diff --git a/api/observation.py b/api/observation.py
index f4fa65ec4..51b100ebe 100644
--- a/api/observation.py
+++ b/api/observation.py
@@ -30,12 +30,9 @@
     GroundwaterLevelObservationResponse,
     CreateWaterChemistryObservation,
     WaterChemistryObservationResponse,
-    # CreateGeothermalObservation,
-    # GeothermalObservationResponse,
     ObservationResponse,
     UpdateGroundwaterLevelObservation,
     UpdateWaterChemistryObservation,
-    # UpdateGeothermalObservation,
 )
 from services.crud_helper import model_deleter, model_adder
 from services.query_helper import simple_get_by_id
@@ -81,19 +78,6 @@ async def add_water_chemistry_observation(
     return model_adder(session, Observation, obs_data, user=user)
 
 
-# @router.post("/geothermal", status_code=HTTP_201_CREATED)
-# async def add_geothermal_observation(
-#     obs_data: CreateGeothermalObservation,
-#     session: session_dependency,
-#     user: admin_dependency,
-# ) -> GeothermalObservationResponse:
-#     """
-#     Add a new geothermal observation to the database.
-#     This endpoint is currently a placeholder and does not implement any functionality.
-#     """
-#     return model_adder(session, Observation, obs_data, user=user)
-
-
 # PATCH ========================================================================
 
 
@@ -125,20 +109,6 @@ async def update_water_chemistry_observation(
     return observation_model_patcher(session, request, observation_id, obs_data, user)
 
 
-# @router.patch("/geothermal/{observation_id}", status_code=HTTP_200_OK)
-# async def update_geothermal_observation(
-#     observation_id: int,
-#     obs_data: UpdateGeothermalObservation,
-#     session: session_dependency,
-#     user: admin_dependency,
-#     request: Request,
-# ) -> GeothermalObservationResponse:
-#     """
-#     Update an existing geothermal observation in the database.
-#     """
-#     return observation_model_patcher(session, request, observation_id, obs_data, user)
-
-
 # ============= Get ==============================================
 
 
@@ -237,49 +207,6 @@ async def get_water_chemistry_observation_by_id(
     )
 
