Thomas M. Heidtke

Modeling fecal coliform bacteria—II. Model development and application

Abstract The episodic nature of their origin and the transience of the receiving water response make the modeling of fecal coliform bacteria contamination events particularly challenging. A two-layer mass balance model was developed to simulate spatial and temporal variability in fecal coliform bacteria concentrations in a polluted, urban lake. Independently validated submodels were used to estimate bacteria loads from tributary and point source discharges, to quantify mass transport and to determine losses due to sedimentation and death. The overall model was validated by successfully simulating spatial and temporal dynamics for dry weather conditions and two wet weather events. Sensitivity analyses indicate that the likelihood of violating public health standards is influenced by environmental conditions, e.g. light intensity and wind mixing. Model simulations are used to illustrate the impact of water quality management actions on bacteria levels at various locations in the lake. The general approach presented here and the techniques used to quantify model inputs may be of value in application to other systems.

Chloride model for polluted onondaga lake

Abstract The validation of a mass balance chloride (Cl) model for enriched Onondaga Lake is documented for the period 1973–1991. The history of loading of Cl to the lake, extending from the mining of NaCl brines adjoining the lake in the late 1700s, through the 102 year period of operation and discharges of an adjoining soda ash/chlor-alkali facility, is reviewed. Loads are estimated for the 1973–1991 interval based on a program of continuous flow measurements and bi-weekly monitoring of Cl concentration for the major inflows. The model performs well in matching the substantial seasonal variations in lake Cl concentration and the major reduction in concentration observed since closure of the facility in 1986 (from about 1585 to 430 mg l −1 ). Projections with the validated model demonstrate the Cl concentration in the lake would be about 230 mg l −1 , nearly 50% lower than the present concentration, without the continuing waste input from the soda ash/chlor-alkali facility.

Implementing Ecosystem-basedManagement: Lessons from the Great Lakes

Under the US-Canada Great Lakes Water Quality Agreement, a Remedial Action Plan (RAP) Program was formalized to identify and implement actions needed to restore beneficial uses in the most polluted areas of the Great Lakes (i.e. Areas of Concern). It was further required that individual RAPs embody a systematic and comprehensive ecosystem approach (i.e. an approach which accounts for interrelationships among land, air, water and all living things, including humans, and involves user groups in comprehensive management). Careful review and analysis of the RAP Program offers an opportunity to gain a better understanding of ecosystem-based management for other watersheds, and to identify important principles and elements which contribute to effective implementation. Principles which are considered essential for effective implementation of ecosystem-based management include: (1) broad-based stakeholder involvement; (2) commitment of top leaders; (3) agreement on information needs and interpretation; (4) action planning within a strategic framework; (5) human resource development; (6) results and indicators to measure progress; (7) systematic review and feedback; and (8) stakeholder satisfaction. The Great Lakes RAP experience with ecosystem-based management also demonstrates the need for a transition from a traditional,command-and-control,regulatory approach of governmentalagencies toward a more co-operative,value-added,support-basedrole. Review of RAPs in all 42 Areas of Concern provides compelling evidence that successful application of ecosystem-based management is dependent on broad-based stakeholder involvement in decision making, along with strong partnerships which encourage collaboration, co-operation and adaptability in management actions.

Mechanistic Modeling of Water Quality in Onondaga Lake

Water quality modeling serves two important, and at times disparate, purposes: (1) to support basic research, by providing a quantitative framework for the synthesis of scientific data, and (2) to support effective management of water resources by providing reliable predictive frameworks. These research and management purposes are mutually consistent on a long-term basis, as research advancements have led to improved capabilities and credibility of mechanistic management models (Chapra and Reckhow 1983; Thoman and Mueller 1987). Empirical modeling (e.g., Reckhow and Chapra 1983) can be valuable in certain instances, but is often inadequate for more complex water quality problems. Further it provides only very limited theoretical insight. Models developed for Onondaga Lake and the adjoining Seneca River, as documented here, are mechanistic, as they explicitly accommodate key mechanisms underlying the dynamics of various aspects of the water quality of these systems. Model testing, to establish the credibility of each model, and application for selected management scenarios are also documented in this chapter. The models presented here are intended to meet both the research and management purposes stated above. The models will serve to identify and test hypotheses for ongoing research and guide related programs. They will undoubtedly evolve as research on the lake continues. In the shorter term, the models are expected to support management decisions related to the reclamation of this highly polluted lake and the protection of the adjoining river system.