A.W. Research Laboratories, Inc.

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Mass Balance Analysis

A mass balance analysis in very similar to “balancing the checkbook of your bank account”.  Just as when you carefully record all deposits and withdrawals to track how much money you have in your account, the goal of a mass balance is the monitor the inflow and outflow of aquatic nutrients and sediment in your watershed.  A mass balance analysis monitors all major tributaries, which allows lake managers to evaluate whether a lake is currently acting as a “sink” for nutrients and sediment, or whether it is passing them downstream via its outlets.

 

A typical mass balance program utilizes volunteers from the sponsoring lake association, watershed district, or resource management agency to measure flow on all major inlets and outlets every two weeks.  In addition, water samples are collected monthly at each sample site, or more often in the spring and during storm events which can radically change watershed dynamics.

 

Upon completion of the data collection and analysis, the sponsor receives an interpretive report and series of spread sheets and graphs which compare the relative contribution of each inlet or outlet, as well as an overall summary of the watershed—wide mass balance of flow, nutrients, and total suspended solids.  This information is valuable in developing priorities for mitigations or educational efforts, for estimating spread of recovery of a lake undergoing restoration efforts, and for demonstrating the influence of land management within the watershed.

Example

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