ROOTED AQUATIC PLANTS IN THE UPPER POTOMAC RIVER BASIN DIVISION OF FIELD INVESTIGATIONS, CINCINNATI OFFICE OF ENFORCEMENT AND STANDARDS COMPLIANCE WATER QUALITY OFFICE ENVIRONMENTAL PROTECTION AGENCY CINCINNATI, OHIO ------- ROOTED AQUATIC PLANTS IN THE UPPER POTOMAC RIVER BASIN by Delbert B. Hicks Division of Field Investigations, Cincinnati Office of Enforcement and Standards Compliance Water Quality Office Environmental Protection Agency Cincinnati, Ohio 1971 ------- TABLE OF CONTENTS CONCLUSIONS 1 INTRODUCTION 2 STUDY AREA 3 SAMPLING STATION AND METHODS h AQUATIC PLANT GROWTH FACTORS 5 STUDY RESULTS 6 SIGNIFICANCE OF ROOTED AQUATIC PLANTS AS RESERVOIRS OF NUTRIENTS' 9 ACKNOWLEDGEMENTS . 10 LITERATURE CITED 11 TABLES Table 1. Location of Aquatic Plant Sampling Stations, Upper Potomac River Basin. ... . . Follow Page 9 Table 2. Standing Crop of Root Aquatic Plants in the Upper Potcmac River Basin and Weight of Phosphorus and Organic Nitrogen in Storage . . . Table 3. Phosphorus and Nitrogen Content of Rooted Aquatic Plants from the Upper Potcmac River Basin ------- CONCLUSIONS 1. Rooted aquatic plants in the Upper Potomac Basin axe not a significant factor in the nutrient budget of the Lover Potomac River. 2. In August 1969 the standing crop of rooted aquatic plants in the Upper Potomac River Basin contained 400 pounds of phosphorus (P) and pounds of nitrogen (N). These quantities are equivalent to approximately 40 percent of the phosphorus and nitrogen in wastewaters discharged to the Upper Potomac River in a single day. 5- Standing crop estimates were made for growths in Antietam Creek, Conococheague Creek and the Potomac River. Other basin streams contained too few growths of rooted plants to merit sampling for standing crop estimates. 1 ------- INTRODUCTION Conferees of the Potomac River-Washington Metropolitan Area Enforcement Conference recommended that the Interstate Commission on the Potomac River Basin, the States of Maryland, Virginia, Pennsylvania and West Virginia, the District of Columbia and the Federal Water Pollution Control Administration make joint studies of the entire Potomac Basin to determine detrimental effects on the Potomac River and estuary. Concern developed for the effects of rooted aquatic plants or pond-weeds on the nutrient regimen cf the Lower Potomac River and estuary. These plants accumulate and store nutrients during the spring and summer growing season. Upon death and decay of these plants in late summer and autumn, stored nutrients would be released for transport to the lower river and estuary where nuisance algal growths occur. The Regional Director, Middle Atlantic Region, Federal Water Pollution Control Administration, requested the Division of Field Investigations, Cincinnati, to conduct a study of plants in the Upper Potomac River Basin to: 1. Estimate the quantity of phosphorus (p) and organic nitrogen (N) accumulated in rooted aquatic plant growth. 2. Assess the significance of these stored nutrients on the nutrient budget of the Potomac River Basin. 2 ------- STUDY AREA The Potomac River portion included in the study ex- tended from Great Falls, Maryland, upstream 220 miles to the confluence of the Savage River, Maryland. Major tributary streams investigated were the Monocacy River, Antietam Creek, Conococheague Creek, South Branch Potomac River, Cacapon River, and Shenandoah River. The field survey was conducted August 11 to 19, 19^9> a period of the year when aquatic plant6 growths would be expected to reach maximum abundance. 