 
-# @router.get("/geothermal", summary="Get geothermal observations")
-# async def get_geothermal_observations(
-#     request: Request,
-#     session: session_dependency,
-#     user: viewer_dependency,
-#     thing_id: int | None = None,
-#     sensor_id: int | None = None,
-#     sample_id: int | None = None,
-#     start_time: datetime | None = None,
-#     end_time: datetime | None = None,
-#     sort: str | None = None,
-#     order: str | None = None,
-#     filter_: str = Query(alias="filter", default=None),
-# ) -> CustomPage[GeothermalObservationResponse]:
-#     """
-#     Retrieve all geothermal observations from the database.
-#     """
-#     return get_observations(
-#         request=request,
-#         session=session,
-#         thing_id=thing_id,
-#         sensor_id=sensor_id,
-#         sample_id=sample_id,
-#         start_time=start_time,
-#         end_time=end_time,
-#         sort=sort,
-#         order=order,
-#         filter_=filter_,
-#     )
-
-
-# @router.get("/geothermal/{observation_id}", summary="Get geothermal observation by ID")
-# async def get_geothermal_observation_by_id(
-#     session: session_dependency,
-#     request: Request,
-#     user: amp_viewer_dependency,
-#     observation_id: int,
-# ) -> GeothermalObservationResponse:
-#     return get_observation_of_an_activity_type_by_id(
-#         session=session, request=request, observation_id=observation_id
-#     )
-
-
 @router.get("", summary="Get all observations")
 async def get_all_observations(
     request: Request,
diff --git a/core/lexicon.json b/core/lexicon.json
index d78b1281c..17f27765e 100644
--- a/core/lexicon.json
+++ b/core/lexicon.json
@@ -20,7 +20,7 @@
     {"name": "field_contact_role", "description": null},
     {"name": "geochronology", "description": null},
     {"name": "horizontal_datum", "description": null},
-    {"name": "level_status", "description": null},
+    {"name": "value_reason", "description": null},
     {"name": "measurement_method", "description": null},
     {"name": "monitoring_status", "description": null},
     {"name": "observed_property", "description": null},
@@ -284,29 +284,30 @@
     {"categories": ["thing_type"], "term": "perennial stream", "definition": "that has a continuous flow of water throughout the year, even during drier periods."},
     {"categories": ["thing_type"], "term": "ephemeral stream", "definition": "a stream that flows only briefly during and after precipitation events"},
     {"categories": ["thing_type"], "term": "meteorological station", "definition": "a station that measures the weather conditions at a particular location"},
-    {"categories": ["level_status"], "term": "Water level affected by atmospheric pressure", "definition": "Water level affected by atmospheric pressure"},
-    {"categories": ["level_status"], "term": "Water level was frozen (no level recorded).", "definition": "Water level was frozen (no level recorded)."},
-    {"categories": ["level_status"], "term": "Site was dry", "definition": "Site was dry"},
-    {"categories": ["level_status"], "term": "Site was flowing recently.", "definition": "Site was flowing recently."},
-    {"categories": ["level_status"], "term": "Site was flowing. Water level or head couldn't be measured w/out additional equipment.", "definition": "Site was flowing. Water level or head couldn't be measured w/out additional equipment."},
-    {"categories": ["level_status"], "term": "Nearby site that taps the same aquifer was flowing.", "definition": "Nearby site that taps the same aquifer was flowing."},
-    {"categories": ["level_status"], "term": "Nearby site that taps the same aquifer had been flowing recently.", "definition": "Nearby site that taps the same aquifer had been flowing recently."},
-    {"categories": ["level_status"], "term": "Recharge water was being injected into the aquifer at this site.", "definition": "Recharge water was being injected into the aquifer at this site."},
-    {"categories": ["level_status"], "term": "Recharge water was being injected into nearby site that taps the same aquifer.", "definition": "Recharge water was being injected into nearby site that taps the same aquifer."},
-    {"categories": ["level_status"], "term": "Water was cascading down the inside of the well.", "definition": "Water was cascading down the inside of the well."},
-    {"categories": ["level_status"], "term": "Water level was affected by brackish or saline water.", "definition": "Water level was affected by brackish or saline water."},
-    {"categories": ["level_status"], "term": "Well was not in hydraulic contact w/formation (from source other than defined in USGS C714 or C93).", "definition": "Well was not in hydraulic contact w/formation (from source other than defined in USGS C714 or C93)."},
-    {"categories": ["level_status"], "term": "Measurement was discontinued (no level recorded).", "definition": "Measurement was discontinued (no level recorded)."},
-    {"categories": ["level_status"], "term": "Obstruction was encountered in the well (no level recorded)", "definition": "Obstruction was encountered in the well (no level recorded)"},
-    {"categories": ["level_status"], "term": "Site was being pumped", "definition": "Site was being pumped"},
-    {"categories": ["level_status"], "term": "Site was pumped recently", "definition": "Site was pumped recently"},
-    {"categories": ["level_status"], "term": "Nearby site that taps the same aquifer was being pumped", "definition": "Nearby site that taps the same aquifer was being pumped"},
