in particular in the absence of a pumping constraint this model would predict that each producer would pump until the value of the marginal product of water or marginal benefit of pumping was equal to zero as the pumping constraint becomes more binding the value of the marginal product of water will increase the optimal choice of marginal benefit depends on the degree to which pumping must be constrained to meet the aggregate pumping target the lower the desired value of the target the higher the marginal benefit needed to achieve it as each producer must be constrained more