Biological Opinions - Bureau of Reclamation

Table 4.3. UKL fill rate adjustment factor.
Fill_rate_diff (ft/day) Fill_rate_adjust_wet Fill_rate_adjust_dry
< -0.02 0.6 0.2
0 1.0 1.0
> 0.03 1.4 1.0
“Fill_rate_diff” is the difference between the recent fill rate of UKL and the average fill rate
needed to reach 4,142.80 ft (1,262.73 m) on March 1. Positive values indicate recent fill rates
exceed the average rate needed to reach 4,142.80 ft (1,262.73 m) on March 1. Negative values
indicate recent fill rates are less than the average rate needed to reach 4,142.80 ft (1,262.73 m)
on March 1.
The “wet” and “dry” modifiers to the fill rate adjustment term are defined by the UKL
cumulative inflow index. The UKL cumulative inflow index (Upper Klamath
Lake_cum_inf_ind) is not calculated by the model, but instead is part of the model input
dataset. Because the model does not calculate the index, it must be calculated on a daily basis
during real-time operations over the life of the proposed action, as follows:
Upper Klamath Lake Index =
The day t-1 term indicates the value on the previous day. The index is then normalized between
0 and 1. Drier hydrologic conditions are defined as a value of the UKL cumulative inflow
index less than 0.30. An index value greater than 0.30 indicates any condition not defined as
dry but does not distinguish between average or wet conditions.
4.2.3.1.3 Net Accretion Adjustment
Releases from IGD can be greatly affected by the accretions between Link River Dam and IGD.
Low net accretions may result in the need to release more water from Link River Dam to
produce calculated IGD flows. High net accretions may result in less water being released from
Link River Dam to meet calculated IGD flows. The accretion adjustment modifies Link River
Dam releases in all hydrologic conditions between October 1 and November 15. Therefore,
higher releases at Link River Dam may offset low seasonal accretions downstream. Although
values are included in Table 4.4 for all conditions, the accretion adjustment is applied after
November 15 only in relatively dry conditions (defined by an UKL cumulative inflow index
value less than 0.30), when accretions below Link River dam are low and the accretion
adjustment is necessary to meet calculated IGD flows. Accretion adjustment multipliers are
presented in Table 4.4. As with other adjustment factors, intermediate multiplier values are
obtained by linear interpolation.
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