The purpose of this project was to identify pollutant loading values which might be used as input for a series of water quality models applied to small tidal creeks and inlets in Virginia\u27s coastal plain. The intent was to identify values from literature sources which might be used in application of the models, absent better or more site specific information. Estimates of biological oxygen demand, chemical oxygen demand and fecal coliform loadings were of specific interest

Greiner, Megan K.

Hershner, Carl H.

Neilson, Bruce J.

English

College of William & Mary: W&M Publish

W&M ScholarWorks Reports 1995 Modeling cumulative impacts and the carrying capacity of small tidal creeks and inlets Bruce J. Neilson Virginia Institute of Marine Science Carl H. Hershner Virginia Institute of Marine Science Megan K. Greiner Virginia Institute of Marine Science Follow this and additional works at: https://scholarworks.wm.edu/reports  Part of the Environmental Monitoring Commons Recommended Citation Neilson, B. J., Hershner, C. H., & Greiner, M. K. (1995) Modeling cumulative impacts and the carrying capacity of small tidal creeks and inlets. Virginia Institute of Marine Science, William & Mary. https://doi.org/10.25773/cy7y-z029 This Report is brought to you for free and open access by W&M ScholarWorks. It has been accepted for inclusion in Reports by an authorized administrator of W&M ScholarWorks. For more information, please contact scholarworks@wm.edu. Modeling Cumulative Impacts and the Carrying Capacity of Small Tidal Creeks and Inlets Bruce J. Neilson Carl Hershner Megan Greiner Virginia Institute of Marine Science School of Maiine Science College of William and Mary Gloucester Point, Virginia 23062 SEP 1 1995 This report was.fimded, in part by the Depar/111ent <if Environmental Quality's Coastal Resources Management Program through Grant #NA470Z0287-0l <if the National Oceanic and Atmospheric Administration, Office of Ocean and Coastal Resource Management, under the Coastal Zone Management Act <if 1972, as amended. Vlms 1"0 4-~3 hs4 ,q9c Modeling Cumulative Impacts and the Carrying Capacity of Small Tidal Creeks and Inlets INTRODUCTION Estimation of water quality impacts associated with use changes on land or water is primarily dependent on knowledge of what will be added to the water as a consequence of the change in use. Understanding of the mixing and transport of substances added to water bodies is reasonably advanced, with numerous mathematical models available to generate assessments of dilution and dispersion. The accuracy of model output is constrained, however, by the accuracy of the estimates of what is being added to the water (loadings). Frequently, loading of pollutants is unknown and extremely difficult to measure. When pollutant loading occurs as a result of point source discharge, measurement of amounts added can be determined if concentrations and flow rates are known. While not a trivial problem, it is usually possible to mount an outfall sampling program sufficient to generate the required estimate. The problem is much more intractable when dealing with nonpoint source pollution. Addition of nutrients, sediments, biological and chemical oxygen demand, fecal coliforms and other substances to water bodies from surrounding lands is generally variable in both time and space. Estimating a time and space averaged loading is a difficult undertaking requiring extensive long term sampling of all the various delivery pathways. Few studies have undertaken the comprehensive sampling necessary to generate such numbers. Even w~en estimates of pollutant loadings are developed, application of the estimates to 1 areas outside of the original sampling site entails an enormous number of assumptions about modes and rates of delivery, assumptions which are rarely documented or tested. As a consequence, prediction of water quality impacts, and particularly cumulative impacts, remains a speculative undertaking. Model output can be no better than the quality of the data used as input. The purpose of this project was to identify pollutant loading values which might be used as input for a series of water quality