2018-03-09_PERMIT FILE - M2017049 ‎(28)‎

• Permit No: M2017049
• IBM Index Class Name: PERMIT FILE
• Doc Date: 3/9/2018
• Doc Name Note: PART 3 OF 3
• Doc Name: Adequacy Review Response
• From: Transit Mix Concrete Co.
• To: DRMS
• Permit Index Doc Type: Application Materials
• Email Name: TC1
• Email Name: ERR
• Email Name: ECS
• Email Name: WHE
• Email Name: AME
• Email Name: PSH
• Media Type: D
• Archive: No

I I
9-Asmu*�1;
During the fall and winter months, surface water runoff is minimal and groundwater discharge to
Little Turkey Creek provides the primary source of creek surface water flow upgradient of the
West Fault. Total surface water and groundwater outflow during the baseflow period, over an
annual cycle, can be used to estimate the average annual "net" ground water recharge (total
recharge minus evapotranspiration)in the upper part of the Little Turkey Creek watershed west of
the West Fault, as described in Section 3.4 of the main report text. The total groundwater
discharge from the upper Little Turkey Creek watershed, not considering any evaporation or
evapotranspiration, is estimated to range from 0.6 to 0.7 CFS.
The annual "net" recharge rate (after evaporation and evapotranspiration losses) to support the
range of total groundwater discharge from the upper Little Turkey Creek watershed is equivalent
to between 1.26 and 1.47 in/yr, if this recharge was evenly distributed across the 6.48 sq. mi. of
the upper watershed. This net recharge represents 7 to 8% of the annual precipitation of
19 inches, and 28 to 33% of the average annual snow precipitation of 4.5 inches, well within the
typical ranges for high elevation watersheds in the western US.
The initial net recharge inputs to the model were based on values within the average 1 to
1.5 inches per year range and distributed based on topographic elevation. These input values
were adjusted during calibration of the model to match Little Turkey Creek baseflows at the
downgradient end of the upper Little Turkey Creek watershed (coincident with the West Fault
location). Potentiometric elevation data matches were also used as a secondary calibration target.
The calibrated distribution of net recharge input to the model is shown on Figure E-2.
River Recharge and Discharge
Recharge to groundwater also occurs from infiltration of surface water in Little Turkey Creek and
its tributaries in areas where the groundwater table (saturated groundwater conditions) is below
the surface water elevation. Conversely, discharge of groundwater to Little Turkey Creek and its
tributaries occurs where the groundwater table (saturated groundwater conditions) is at or above
the surface water elevation in the creeks.
The recharge/discharge relationship between groundwater and surface water was simulated in the
model by "river" boundary conditions along Little Turkey Creek and its major tributaries, as
shown in Figure E-3. These boundary conditions allow exchange of flow between groundwater
and surface water depending on head differentials and a conductivity factor of the river bed. The
conductivity factor was adjusted during calibration of the model to match Little Turkey Creek
baseflows at the downgradient end of the upper Little Turkey Creek watershed (coincident with
the West Fault location).
TRANSIT MIX-HITCH RACK RANCH
HYDROGEOLOGY AND IMPACT ANALYSIS
E-6