There is a temporal variation in the proportion of the mean annual flow (MAF) to maintain different levels of fish-habitat conditions (Table 1). eij (m3) is EFR in month i at habitat quality level j, ni is the number of days in month i, Qi (m3/s) is the mean daily flow in month i (calculated by the APEX model), and Pij (%) is the percentage of the mean annual flow in month i at habitat quality levelj ( Table 1).