5 ------- SAMPLING STATION AND METHODS When possible, sampling stations were located near highway bridge crossings. Bridges provided good vantage points to observe the overall streambed coverage by rooted aquatic plants. For purpose of study, rooted aquatic plants were defined as vascular plants attached to the stream bottom by a root system and submerged except for floating portions of the plants and the macro-alga Chara. The quantity of rooted aquatic plants was determined when plant growths covered more than five percent of the stream bottom. The percent coverage and quantity of plants for the interstation reaches were estimated by extrapolation. Fifty sampling stations were established in the study area (Figure 1 and Table l). Plant samples were taken with an open-ended, steel cylinder, 10 inches in diameter and 36 inches in length. The sampler was forced into the 6tream bottom with a rotary motion. Entrapped vegetation was removed, damp dried, segregated into species and weighed. Sampling was conducted at 20-foot intervals along a 100- foot transect of the plant growths. Complete plants representative of the kinds found in the quantitative samples were collected, damp-dried, weighed, frozen on dry ice, and returned to the laboratory. Each specimen was homogenized, freeze-dried, and analyzed for phosphorus (P) and organic nitrogen (N) content. 4 ------- POTOMAC RIVER BASIN ------- AQCJATIC PLAM* GROWTH FACTORS The establishment and growth of rooted aquatic plants is governed by physical factors such as the availability of suit- able substratej current velocities, water depth and turbidity. Increased current velocity can cause the bottom to become physically unstable for root attachment by scouring away the finer particles in which plants root. Increases in depth or turbidity reduces available sunlight for plant germination and photosynthesis. If adverse conditions persist into the growing season, lush growths may fail to develop in areas that in previous years may have supported abundant growths. Phosphorus and nitrogen sure two major nutrients essential for growth of rooted aquatic plants. Plants assimilate these nutrients and place them in temporary storage. The quantities of nutrients held in storage are dependent upon the standing crop of plants. With the annual die-down of plants in the fall, stored nutrients are slowly released to the stream as plants undergo de- composition. The released nutrients are then available for recycling by other primary producers. 5 ------- STUDY RESULTS UPPER POTOMAC RIVER The main stem of the Upper Potomac River upstream from the Great Falls supported a standing crop of rooted aquatic plants estimated at TOO tons and contained 280 pounds of phos- phorus (P) and 3660 pounds of nitrogen (N) (Table 2). Sixty- six percent of the standing crop was contained in an 18 mile reach extending from the confluence of Antietam Creek (Station 17) upstream to where Conococheague Creek enters the Potcmac River. The remaining portion of the standing crop was in a 35-mile section of the river extending from the mouth of the South Branch Potomac River upstream to Dawsen, Maryland. ANTIETAM CREEK Antietam Creek, Maryland had an estimated 5k tons of rooted aquatic plants with a potential yield of 3*+ pounds phos- phorus and 220 pounds nitrogen (Table 2). Fifty-three percent of the plants were found in two 600-foot sections of Antietam Creek: 1. at Burnside Bridge (Station 13) near Sharpsberg and 2. at Antietam (Station 17) near the mouth of the stream. These two very dense patches of plants were atypical for the stream. 6 ------- 7 At these points, the stream was shallow and uniform in depth, lacked shading by upper-story stream-side vegetation and supported one species of rooted aquatic vegetation. Thirty-six percent of the aquatic weeds were contained in a 15-mile reach extending downstream from the mouth of the West Branch of Antietam Creek. The West Branch (Station 13A) supported 11 percent of the standing crop in a one-mile reach of stream flowing through a meadow. The East Branch of Antietam Creek (Station lk) supported too few plants for determining standing crop estimates. CONOCOCHEAGUE CREEK Conococheague Creek supported an estimated 128 tons of rooted aquatic plants that contained 80 pounds of phosphorus (p) and 520 pounds of nitrogen (N) (Table 2). The plants were dis- tributed in an eight-mile section of stream located at Station 19- MONOCACY RIVER, SOUTH BRANCH POTOMAC RIVER, SHENANDOAH RIVER, AND CACAPON RIVER These streams and their tributaries