models applied to small tidal creeks and inlets in Virginia's coastal plain. The intent was to identify values from literature sources which might be used in application of the models, absent better or more site specific information. Estimates of biological oxygen demand, chemical oxygen demand and fecal coliform loadings were of specific interest FINDINGS Numerous studies have sought to determine pollutant loads associated with different land uses through intensive field work and long term sampling ( eg. Clesceri et al., 1986; Beulac et al. 1982; Sonzogni, 1980). The majority of these works measure pollutant input through surface runoff following rainfall events. Runoff export coefficients are calculated as average annual pollutant loads per unit area. There are several limitations to braod application of these values. While studies have suggested that land use is the most important factor controlling pollutant loads in runoff waters (eg. Rast et al. 1983, Whipple et al. 1978), the net input of pollutants is understood to be a result of rainfall intensity and frequency, soil type, watershed slopes, and small scale patterns of land cover/use. Transport through groundwater pathways is also understood to be locally important and highly variable. Incorporation of all of these considerations in water quality models, while an objective of ongoing work, is not yet practical. Current models, and particularly those developed in the related work for this project, rely primarily on measures of land use and a generalized runoff coefficient Uttorm~ et al. (1974) concluded from a survey of literature that there is little 2 justification for the delineation of land useage beyond categories of urban, agriculture, forest and pasture. Thus, most studies report values for these classes of land uses. A survey of the literature indicates loading values can vary widely, generally over one to two order of magnitude for any single pollutant and land use type. This report provides a summary of values for both runoff coefficients (TABLE 1) and storm water runoff load estimates (TABLE 2) for total suspended solids, biological oxygen demand, coliform levels, chemical oxygen demand, total nitrogen and total phosphorus. SPECIAL NOTE FOR FECAL COLIFORMS Estimation of fecal coliform loadings is particularly important in efforts to evaluate projects proposing marina construction. At the present time, the number of boat slips available in a marina is used as a predictor of probable pathogen concentrations in surrounding waters. The purpose of this determination is to set shellfish harvest controls, hopefully preventing the harvest and/or marketing of shellfish which might contain unacceptably high concentrations of pathogens. The assumption that slip number is an adequate predictor of pathogen concentrations is generally viewed as grossly oversimplified, but it has served as a practical solution absent more sophisticated methods of prediction. One of the goals of this project was generation of mathematic models which might enhance the ability of managers to assess probable pathogen loading around marinas. The models basically estimate dispersion of fecal coliforms (used as an indicator of pathogen levels) based on circulation patterns. Model output is clearly dependent on the initial loading assumption. This number is extremely difficult to estimate with any accuracy. In 1985, the United States Environmental Protection Agency developed a Coastal Marinas Assessment Han.dbook. The purpose of the handbook was to provide guidance in the design and 3 evaluation of marina projects. As part of that undertaking, the EPA contractor conducted an extensive review of available information in an effort to determine the fecal coliform loading attributable to each boat in a marina. The handbook referenced work done by Carstea et al. 197 5 in identifying the assumptions necessary to develop an estimate. These assumptions include: - average persons per boat is three; - average per capita discharges of coliform bacteria and BOD are 2 billion and 75.6 g respectively; - half of the people on board contribute fecal material in 24 hours; - coliform