diff --git a/README.md b/README.md
index e505efb..273d5fa 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,6 @@
 [![Conda-Forge][conda-badge]][conda-link]
 [![GitHub Discussion][github-discussions-badge]][github-discussions-link]
 
-
 <!-- prettier-ignore-start -->
 [actions-badge]:            https://github.com/opera-adt/opera-utils/workflows/CI/badge.svg
 [actions-link]:             https://github.com/opera-adt/opera-utils/actions
diff --git a/environment.yml b/environment.yml
index 9c2c051..275224f 100644
--- a/environment.yml
+++ b/environment.yml
@@ -5,6 +5,6 @@ dependencies:
   - python>=3.9
   - pip>=21.3  # https://pip.pypa.io/en/stable/reference/build-system/pyproject-toml/#editable-installation
   - git  # for pip install, due to setuptools_scm
-  - gdal>=3.3
   - h5py>=1.10
   - shapely>=1.8
+  # - gdal>=3.3  # For now, gdal will be an optional dependency
diff --git a/src/opera_utils/_dates.py b/src/opera_utils/_dates.py
index ebb5057..d4ebb72 100644
--- a/src/opera_utils/_dates.py
+++ b/src/opera_utils/_dates.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import datetime
 import re
 from pathlib import Path
diff --git a/src/opera_utils/_io.py b/src/opera_utils/_io.py
index e93ceb3..e69de29 100644
--- a/src/opera_utils/_io.py
+++ b/src/opera_utils/_io.py
@@ -1,27 +0,0 @@
-from os import fspath
-
-from osgeo import gdal
-
-from ._types import Filename
-
-__all__ = [
-    "get_raster_gt",
-]
-
-
-def get_raster_gt(filename: Filename) -> list[float]:
-    """Get the geotransform from a file.
-
-    Parameters
-    ----------
-    filename : Filename
-        Path to the file to load.
-
-    Returns
-    -------
-    List[float]
-        6 floats representing a GDAL Geotransform.
-    """
-    ds = gdal.Open(fspath(filename))
-    gt = ds.GetGeoTransform()
-    return gt
diff --git a/src/opera_utils/bursts.py b/src/opera_utils/bursts.py
index 5926eda..02f64ba 100644
--- a/src/opera_utils/bursts.py
+++ b/src/opera_utils/bursts.py
@@ -6,13 +6,13 @@
 import re
 import subprocess
 import tempfile
+from os import fspath
 from pathlib import Path
 from typing import Iterable, Pattern, Sequence, Union, overload
 
 import h5py
 from shapely import geometry, ops, wkt
 
-from ._io import get_raster_gt
 from ._types import Filename, PathLikeT
 from .constants import OPERA_BURST_RE, OPERA_DATASET_NAME, OPERA_IDENTIFICATION
 
@@ -178,7 +178,7 @@ def make_nodata_mask(
     buffer_pixels: int = 0,
     overwrite: bool = False,
 ):
-    """Make a boolean raster mask from the union of nodata polygons.
+    """Make a boolean raster mask from the union of nodata polygons using GDAL.
 
     Parameters
     ----------
@@ -245,3 +245,23 @@ def make_nodata_mask(
         cmd = f"gdal_rasterize -q -burn 1 {temp_vector_file} {out_file}"
         logger.info(cmd)
         subprocess.check_call(cmd, shell=True)
+
+
+def get_raster_gt(filename: Filename) -> list[float]:
+    """Get the geotransform from a file.
+
+    Parameters
+    ----------
+    filename : Filename
+        Path to the file to load.
+
+    Returns
+    -------
+    List[float]
+        6 floats representing a GDAL Geotransform.
+    """
+    from osgeo import gdal
+
+    ds = gdal.Open(fspath(filename))
+    gt = ds.GetGeoTransform()
+    return gt
diff --git a/src/opera_utils/constants.py b/src/opera_utils/constants.py
index d9326f0..468baf7 100644
--- a/src/opera_utils/constants.py
+++ b/src/opera_utils/constants.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import re
 
 __all__ = [