contained insufficient growths of rooted aquatic plants from which standing crop estimates could be determined. Aquatic plant coverage was less than five percent. Streams had high flows which were considered unseasonable ------- 8 for the year because of heavy summer rains. The streams and their tributaries were very turbid with visibility reduced to less them 12 inches in depth. High flows and increased tur- bidity were apparent factors limiting the abundance of rooted aquatic plants in these streams. ------- SIGNIFICANCE OF ROOTED AQUATIC PLANTS AS RESERVOIRS OF NUTRIENTS Rooted aquatic plants in the Potomac River Basin are not a significant factor affecting nutrient loading of the Lower Potomac River. The August standing crop of rooted aquatics in the Potomac River upstream from the Great Falls was estimated to be 880 tons and contained 400 pounds phosphorus (P) and M*00 pounds nitrogen (N). These nutrients are equivalent to approximately UO percent of the average total pounds of phosphorus and nitrogen in waste- waters discharged to the Upper Potomac River system in a single day w. In past years, more extensive growths of rooted aquatic (2 3 1<.) plants in the Upper Basin have been reportedv ' ' ' . Even under conditions of a superabundance of rooted aquatic plants, the quantity of phosphorus and nitrogen in storage remains insignificant when compared to the known nutrient discharges. Assuming that stream beds of the Upper Potomac River and its major tributaries were 100 percent covered with plants at densities equal to the maximum observed in this study, total phosphorus and nitrogen in storage would be less than .04 percent and 2.0 percent, respectively, of that discharged annually to the Lower Potomac River as measured at the Great Falls. 9 ------- Table 1. Location of Aquatic Plant Sampling Stations, Upper Potomac River Basin Station No. Stream Location 11 Monocacy River Md. Rt. 28 Bridge 10 Monocacy River Lily Pons Bridge, Gland Road, Md. 9 Monocacy River Md. Rt. 80 Bridge east of Buckeystown, Md. 8 Monocacy River Gas House Pike Road Bridge near Frederick, Md. 7 Monocacy River Md. Rt. 26 Bridge at Ceresville, Md. 6 Monocacy River Md. Rt. 76 Bridge (Le Gore Bridge) 5 Monocacy River Mumma Ford Bridge, Md. k Monocacy River West of Harvey, Md. 5 Marsh Creek Greenmount, Pa. 2 Rock Creek Pa. Rt. 13k Bridge at Barlow, Pa. IT Antietam Creek Antietam, Md. 13 Antietam Creek Burnside Bridge, Antietam Nat. Park, Md. 16 Antietam Creek Roxbury Road Bridge, Md. 15 Antietam Creek Md. 60 Bridge Ik £. Branch Antietam Creek Pa. Rt. 16 Bridge, east of Waynesboro, Pa. 1JA W. Branch Antietam Creek Pa. Rt. 516, northwest of Waynesboro, Pa. 18 Conococheague Creek Md. Rt. 68 Bridge, near mouth 19 Conococheague Creek Conococheague, Md. 20 Conococheague Creek Broadfording Road Bridge, Md- 21 Conococheague Creek Pa. Rt. l6 Bridge west of Greencastle, Pa. ------- Table 1 Cont. Station No. Stream Location 26 Potomac River Md. Rt. 135 at mouth Savage R., Md. 27 Potomac River Md. Rt. 9 near Pinto, Md. 29 Potomac River Toll Bridge at Old Town, Md. 2k Potomac River W. Va. Rt. 29 Bridge at Paw Paw, W. Va. 52 Potomac River W. Va. Rt. 48 Bridge at Sheperdstown, W. Va. 50 Potomac River Harpers Ferry, W. Va. 53 Potomac River Md. Rt. 15 Bridge at Pt. Rocks, Md. 57 Potomac River Great Falls, Cheaapeake and Ohio Canal Park, Md. 30 S. Branch, Potomac R. French Sta. W. Va. near mouth 31 S. Branch Potomac R. W. Va. Rt. 28 Bridge downstream Romney, W. Va. 32 S. Branch Potomac R. W. Va. Rt. 28 Bridge upstream Romney, W. Va. 33 S. Branch Potomac R. U.S. 220 Bridge downstream Moorefield, W. Va. 35 S. Branch Potomac R. U.S. 220 Bridge downstream Petersburg, W. Va. 36 S. Branch Potomac R. 1 mile downstream Petersburg, W. Va. 37 S. Branch Potomac R. U.S. 220 Bridge upstream Petersburg, W. Va. 39 s- Branch Potomac R. U.S. 33 Bridge E. of Franklin, W. Va. 38 N. Fork of S. Branch U. S. 35 Bridge at Judy Gap, W. Va. Potomac River ------- Table 1 Cont. Station No • Stream JU S. Fork of S. Branch, Potomac River UO S. Fork of