-    {"categories": ["level_status"], "term": "Nearby site that taps the same aquifer was pumped recently", "definition": "Nearby site that taps the same aquifer was pumped recently"},
-    {"categories": ["level_status"], "term": "Foreign substance present on the water surface", "definition": "Foreign substance present on the water surface"},
-    {"categories": ["level_status"], "term": "Well was destroyed (no subsequent water levels should be recorded)", "definition": "Well was destroyed (no subsequent water levels should be recorded)"},
-    {"categories": ["level_status"], "term": "Water level affected by stage in nearby surface-water site", "definition": "Water level affected by stage in nearby surface-water site"},
-    {"categories": ["level_status"], "term": "Other conditions exist that would affect the level (remarks)", "definition": "Other conditions exist that would affect the level (remarks)"},
-    {"categories": ["level_status"], "term": "Water level not affected by status", "definition": "Water level not affected by status"},
+    {"categories": ["value_reason"], "term": "Water level affected by atmospheric pressure", "definition": "Water level affected by atmospheric pressure"},
+    {"categories": ["value_reason"], "term": "Water level was frozen (no level recorded).", "definition": "Water level was frozen (no level recorded)."},
+    {"categories": ["value_reason"], "term": "Site was dry", "definition": "Site was dry"},
+    {"categories": ["value_reason"], "term": "Site was flowing recently.", "definition": "Site was flowing recently."},
+    {"categories": ["value_reason"], "term": "Site was flowing. Water level or head couldn't be measured w/out additional equipment.", "definition": "Site was flowing. Water level or head couldn't be measured w/out additional equipment."},
+    {"categories": ["value_reason"], "term": "Nearby site that taps the same aquifer was flowing.", "definition": "Nearby site that taps the same aquifer was flowing."},
+    {"categories": ["value_reason"], "term": "Nearby site that taps the same aquifer had been flowing recently.", "definition": "Nearby site that taps the same aquifer had been flowing recently."},
+    {"categories": ["value_reason"], "term": "Recharge water was being injected into the aquifer at this site.", "definition": "Recharge water was being injected into the aquifer at this site."},
+    {"categories": ["value_reason"], "term": "Recharge water was being injected into nearby site that taps the same aquifer.", "definition": "Recharge water was being injected into nearby site that taps the same aquifer."},
+    {"categories": ["value_reason"], "term": "Water was cascading down the inside of the well.", "definition": "Water was cascading down the inside of the well."},
+    {"categories": ["value_reason"], "term": "Water level was affected by brackish or saline water.", "definition": "Water level was affected by brackish or saline water."},
+    {"categories": ["value_reason"], "term": "Well was not in hydraulic contact w/formation (from source other than defined in USGS C714 or C93).", "definition": "Well was not in hydraulic contact w/formation (from source other than defined in USGS C714 or C93)."},
+    {"categories": ["value_reason"], "term": "Measurement was discontinued (no level recorded).", "definition": "Measurement was discontinued (no level recorded)."},
+    {"categories": ["value_reason"], "term": "Obstruction was encountered in the well (no level recorded)", "definition": "Obstruction was encountered in the well (no level recorded)"},
+    {"categories": ["value_reason"], "term": "Site was being pumped", "definition": "Site was being pumped"},
+    {"categories": ["value_reason"], "term": "Site was pumped recently", "definition": "Site was pumped recently"},
+    {"categories": ["value_reason"], "term": "Nearby site that taps the same aquifer was being pumped", "definition": "Nearby site that taps the same aquifer was being pumped"},
+    {"categories": ["value_reason"], "term": "Nearby site that taps the same aquifer was pumped recently", "definition": "Nearby site that taps the same aquifer was pumped recently"},
+    {"categories": ["value_reason"], "term": "Foreign substance present on the water surface", "definition": "Foreign substance present on the water surface"},
+    {"categories": ["value_reason"], "term": "Well was destroyed (no subsequent water levels should be recorded)", "definition": "Well was destroyed (no subsequent water levels should be recorded)"},
+    {"categories": ["value_reason"], "term": "Water level affected by stage in nearby surface-water site", "definition": "Water level affected by stage in nearby surface-water site"},
+    {"categories": ["value_reason"], "term": "Other conditions exist that would affect the level (remarks)", "definition": "Other conditions exist that would affect the level (remarks)"},
+    {"categories": ["value_reason"], "term": "Water level not affected by status", "definition": "Water level not affected by status"},
+    {"categories": ["value_reason"], "term": "Observed value not affected", "definition": "Observed value not affected"},
     {"categories": ["status"], "term": "Abandoned", "definition": "Abandoned"},
     {"categories": ["status"], "term": "Active, pumping well", "definition": "Active, pumping well"},
     {"categories": ["status"], "term": "Destroyed, exists but not usable", "definition": "Destroyed, exists but not usable"},
diff --git a/db/contact.py b/db/contact.py
index 83a87cc39..3f4995f67 100644
--- a/db/contact.py
+++ b/db/contact.py
@@ -21,12 +21,12 @@
 
