and accumulation of excess nutri- 

 ents), and (3) the decline of sub- 

 merged vegetation. Recently, dredg- 

 ing and spoil disposal were added as 

 a fourth technical area. There is 

 also a focus on management as a spe- 

 cial area of study. 



The program has a strong focus 

 on water quality which is inextric- 

 ably linked with freshwater supply. 

 The many important uses of the bay 

 including associated living resources 

 require that water quality and quan- 

 tity information be an integral part 

 of the research plan (U.S. EPA 

 1980). 



The quantity and timing of 

 freshwater inflow to the bay is known 

 to affect the circulation and distri- 

 bution of salinity in the bay's 

 waters. The salinity distribution 

 has a fundamental relationship to the 

 growth, reproduction and survival of 

 the biota and to the chemistry of the 

 bay's waters and sediments. Knowl- 

 edge about circulation is important 

 in specifying the distribution and 

 characterization of pollutants and 

 the resulting exposure of organisms 

 to toxic chemicals and nutrients. 



A conceptual program framework 

 is provided to assist in the tracking 

 of the numerous activities that range 

 from an analysis of loadings of toxic 

 chemicals and nutrients to the tidal 

 estuarine system to possible manage- 

 ment control alternatives (Figure 2) . 

 This paper emphasizes the modeling 

 approach, model components, analyti- 

 cal approach and problem assessment. 

 Beacuse of the state of the art and 

 the allocation of resources, more 

 emphasis is given to water quality 

 modeling of nutrients and their rela- 

 tionship to the dissolved oxygen 

 deficit than to toxic substances. 

 All work discussed in this paper was 

 undertaken with the intent of bay- 

 wide application. 



Work in the submerged aquatic 

 vegetation area is oriented with 

 emphasis on the distribution and 

 abundance of the grasses environment- 

 al factors, e.g., light requirements 

 and herbicide effects, ecological 

 processes, e.g., nutrient cycling and 

 value of the grasses as food and 

 habitat to fish and wildlife. This 

 work will not be discussed specif- 

 ically in this paper except in the 

 context of sources and transport and 

 fate of nutrients, sediments and 

 toxic chemicals within the bay sys- 

 tem. 



OBJECTIVES 



NUTRIENTS 



The objectives of the eutrophi- 

 cation program are: (1) To determine 

 the state of the bay with regard to 

 nutrient enrichment, past and pres- 

 ent, (2) to quantify the nutrient 

 levels in Chesapeake Bay based on 

 water quality standards, non-degrada- 

 tion and water quality enhancement 

 for years 1980 and 2000, and (3) to 

 evaluate nutrient control alterna- 

 tives for achieving and maintaining 

 acceptable nutrient levels in the 

 Chesapeake Bay at present (1980) and 

 in the future (2000). 



As referenced above, the second 

 objective of the eutrophication pro- 

 gram is to quantify nutrient loadings 

 to the Chesapeake Bay from various 

 sources. In order to achieve this 

 important objective, current research 

 is directed toward: (1) assessing 

 point source information on municipal 

 and industrial sources, (2) compiling 

 statistics on land use and population 

 trends in the bay basin, (3) measur- 

 ing nutrient loadings from the major 

 tributaries to the bay, (4) estimat- 

 ing nutrient fallout from the atmos- 

 phere, (5) verifying nonpoint source 



187 