bacteria populations do not increase; - a boat in use spends one hour in the marina; - 25 to 40 percent of boats present are in use and evenly distributed. The difficulties associated with use of a number based on all these assumptions is self-evident The estimation of fecal coliform loading per boat in a marina is further complicated by the increased use of on-board marine sanitation devices. An even greater uncertainty derives from the potential influx of fecal coliforms from non-point sources. Schima et al. 1994 investigated the relationships between fecal coliform levels at 2,614 sampling stations and their landscape positions. They found a basic pattern of increasing fecal colifonn bacteria densities with distance upstream in tidal creeks and inlets. They refered to this as a "land mass" effect, or simply the amount of land within a fixed radius of sample locations. Regression analysis of the MPN concentrations at sampling points along the Eastern Shore of Virginia indicated the following variables (in order of decreasing importance) were significant in explaining changes in the sampled MPNvalues: - swface area of water in a 400 m raduius around the sampling point - season - tide stage during sampling - rainfall amounts in the 2 days prior to sampling - surface area of urban land in a 400 m radius around the sampling point 4 - near shore groundwater hydraulic gradient - slinity - proximity to nearest shoreline - near shore soil permeability - near shore runoff events - surface area of agricultural land in a 400 m radius around the sampling point - near shore Darcy velocity - water temperature One conclusion to be drawn from all of this is that while fecal coliform inputs from nonpoint sources on land may be very important, they are also very variable and difficult to predict, even on the basis of land use. 5 LANDUSE residential commercial TABLE 1 LOADING RATES BY LAND USE (kg/ha/yr) TSS 420 11-487 360-390 620-2,300 840 957 360 50-830 BOD COLIFORM 35 30-50 25,621-82,500(mpn/g) 87 36,900(mpn/g) agriculture mean 450 18 range 180-4,200 4-31 pasture mean 343 11.5 range 10-840 6-17 forest mean 85 5 range 15-132 2-7 6 SOURCE Wanielista, 1978 Bannerman et al., 1984 Marsalek, 1978 Sonzogni, 1980 Loehr, 1974 Ellis, 1986 W anielista, 1978 Bannerman et al., 1984 Maralek, 1978 Sonzogni, 1980 Ellis, 1986 Wanielista, 1978 Wanielista, 1978 Wanielista, 1978 LANDUSE residential commercial pasture agriculture TABLE 1 ( continued) LOADING RATES BY LANDUSE (kg/ha/yr) TN 5.0-7.3 9-11.2 5.4-18.0 6.6 1.9-11 11.2 16.3 14.5 mean 6.2 range 2.0-12.0 4.94 8.89 mean 26.0 range 15.0-37.0 TP 1.6-3.4 1.00-2.47 1.8 1.2-8.0 3.4 2.22 2.7 0.5 0.1-2.1 0.74 0.34-0.56 2.22 1.05 0.18-1.62 1.68-5.6 0.06-2.9 7 SOURCE Sonzogni, 1980 Marsalek, 1978 EPA, 1983 Wanielista, 1978 Whipple et al., 1978 Sonzogni, 1980 Marsalek, 1978 EPA, 1983 Wanielista, 1978 Wanielista, 1978 Beulac & Reckhow, 1982 Mackieman, 1985 Beulac & Reckhow, 1982 Wanielista, 1978 Mackieman, 1985 Loehr, 1974 TABLE 1 (continued) LOADING RATES BY LANDUSE (kg/ha/yr) LANDUSE TN TP SOURCE forest mean 3.0 0.10 Wanielista, 1978 range 2.0-5.1 0.01-0.86 2.47 0.25 Beulac & Reckhow, 1982 0.06-0.11 Mackiernan, 1985 0.03-0.9 Loehr, 1974 8 POLLUTANT TSS BOD COLIFORM TABLE2 STORM WATER RUNOFF ESTIMATES (mg/I) urban Durham,NC mean range agricultural watershed cultivated pasture urban area Cincinnati, OH mean range agricultural watershed Washington, DC Durham, NC mean 141-224 1,401-2,909 227 1,440 194-8,620 90-5,000 180-6,000 1,021 38 12-160 17 19 2-84 7 5-30 3-15 1,000-21,000 MPN/lOOml > 2,000 MPN/lOOml 76,100 23,000 range 100-200,000 9 SOURCE EPA, 1983 Wanielista, 1978 Carstea et al., 1975 Colston, 1974 Dornbush et al., 1974 Loehr, 1974 Carstea et al., 197 5 Weibel et al., 1964 Loehr, 1974 Dornbush et al., 1974 EPA, 1983 Olivieri et al,. 1977 Wanielista, 1978 Colston, 1974 TABLE 2 (continued) STORM WATER RUNOFF ESTIMATES (mg/I) POLLUTANT SOURCE COD Durham, NC mean 170 Colston, 197 4 range 20-1042 Cincinatti, OH mean 99 Weibel et al., 1964 range 20-610 agricultural 50-360 Dombush et al., 1974 watershed 70-780 pasture 49 TN 5.6-7.1 EPA, 1983 urban area mean 3.1 Weibel et al., 1966 range 0.3-75 3.1 Carstea et al., 1975 forested 0.3-1.8 Loehr, 1974 agriculture 9.0 Loehr, 1974 TP 0.4-0.5 EPA, 1983 agriculture 0.04-2.4 Dombrush et al., 1974 forested 0.01-0.11 Loehr, 1974 agriculture 0.02-1.7 Loehr, 1974 urban area 0.2-1.1 Loehr, 1974 1.1 Carstea et al., 1975 10 REFERENCES Bannerman, R., K. Baun, M. bohm. P.E. Hughes and D.A. Graczyk. 