Modeling Gone too Far

We’ve talked about it in class and it was mentioned in this week’s readings but the use of models in policy making is becoming ever prevalent. Modeling technology is improving on multiple fronts. Models are growing in scale, becoming more complex and at the same time, easier to use. These are all great advances which are leading to new regulations across multiple fields. And these regulations are being made with greater certainty and confidence. But any principled modeler will tell you scale, complexity, and ease of use do not always mean more accurate prediction. You here it over and over again in the academic field, “A model is just a tool to aid us in regulation, it should not be taken as fact.” Sometimes this idea gets lost in translation, and regulatory agencies rely too much on models for decision making.

An example of this can be found in Long Lake located in Spokane, WA. Long Lake was known to have significant dissolved oxygen (DO) problems. This made for an unhealthy environment for many of this fish species which make the lake home. It was determined that Phosphorus (P) was the main culprit. A regional effort was made to reduce P entering the lake. This was done by banning detergents containing P, and by requiring new P removing technologies to be installed in all treatment plants along the Long Lake river system. To determine discharge limits for the treatment plants, a CE QUAL-W2 model was used. The regulators decided upon using 3.5 mg/L as the discharge limit with the model as their main evidence. I was part of a group that looked at testing the models sensitivity. What we found was the model showed little change when altering P loadings from the treatment plants. What this meant, is that according to the model, it almost didn’t matter what P loading was, DO always responded similarly. It is completely plausible that the regulations being implemented in the Long Lake system are considerably overbearing and costing treatment systems thousands to millions of dollars.

It should be noted that the current condition of the lake is also up for debate. Some believe it to be completely recovered, others believe it to still be in poor quality and think that further regulation is necessary. But that discussion is for another day.


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