diff --git a/route/build/src/dfw_route.f90 b/route/build/src/dfw_route.f90
index 2781d66b..1be0b4af 100644
--- a/route/build/src/dfw_route.f90
+++ b/route/build/src/dfw_route.f90
@@ -76,12 +76,13 @@ SUBROUTINE dfw_rch(this,           & ! dfw_route_rch object to bound this proced
  end if
 
  ! get discharge coming from upstream
- nUps = size(NETOPO_in(segIndex)%UREACHI)
+ nUps = count(NETOPO_in(segIndex)%goodBas) ! reminder: goodBas is reach with >0 total contributory area
  isHW = .true.
  q_upstream = 0.0_dp
  if (nUps>0) then
    isHW = .false.
    do iUps = 1,nUps
+     if (.not. NETOPO_in(segIndex)%goodBas(iUps)) cycle ! skip upstream reach which does not any flow due to zero total contributory areas
      iRch_ups = NETOPO_in(segIndex)%UREACHI(iUps)      !  index of upstream of segIndex-th reach
      if (qmodOption==1 .and. RCHFLX_out(iens,iRch_ups)%Qobs/=realMissing) then
        RCHFLX_out(iens, iRch_ups)%ROUTE(idxDW)%REACH_Q = RCHFLX_out(iens,iRch_ups)%Qobs
diff --git a/route/build/src/kwe_route.f90 b/route/build/src/kwe_route.f90
index efb0f224..b431b27a 100644
--- a/route/build/src/kwe_route.f90
+++ b/route/build/src/kwe_route.f90
@@ -77,12 +77,13 @@ SUBROUTINE kw_rch(this,           & ! kwe_route_rch object to bound this procedu
  end if
 
  ! get discharge coming from upstream
- nUps = size(NETOPO_in(segIndex)%UREACHI)
+ nUps = count(NETOPO_in(segIndex)%goodBas) ! reminder: goodBas is reach with >0 total contributory area
  isHW = .true.
  q_upstream = 0.0_dp
  if (nUps>0) then
    isHW = .false.
    do iUps = 1,nUps
+     if (.not. NETOPO_in(segIndex)%goodBas(iUps)) cycle ! skip upstream reach which does not any flow due to zero total contributory areas
      iRch_ups = NETOPO_in(segIndex)%UREACHI(iUps)      !  index of upstream of segIndex-th reach
      if (qmodOption==1 .and. RCHFLX_out(iens,iRch_ups)%Qobs/=realMissing) then
        RCHFLX_out(iens, iRch_ups)%ROUTE(idxKW)%REACH_Q = RCHFLX_out(iens,iRch_ups)%Qobs
diff --git a/route/build/src/mc_route.f90 b/route/build/src/mc_route.f90
index a421b916..eac4164a 100644
--- a/route/build/src/mc_route.f90
+++ b/route/build/src/mc_route.f90
@@ -76,12 +76,13 @@ SUBROUTINE mc_rch(this,           & ! mc_route_rch object to bound this procedur
  end if
 
  ! get discharge coming from upstream
- nUps = size(NETOPO_in(segIndex)%UREACHI)
+ nUps = count(NETOPO_in(segIndex)%goodBas) ! reminder: goodBas is reach with >0 total contributory area
  isHW = .true.
  q_upstream = 0.0_dp
  if (nUps>0) then
    isHW = .false.
    do iUps = 1,nUps
+     if (.not. NETOPO_in(segIndex)%goodBas(iUps)) cycle ! skip upstream reach which does not any flow due to zero total contributory areas
      iRch_ups = NETOPO_in(segIndex)%UREACHI(iUps)      !  index of upstream of segIndex-th reach
      if (qmodOption==1 .and. RCHFLX_out(iens,iRch_ups)%Qobs/=realMissing) then
        RCHFLX_out(iens, iRch_ups)%ROUTE(idxMC)%REACH_Q = RCHFLX_out(iens,iRch_ups)%Qobs