1984. Evaluation of Urban Nonpoint Source Pollution Management in Milwaukee County, Wisconsin. Report No. PB84-114 l 64. Chicago, Ill. EPA Region V. Beulac, M.N. and K.H. Reckhow. 1982. An examination oflanduse nutrient export relationships. Water Resources Bulletin. 18:1013-1023. Carstea, D., A. Binder, R. Strieter, L. Boberschmidt, L. Thomas and J. Golden. 1975. Guidelines for the environmental impact assessment of small structures and related activities in coastal bodies of water. Prepared by MITRE Corporation forU. S. Army Corps of Engineers, New York District. Clesceri, N.L. S.J. Curran, and R.I. Sedlak. 1986. Nutrient Loads to Wisconsin Lakes: Part I: Nitrogen and Phosphorus export coefficients. Water Res. Bull. 22(6):983-1000. Colston, N.V. Jr. Characterization and treatment of urban land runoff. Environ. Protection Technol. Series. EPA 670/2-74-096. 197 4. D'Elia, F. 1987. Nutrient Enrichment of the Chesapeake Bay: Too much of a good thing? Env. 29:6-33. Dombush, J.N., J.R. Anderson, L.L. Hanns. 1974. Quantification of pollutants in agricultural runoff. EPA-660/2-74-005. US EPA. Washington, D.C. Ellis, J.B. 1986. Pollutional aspects of urban runoff. pp.1-38 in H.C. Toma, J. Marsalek, and M.Desbordes, ma... Urban Runoff Pollution. Springer-Verlag, NY, Inc. 11 Loehr, R.C. 1974. Characteristics and comparative magnitude of non-point sources. Journal WPCF 46(8): 1849-1872. Mackiernan, G.B., D.A. Flemer, Nehlsen, W. V.K. Tippie and R.B. Biggs. 1985. Chesapeake Bay: A profile of environmental change. EPA, Annapolis, MD. Chesapeake Bay Program. Marsalek, J. 1978. Pollution Due to Urban Runoff: Unit Loads and Abatement Measures. Windsor, Canada: Pollution by Land Use Activities Reference Group of the International Joint Commission. Nagnien, R.E., R.M. Summers and K.G. Sellner. 1992. External Nutrient Sources, Internal Nutrient Pools, and Phytoplankton Production in Chesapeake Bay. Estuaries 15(4):497-516. Olivieri, V., C. Kruse, K. Kawata, and J. Smith. 1977. Microorganisms in Urban Stormwater. Report No. EPA 600/2-77-087. Cincinnati, OH: EPA Municipal Environmental Research Laboratory. Overton, D.E. and M.E. Meadows. 1976. Stormwater Modeling. NY Academic Press. Rast, W. and G.F. Lee. 1983. Nutrient Loading Estimates for Lakes. J.Env. Engineering. ASCE 109(2):502-517. Schima, F.J., W.G. Reay, D.L. Gallagher, G. M. Simmons, Jr., J.L. Waldon and K.K. Reay. 1994. Groundwater transport of fecal coliform bacteria to open coastal waters of Virginia's coastal plain: A GIS approach. Final Report to Virginia's Coastal Resource Sonzogni, W.C. 1980. Pollution from land runoff. Environ. Sci. and Tech. 14:148-153. 12 United States Environmental Protection Agency. 1985. Coastal Marina Assessment Handbook. USEP A 904/6-85-132. Region 4, Atlanta, Georgia. United States Environmental Protection Agency. 1983. Results of the Nationwide Urban Runoff Program: Volume 1. USEPA, Washington, D.C. Uttormark, P.D., J.D. Chapin and K.M. Green. 1974. Estimating Nutrient Loading of Lakes from non-point sources. US EPA 600/3-74-020. US EPA. Corvallis, OR. Wanielista, M.P. 1978 Stormwater Management: Quantity and Quality. Ann Arbor Science Publishers. Weibel, S.R. et al. 1964. Urban land runoff as a factor in stream pollution. J. WPCF. 36(7):914-924. Weibel, S.R. et al. 1966. Pesticides and Other Contaminants from Raingall and Runoff as Observed in Ohio. Jour. Amer. Water Works Assn. 58:1075-1084. Whipple, W. Jr. J.V. Hunter, and S.L. Yu. 1978. Runoff pollution from multiple family housing. Water Res. Bull. 14:288-301. 13 

Modeling cumulative impacts and the carrying capacity of small tidal creeks and inlets

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Modeling cumulative impacts and the carrying capacity of small tidal creeks and inlets

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