 from db.base import Base, AutoBaseMixin, ReleaseMixin, lexicon_term
 
+
 if TYPE_CHECKING:
+    from db.field import FieldEventParticipant, FieldEvent
     from db.thing import Thing
-    from db.field import FieldEvent
-    from db.field import FieldEventParticipants
+    from db.publication import Author, AuthorContactAssociation
     from db.permission import Permission
-    from db.publication import AuthorContactAssociation, Author
 
 
 class ThingContactAssociation(Base, AutoBaseMixin):
@@ -42,7 +42,7 @@ class ThingContactAssociation(Base, AutoBaseMixin):
     )
     thing: Mapped["Thing"] = relationship(
         "Thing", back_populates="contact_associations"
-    )  # noqa: F821
+    )
 
 
 class Contact(Base, AutoBaseMixin, ReleaseMixin):
@@ -85,8 +85,8 @@ class Contact(Base, AutoBaseMixin, ReleaseMixin):
         cascade="all, delete-orphan",
     )
     # One-To-Many: A Contact can participate in many Field Events.
-    field_event_participants: Mapped[list["FieldEventParticipants"]] = relationship(
-        "FieldEventParticipants",
+    field_event_participants: Mapped[list["FieldEventParticipant"]] = relationship(
+        "FieldEventParticipant",
         back_populates="contact",
         cascade="all, delete-orphan",
         passive_deletes=True,
diff --git a/db/field.py b/db/field.py
index 2aaef2726..551859dcc 100644
--- a/db/field.py
+++ b/db/field.py
@@ -2,12 +2,17 @@
 from sqlalchemy import DateTime, ForeignKey
 from sqlalchemy.orm import mapped_column, relationship, Mapped
 from sqlalchemy.ext.associationproxy import association_proxy, AssociationProxy
+from typing import TYPE_CHECKING
 
 from db.base import Base, AutoBaseMixin, ReleaseMixin, lexicon_term
-from db.contact import Contact
 
+if TYPE_CHECKING:
+    from db.contact import Contact
+    from db.sample import Sample
+    from db.thing import Thing
 
-class FieldEventParticipants(Base, AutoBaseMixin, ReleaseMixin):
+
+class FieldEventParticipant(Base, AutoBaseMixin, ReleaseMixin):
     """
     This association table is to create a many-to-many relationship between
     FieldEvent and Contact. These are participants in the field event.
@@ -34,15 +39,15 @@ class FieldEventParticipants(Base, AutoBaseMixin, ReleaseMixin):
     field_event: Mapped["FieldEvent"] = relationship(
         "FieldEvent", back_populates="field_event_participants"
     )
-    contact: Mapped["Contact"] = relationship(  # noqa: F821
+    contact: Mapped["Contact"] = relationship(
         "Contact", back_populates="field_event_participants"
     )
 
     # map associated contacts to samples to restrict the people who could have
     # taken a sample to those present at the field event
-    samples: Mapped[list["Sample"]] = relationship(  # noqa: F821
+    samples: Mapped[list["Sample"]] = relationship(
         "Sample",
-        back_populates="field_event_contact",
+        back_populates="field_event_participant",
         passive_deletes=True,
     )
 
@@ -60,7 +65,7 @@ class FieldEvent(Base, AutoBaseMixin, ReleaseMixin):
 
     Its purpose is to store the "where and when" of the event.
     Information about who participated is managed in the
-    FieldEventContactAssociation table. Information about the "what" of the
+    FieldEventParticipant table. Information about the "what" of the
     event is managed in the FieldActivity and Sample tables.
     """
 
@@ -82,12 +87,12 @@ class FieldEvent(Base, AutoBaseMixin, ReleaseMixin):
         comment="Notes or comments about the field event.",
     )
     # --- Relationships ---
-    thing: Mapped["Thing"] = relationship(back_populates="field_events")  # noqa: F821
+    thing: Mapped["Thing"] = relationship(back_populates="field_events")
     field_activities: Mapped[list["FieldActivity"]] = relationship(
         "FieldActivity", back_populates="field_event"
     )
-    field_event_participants: Mapped[list["FieldEventParticipants"]] = relationship(
-        "FieldEventParticipants",
+    field_event_participants: Mapped[list["FieldEventParticipant"]] = relationship(
+        "FieldEventParticipant",
         back_populates="field_event",
         cascade="all, delete-orphan",
         passive_deletes=True,
@@ -95,7 +100,7 @@ class FieldEvent(Base, AutoBaseMixin, ReleaseMixin):
 
     # --- Association Proxies ---
     # Proxy to directly access the Contact objects participating in this event.
-    contacts: AssociationProxy[list["Contact"]] = association_proxy(  # noqa: F821
+    contacts: AssociationProxy[list["Contact"]] = association_proxy(
         "field_event_participants", "contact"
     )
 
