LAKE Negative value of the lake number of the lake where the gage is located.

•The Gage Package can also be used in conjunction with the Stream Flow Routing (SFR) Package to specify the location of a gaging station on a stream. Therefore, to guarantee that the code can distinguish between input for lakes and that for stream locations, lake numbers are specified as their negative value.

UNIT Unit number for output file. Specify negative value of unit number to invoke reading of optional parameter OUTTYPE for listing additional information for lakes.

•The user should specify a unique unit number for each gaging station and match those unit numbers to DATA file types and file names in the MODFLOW name file (Harbaugh and McDonald, 1996b).

OUTTYPE Code for type of expanded listing desired in output file:

0.Use standard default listing of time, stage, volume, and concentration.

1.

2.

3.All of the above except time-step budget error.

4.Time, lake stage, lake volume, solute concentration, and rate of change of lake volume, as well as volumetric rates for all inflows to and outflows from lakes (L3/T), total lake conductance (L2/T), and time-step budget error. Volumetric rates of computed runoff from UZF and lake infiltration to UZF is added whenever the UZF Package is active in MODFLOW-2005, MODFLOW-CFP, MODFLOW-NWT, and MODFLOW-LGR.

Total lake conductance (OUTTYPE options 1 and 3 for a lake gaging station) is the sum of the conductances of each seepage interface for each lake. Changes in lake stage, volume, and solute concentrations (OUTTYPE options 2 or 3) are listed as incremental changes from previous time increment and as cumulative change since start of simulation.Volumetric rates for option 4 are expressed in units of volume per time during a time step increment. Versions of the GAGE Package since 2006 for MODFLOW-2000 and MODFLOW-2005 had listed groundwater inflows and outflows as volumetric flow rates and listed the other values as volumes per time step for options 1 and 3.

GAGESEG An integer value that is the stream segment number where gage is located.

GAGERCH An integer value that is the stream reach number where gage is located.

UNIT An integer value that is the unit number of output file for this gage.

OUTTYPE An integer value that is a flag for type of expanded listing desired in output file:

•0 Use standard default listing of time, stage, outflow, and solute concentration.

•1 Default values plus depth, width, and flow at midpoint.

•2 Default values plus streambed conductance for the reach, head difference across streambed, and hydraulic gradient across streambed.

•3 Default values plus solute load in stream (if GWT is active).

•4 All of the above.

•5 Use for diversions to provide a listing of time, stage, flow diverted, maximum assigned diversion rate, flow at end of upstream segment prior to diversion, solute concentration, and solute load.

•6 Used for unsaturated flow routing to provide a listing of time, stage, groundwater head, streambed seepage, change in unsaturated storage, and recharge.

•7 Used for unsaturated flow routing to provide a listing of time and the unsaturated water content profile beneath the stream. Two profiles are printed. The first is the volume average water content of ISUZN unsaturated cells beneath a stream reach. The second profile is the volume averaged water content beneath the low flow channel only. If ISUZN =1 then both water content profiles will be the same.

•8 Use for unsaturated flow to provide a listing of time and the following budget components summed over all stream reaches: stream loss; stream gain; infiltration into the unsaturated zone; change of storage in the unsaturated zone; recharge; and storage in the unsaturated zone.