Subsurface recharge is a surface water model (Topnet-WM) output that can be used as an independent constraint on the groundwater recharge that is specified for the groundwater model (MODFLOW). This will help to ensure that the surface water and groundwater models are internally consistent. The surface water modeling will help to identify a longterm period of representative climatic conditions and resulting groundwater recharge, which can serve as input over a representative time period and for the calibration of a steadystate groundwater model. The surface water modeling will also provide important insights about stream baseflows for calibrating the groundwater model. The analysis of surface water and groundwater conditions is conducted over a large model domain with progressively increasing resolution (e.g. with increased focus in Bertrand, Fishtrap, Kamm, Schneider, Wiser/Cougar, Scott, Fourmile, Tenmile and Deer Creek drainage areas) where we are addressing specific questions of drainage impacts and groundwater withdrawal impacts from wells on surface water. The current model domain of the surface water flow model, Topnet-WM, includes the entire WRIA 1 watershed, but calibration and water use inputs have only been refined for the Lower Nooksack Subbasin portion of the basin with additional model development was previously completed in the Bertrand Creek and Fishtrap Creek drainages resulting in the surface model resolution being increased from a single watershed average to 46 sub-drainages per watershed. The following steps estimate groundwater recharge in the conceptual/numerical groundwater model:
 A coarse distribution of recharge will be developed for the entire conceptual/numerical model domain (38 of 172 basins in WRIA1 within GW model domain). Model simulations for GW model test coupling with outputs for Water Management On and Off are in the compressed file <modelruns_1952_WRIA1_081418.gz>
 For the Lower Nooksack Subbasin, watershed-scale average groundwater recharge values developed by the 2012 Topnet-WM surface water model will be specified as initial inputs to the groundwater model.
 The greater resolution groundwater recharge estimates for Bertrand Creek sub-drainages developed from the 2016 Topnet-WM model are also used as input to the groundwater model .

Initial work:
 Jupyter Notebooks contain code that can be used to run the Topnet model with R code for processing outputs to develop Annual estimates of water budget quantities per drainage.
Resigned work:
The original Topnet-WM model written in Fortran was recoded in C++ and new model output files were designed for groundwater model coupling.