diff --git a/cstar/base/input_dataset.py b/cstar/base/input_dataset.py
index 7665efb..fb2229c 100644
--- a/cstar/base/input_dataset.py
+++ b/cstar/base/input_dataset.py
@@ -98,7 +98,7 @@ class InputDataset(ABC):
         The base model with which this input dataset is associated
     source: DataSource
         Describes the location and type of the source data
-    file_hash: str
+    file_hash: str, default None
         The 256 bit SHA sum associated with the file for verifying downloads
     exists_locally: bool, default None
         True if the input dataset exists on the local machine, set by `check_exists_locally()` method if source is a URL
@@ -117,7 +117,7 @@ def __init__(
         self,
         base_model: "BaseModel",
         source: DataSource,
-        file_hash: str,
+        file_hash: Optional[str] = None,
         start_date: Optional[str | dt.datetime] = None,
         end_date: Optional[str | dt.datetime] = None,
     ):
@@ -138,7 +138,14 @@ def __init__(
         self.base_model: "BaseModel" = base_model
 
         self.source: DataSource = source
-        self.file_hash: str = file_hash
+        self.file_hash: Optional[str] = file_hash
+
+        if (self.file_hash is None) and (self.source.location_type == "url"):
+            raise ValueError(
+                f"Cannot create InputDataset for \n {self.source.location}:\n "
+                + "InputDataset.file_hash cannot be None if InputDataset.source.location_type is 'url'.\n"
+                + "A file hash is required to verify files downloaded from remote sources."
+            )
 
         self.exists_locally: Optional[bool] = None
         self.local_path: Optional[str] = None
diff --git a/cstar/case.py b/cstar/case.py
index a4a0a54..52b7047 100644
--- a/cstar/case.py
+++ b/cstar/case.py
@@ -381,8 +381,8 @@ def from_blueprint(
                     model_grid = [
                         ROMSModelGrid(
                             base_model=base_model,
-                            source=DataSource(f["source"]),
-                            file_hash=f["hash"],
+                            source=DataSource(f.get("source")),
+                            file_hash=f.get("hash", None),
                         )
                         for f in input_dataset_info["model_grid"]["files"]
                     ]
@@ -397,10 +397,10 @@ def from_blueprint(
                     initial_conditions = [
                         ROMSInitialConditions(
                             base_model=base_model,
-                            source=DataSource(f["source"]),
-                            file_hash=f["hash"],
-                            start_date=f["start_date"],
-                            end_date=f["end_date"],
+                            source=DataSource(f.get("source")),
+                            file_hash=f.get("hash", None),
+                            start_date=f.get("start_date", None),
+                            end_date=f.get("end_date", None),
                         )
                         for f in input_dataset_info["initial_conditions"]["files"]
                     ]
@@ -417,8 +417,8 @@ def from_blueprint(
                     tidal_forcing = [
                         ROMSTidalForcing(
                             base_model=base_model,
-                            source=DataSource(f["source"]),
-                            file_hash=f["hash"],
+                            source=DataSource(f.get("source")),
+                            file_hash=f.get("hash", None),
                         )
                         for f in input_dataset_info["tidal_forcing"]["files"]
                     ]
@@ -435,10 +435,10 @@ def from_blueprint(
                     boundary_forcing = [
                         ROMSBoundaryForcing(
                             base_model=base_model,
-                            source=DataSource(f["source"]),
-                            file_hash=f["hash"],
-                            start_date=f["start_date"],
-                            end_date=f["end_date"],
+                            source=DataSource(f.get("source")),
+                            file_hash=f.get("hash", None),
+                            start_date=f.get("start_date", None),
+                            end_date=f.get("end_date", None),
                         )
                         for f in input_dataset_info["boundary_forcing"]["files"]
                     ]
@@ -455,10 +455,10 @@ def from_blueprint(
                     surface_forcing = [
                         ROMSSurfaceForcing(
                             base_model=base_model,
-                            source=DataSource(f["source"]),
-                            file_hash=f["hash"],
-                            start_date=f["start_date"],
-                            end_date=f["end_date"],
+                            source=DataSource(f.get("source")),
+                            file_hash=f.get("hash", None),
+                            start_date=f.get("start_date", None),
+                            end_date=f.get("end_date", None),
                         )
                         for f in input_dataset_info["surface_forcing"]["files"]
                     ]