 

bed 

number 

Data 

source USGS quad Density class P_HV P_MS P_VA P_CD P_NM P_NGU P_HD 

9/30/2005 273 DOH DC West 3 99.0 0.0 0.0 0.0 0.0 0.0 1.0 0.9/30/2005 274 DOH DC West 3 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

9/30/2005 275 DOH DC West 4 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

9/28/2005 276 DOH DC West 1 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

9/21/2005 277 DOH DC West 1 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

9/28/2005 278 DOH Alexandria 4 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.9/15/2005 279 DOH Alexandria 2 98.0 0.0 0.0 0.0 2.0 0.0 0.0 0.

9/21/2005 280 DOH 

Alexandria/ DC West 2 0.0 0.0 100.0 0.0 0.0 0.0 0.0 0.

10/3/2005 281 DOH Alexandria 1 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.10/3/2005 282 DOH Alexandria 2 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.

8/30/2005 283 DOH Alexandria 2 55.0 0.0 0.0 0.0 45.0 0.0 0.0 0.

10/3/2005 284 DOH Alexandria 2 90.0 0.0 5.0 0.0 4.0 0.0 1.0 0.

10/3/2005 285 DOH Alexandria 1 95.0 0.0 0.0 0.0 5.0 0.0 0.0 0.

10/4/2005 286 DOH Alexandria 1 99.0 0.0 0.0 0.0 1.0 0.0 0.0 0.

10/13/2005 287 DOH Alexandria 1 100.0 0.0 0.0 0.0 0.0 0.0 0.0 0.10/17/2005 288 DOH Alexandria 1 95.0 0.0 0.0 0.0 5.0 0.0 0.0 0.

8/29/2005 289 DOH Alexandria 1 69.5 0.0 0.5 1.0 29.0 0.0 0.0 0.

10/4/2005 290 DOH Alexandria 1 90.0 0.0 0.0 5.0 5.0 0.0 0.0 0.

10/17/2005 291 DOH Alexandria 2 50.0 0.0 35.0 15.0 0.0 0.0 0.0 0.

35