verification purposes. Also, the 

 USGS will compare its loading data 

 with historical data to note any 

 trends in loadings to the bay from 

 the major tributaries. An interim 

 data report of the USGS effort is now 

 available (Lang and Grason 1980) . 



POINT SOURCE INVENTORY 



The bay program will make esti- 

 mates of municipal and industrial 

 point source loadings from existing 

 EPA and state agency files. Mason 

 and McFadden (1980) reported that the 

 EPA Waste Water Systems Inventory 

 Survey is the best available data 

 base for municipal point source dis- 

 charges. This survey provides treat- 

 ment plant flows for the present and 

 projected design flows of municipal 

 plants. Information is available for 

 1978 (actual) and year 2000 (pro- 

 jected) effluent concentrations of 

 phosphorus, ammonia, total Kjeldahl 

 nitrogen, and total nitrogen for all 

 municipal point sources in the Chesa- 

 peake Bay basin with flows in excess 

 of one million gallons per day. The 

 most up-to-date and accurate informa- 

 tion will be utilized during model 

 calibration and verification and for 

 all model production runs. 



INTENSIVE WATERSHED STUDIES 



A set of intensive watershed 

 studies is being conducted to char- 

 acterize runoff pollution loadings 

 and to facilitate projections of non- 

 point source loads in the Chesapeake 

 Bay basin. The approach is to iso- 

 late small study sites which exhibit 

 relatively homogeneous land use, 

 geology, soils, topography, land 

 surface maintenance practices, etc. 

 These factors and others are being 

 related to the nonpoint source load- 



ing regime observed during monitor- 

 ing periods to characterize runoff 

 water quality by quantifiable land 

 and land use parameters. The tech- 

 nique of intensive monitoring of 

 small watersheds was chosen because 

 it represents the state of the art 

 of runoff pollution assessment. The 

 intensive watershed studies are in- 

 tended to identify the specific 

 sources of runoff pollution loads and 

 also to identify some of the physical 

 characteristics that determine the 

 responses of each source to hydro- 

 meteorologic inputs. When the data 

 are linked with appropriate water 

 quality assessment tools, they will 

 allow an assessment of the water 

 quality impacts of present and fu- 

 ture land use changes and provide the 

 potential for the control of runoff 

 loadings through the application of 

 Best Management Practices (BMPs). 



Presently, nonpoint monitoring 

 programs have begun in the Occoquan 

 River (9 sites) and Ware River (4 

 sites) watersheds in Virginia and 

 the Pequea Creek basin (5 sites) in 

 Pennsylvania. Similar studies are 

 scheduled to begin this summer in 

 Maryland watersheds (14 sites). 

 Sites have been selected to represent 

 a variety of land uses (18 Agricul- 

 tural, 6 Forested, 6 Residential, 2 

 Mixed), soils, and geologic forma- 

 tions as well as various other para- 

 meters, e.g., slope. These sites are 

 being monitored during both base flow 

 and storm event conditions for a 

 variety of pollutant constituents. In 

 addition, the performances of several 

 nonpoint pollution control measures 

 are being evaluated. Measures of 

 various land, land-surface and cul- 

 tural parameters are being documented 

 on each site for use in later charac- 

 terization efforts to be made through 

 the use of a deterministic computer- 

 based hydrologic, water quality 

 model . 



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