Shared Vision Planning


Boston Metropolitan Studies

The New England Division of the Corps of Engineers worked with the Massachusetts Water Resources Authority (MWRA) and the Water Supply Citizens Advisory Committee (WSCAC) on three projects: 

  • The development of trigger planning using a simulation model of the MWRA system built using STELLA II ®

  • Use of a beta version of IWR-MAIN 6.0 to determine the cost effectiveness of current and future demand management measures

  • A history of the MWRA, WSCAC, and other Massachusetts agencies. The purpose of the history is to develop a basis for recommending management solutions that have worked here for other areas in the U.S

For many years, MWRA and WSCAC have been concerned that the existing strategic planning framework does not provide sufficient flexibility to adequately assess a wide range of alternative solutions. Two primary shortcomings of the existing planning approach have been cited.

First, once adopted, MWRA’s strategic plans are typically not reviewed until the end of a specified planning period, often 15 to 20 years. This episodic approach does not allow the system to respond to changes in demand, regulatory requirements and social concerns that occur during the planning period. Because corrective actions are postponed, the options to address the problems that exist at the end of the planning period may be extremely limited.

A second criticism of existing strategic planning is that it is often divorced from tactical planning efforts. For example, the effectiveness of adopted drought management plans may not be considered when evaluating strategic alternatives.

Trigger Planning provides for continuous monitoring of indicators of future water supply conditions under existing management policy. Trigger planning identifies a mechanism for determining when a change in this strategy is needed. It also accounts for the impacts of existing tactical response plans in evaluating system performance from a strategic perspective. It should provide greater lead time to adequately scope and evaluate a wide range of potential alternatives, both strategic and tactical. 

Currently, five system performance measures have been incorporated into the model (Table 10). These measures were chosen as indicators of environmental quality, consumer impacts, and the quantity of water available. The performance measures were easily represented within the STELLA II® model. In contrast, it was much more difficult to establish consensus on which measures were most valuable.

Table 10:  Performance Measures for Strategic Trigger Planning in the Boston Area


Performance Criterion


Water Quantity


Number of times where supply is less than the unconstrained demand. Alternatively, the volume of such a water deficit.

Environmental Quality*


The maximum number of consecutive months Quabbin reservoir is below target pool.

Maximum Pool Descent

The elevation of the maximum deviation of Quabbin reservoir elevation from target pool.


A ratio expressed as a percentage of durations: the tolerable stay below target pool/particular stay below target pool.

Consumer Impacts

Drought Actions

The number of months at each drought restriction level.

* as Quabbin is drawn down, there is an impact on riparian areas and water quality within Quabbin for fish habitat. Deep draw downs reduce municipal water supply.

During the course of the study, the model has been used to examine the impact of drought management on system performance and to predict system performance for the year 2012 under four different demand scenarios. The model has also influenced the formulation of performance measures in the trigger planning framework. Had the model not been available, it is unlikely that the same measures would have been chosen. Furthermore it is unlikely that the implications of these measures would be as well understood. Study participants reported that their model-aided investigation of performance measures greatly enhanced their understanding of the trade-offs involved in system operation. It is likely that the model will continue to be used in the definition of the trigger planning framework. For example, it may help participants reach consensus on the points when these measures indicate an unacceptable level of system performance. Such discussions will likely lead to the refinement of the definitions used for critical points and will provide guidance for future assessment of alternatives within the trigger planning framework.

Although Corps involvement in the trigger planning effort ceased upon completion of the National Drought Study, much work remains. Both MWRA and WSCAC are confident that both the trigger planning paradigm and model content will continue to be refined, largely because of the success of the efforts so far. Likely activities include further enhancements to equation documentation and model clarity. Demonstrations of the trigger planning concept and the object oriented model to a larger audience within MWRA, WSCAC and the Corps, and other interested agencies will occur. 

Water demand management software (IWR-MAIN) will be brought on line to improve the quality of the demand forecasts required of the trigger planning process. Trigger planning will begin to be integrated into future planning documents and is anticipated to become the accepted agency planning approach. The existing model will be used annually to perform the trigger planning analyses. As trigger points are approached, the model will be adapted to analyze a wide range of potential alternatives. WSCAC has also expressed an interest in using this model to reevaluate the adequacy of the triggering mechanisms in MWRA’s existing drought response plan.