S. Branch, Potomac River 22 Cacapon River 23 Cacapon River k9 Shenandoah River U8 Shenandoah River k6 S. Fork Shenandoah River bk S. Fork Shenandoah River i+3 South River of S. Fork Shenandoah River k2 Middle River of S. Fork Shenandoah River kl North River of S. Fork Shenandoah River kj North Fork Shenandoah River 1*5 North Fork Shenandoah River Location U.S. 220 Bridge at Moorefield, W. Va. U. S. 33 Bridge near Brandyvine, W.Va. W.Va. Rt. 9 Bridge near mouth W.Va. Rt. 9> 2nd Bridge upstream from mouth Harpers Ferry National Park, W.Va. Va. Rt. 7 Bridge east of Berryville, Va. Va. Rt. 211 Bridge west of Luray, Va. Va. Rt. 33 Bridge east of Elkton, Va. Va. Rt. 256 at Grottoes, Va. Va. Rt. 256 east of Weyers Cave, Va U. S. 11 Bridge south Mt. Crawford, Va. Va. Rt. 55 Bridge Va. Rt. U2 Bridge at Timberville, Va. ------- Table 2. Standing Crop of Root Aquatic Plants In the Upper Potomac River Basin and Weight of Phosphorus and Organic Nitrogen in Storage Tons2 Weeds per Strean Mi. Plants Contained] Stream Sta. No. Mi. of Stream1 Aver. Stream Width, Ft. $ Weed Coverage lbs2 Weeds per S^.Ft. lbs P per Streasi Mi. lbs N per Stream Mi. . Potomac River 52 18 550 20 .09 26 10 102 ti 27 18 105 20 •09 5 2 13 If 29 17 185 30 .06 9 1+ 1*0 Antietam Ck. 17 0.1 125 80 •51 15 8 ko ti 15 0.1 110 80 • 51 13 7 35 M 16 17 75 < 5 - - - - fl 15 15 •F* vn 15 .07 1 1 7 II 13A 1 15 30 • 50 6 36 II ll* - 20 < 5 - - - - Conococheague Ck. 18 fc-5 150 < 5 - - - - It 19 8 200 30 .10 16 10 55 II 20 11+ 125 < 5 - - - - fl 21 - 100 < 5 - - - — es of stream estimated as representative of data. Stet weight ^Nutrient data based on phosphorus and nitrogen analyses of plant types present at sampling station (Table 3)• ------- Table 3¦ Phosphorus and Nitrogen Content of Rooted Aquatic Plants from the Upper Potcmac River Basin pTof~TotaI Wet Wt- Dry Vt. Station Kinds of Plants Weeds at Nutrient Nutrient $ P $ P $N % H No- from Sq. Ft. Sample Station Sample(gm) SampLe(gjn) Dry Vt. Vet Vt. Dry Vt. Vet . 13 Heterantherla dubi 100 28 1-59 0.44 0.025 2.4 0.13 13A Elodea canadensis 94 30 4.28 0.25 0.035 2.1 0.30 Potamogeton crispus 6 31 2.98 0.29 0.028 2.2 0.21 15 E. canadensis 67 42 3-78 O.56 0-050 3-0 0.27 H. dubi 13 12 1.22 0.48 0.049 2.7 0.27 19 H. dubi 69 25 2.10 0.36 0.030 1-9 0.16 P. americamifl 16 13 1.57 0-30 0.036 2.0 0.24 E. canadensis 15 18 1.83 O.36 0.030 1-7 0.17 28 Najas flexilis 46 14 1.76 O.17 0.021 1.1 0.14 H. dubi 29 17 1.30 0.14 0.010 1.8 0.14 Chara sp. 10 5 0.93 0.12 0.022 0.8 0.15 E. canadensis 5 6 1.11 0.10 0.018 0.0 0.14 29 P. illinoens is 59 16 1.87 0.24 0.028 2.2 0.25 P. diverBifollus 41 22 3-03 0.12 0.016 1.4 0.19 52 Vallisneria sp. 74 24 1.86 0.19 0.015 2.2 0.17 H. dubi 11 13 1.03 0.30 0.024 2.6 O.25 P. illinoens is 8 24 2.87 0.22 0.027 2.2 0.24 N. Ruadalupensis 4 14 1.77 0.28 O.O36 2.6 0-33 E. canadensis 3 7 1.30 0.14 0.026 1.8 0.33 ------- ACKNOWLEDGEMENTS James LaBuy, Aquatic Biologist, Middle Atlantic Region, EPA, Charlottesville, Virginia, assisted with field investi- gations . Chemists, Division of Field Investigations, Cincinnati, EPA, Cincinnati, Ohio, conducted plant nutrient analyses. 10 ------- LITERATURE CITED 1. Javorski, N. A., D. W. Lear, and J. A. Aalto. A Technical Assessment of Current Water Quality Conditions and Factors Affecting Water Quality in the Upper Potomac Estuary. Tech. Rept. No. 3} Chesapeake Technical Support Laboratory, Middle Atlantic Region, PVPCA, Dept. of Interior. 19^9 • 2. DeRose, C. R. The Monocacy River, Physical, Chemical and Bacteriological Water Quality, Rept. No. 1, State of Maryland, Dept. of Water Resources, Division of Water Quality Investi- gations. 1966. 3. LaBuy, J. Biological Survey of the Monocacy River and Tributaries. CB-SRBP Working Docunent No. 2J, Middle Atlantic Region, FWPCA, Dept. of Interior. 1968. LaBuy, J. Biological Survey Antietam Creek and Some Tribu- taries. CB-SRBP Working Document No. 22, Middle Atlantic Region, JVPCA, Dept. of Interior. 1968. 11 ------- Rooted aquatic plants in the upper Potomac River basin EJDD PT 00027 ------- |