diff --git a/echopype/commongrid/api.py b/echopype/commongrid/api.py
index 8ea4cfc21e..6394018b88 100644
--- a/echopype/commongrid/api.py
+++ b/echopype/commongrid/api.py
@@ -9,12 +9,6 @@
 
 from ..utils.prov import add_processing_level, echopype_prov_attrs, insert_input_processing_level
 from .mvbs import get_MVBS_along_channels
-from .nasc import (
-    check_identical_depth,
-    get_depth_bin_info,
-    get_dist_bin_info,
-    get_distance_from_latlon,
-)
 
 
 def _set_var_attrs(da, long_name, units, round_digits, standard_name=None):
@@ -310,7 +304,7 @@ def compute_MVBS_index_binning(ds_Sv, range_sample_num=100, ping_num=100):
 #     bin_num_dist, dist_bin_idx = get_dist_bin_info(dist_nmi, cell_dist)  # dist_bin_idx is 1-based
 
 #     # Find binning indices along depth: channel-dependent
-#     bin_num_depth, depth_bin_idx = get_depth_bin_info(ds_Sv, cell_depth)  # depth_bin_idx is 1-based
+#     bin_num_depth, depth_bin_idx = get_depth_bin_info(ds_Sv, cell_depth)  # depth_bin_idx is 1-based  # noqa
 
 #     # Compute mean sv (volume backscattering coefficient, linear scale)
 #     # This is essentially to compute MVBS over a the cell defined here,