diff --git a/src/conceptual_reservoir.c b/src/conceptual_reservoir.c
index 496429c..d342471 100644
--- a/src/conceptual_reservoir.c
+++ b/src/conceptual_reservoir.c
@@ -46,6 +46,11 @@ extern void conceptual_reservoir_flux_calc(struct conceptual_reservoir *da_reser
     
     *primary_flux_m = da_reservoir->coeff_primary * (exp_term - 1.0);
     *secondary_flux_m = 0.0;
+
+    // cap so flux never exceeds storage
+    if (*primary_flux_m > da_reservoir->storage_m) {
+        *primary_flux_m = da_reservoir->storage_m;
+    }
     
     return;
   }