@@ -136,7 +141,7 @@ class FieldActivity(Base, AutoBaseMixin, ReleaseMixin):
     field_event: Mapped["FieldEvent"] = relationship(
         "FieldEvent", back_populates="field_activities"
     )
-    samples: Mapped[list["Sample"]] = relationship(  # noqa: F821
+    samples: Mapped[list["Sample"]] = relationship(
         "Sample",
         back_populates="field_activity",
         cascade="all, delete-orphan",
diff --git a/db/location.py b/db/location.py
index 102590606..6ef7ce8f5 100644
--- a/db/location.py
+++ b/db/location.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 # ===============================================================================
 import datetime
-
+from typing import TYPE_CHECKING
 from geoalchemy2 import Geometry, WKBElement
 from geoalchemy2.shape import to_shape
 
@@ -34,6 +34,9 @@
 from db.base import Base, AutoBaseMixin, ReleaseMixin
 from db.lexicon import lexicon_term
 
+if TYPE_CHECKING:
+    from db.thing import Thing
+
 
 class Location(Base, AutoBaseMixin, ReleaseMixin):
     __versioned__ = {}
@@ -67,7 +70,7 @@ class Location(Base, AutoBaseMixin, ReleaseMixin):
     )
 
     # --- Proxy Definitions ---
-    things: AssociationProxy[list["Thing"]] = association_proxy(  # noqa: F821
+    things: AssociationProxy[list["Thing"]] = association_proxy(
         "thing_associations", "thing"
     )
 
@@ -97,9 +100,7 @@ class LocationThingAssociation(Base, AutoBaseMixin):
 
     # --- Relationship Definitions ---
     location: Mapped["Location"] = relationship(back_populates="thing_associations")
-    thing: Mapped["Thing"] = relationship(  # noqa: F821
-        back_populates="location_associations"
-    )
+    thing: Mapped["Thing"] = relationship(back_populates="location_associations")
 
 
 # ============= EOF =============================================
diff --git a/db/observation.py b/db/observation.py
index af737a7cf..588b77d0a 100644
--- a/db/observation.py
+++ b/db/observation.py
@@ -59,6 +59,11 @@ class Observation(Base, AutoBaseMixin, ReleaseMixin):
         nullable=True,
     )
     unit: Mapped[str] = lexicon_term(nullable=False)
+    value_reason: Mapped[str] = lexicon_term(
+        nullable=False,
+        comment="The reason describes everything that can effect the observation the moment a sample/observation is attempted (e.g. obstruction, dry well, equipment failure); a null value must have an associated reason in the same record. Factors preventing the obtainment of the observation from the beginning of the field event to attempted sampling/observation (e.g. flat tire, locked gate, destroyed well) are not recorded here but in the notes field of the FieldEvent table; in this situation no sample/observation should be recorded.",
+    )
+    notes: Mapped[str] = mapped_column(nullable=True)
 
     # groundwater
     measuring_point_height: Mapped[float] = mapped_column(
@@ -67,25 +72,16 @@ class Observation(Base, AutoBaseMixin, ReleaseMixin):
         info={"unit": "ft"},
     )
 
-    level_status: Mapped[str] = lexicon_term(nullable=True)
-
-    # geothermal
-    observation_depth: Mapped[float] = mapped_column(
-        nullable=True,
-        info={"unit": "feet"},
-        doc="Depth of the geothermal observation in feet",
-    )
-
     # --- Relationships ---
     # Many-To-One: An Observation can be generated by one piece of Equipment.
-    sensor: Mapped["Sensor"] = relationship(  # noqa: F821
+    sensor: Mapped["Sensor"] = relationship(
         "Sensor", back_populates="observations", passive_deletes=True
-    )  # noqa: F821
+    )
 
     # Many-To-One: An Observation is derived from one Sample.
-    sample: Mapped["Sample"] = relationship(  # noqa: F821
+    sample: Mapped["Sample"] = relationship(
         "Sample", back_populates="observations", passive_deletes=True
-    )  # noqa: F821
+    )
 
     # Many-To-One: An Observation can be generated using one AnalysisMethod.
     analysis_method: Mapped["AnalysisMethod"] = relationship(
diff --git a/db/publication.py b/db/publication.py
index 2eec8213a..9cfda90f0 100644
--- a/db/publication.py
+++ b/db/publication.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 # ===============================================================================
 from sqlalchemy_utils import TSVectorType
+from typing import TYPE_CHECKING
 
 from db import lexicon_term
 from db.base import AutoBaseMixin, Base, AuditMixin
@@ -22,6 +23,10 @@
 from sqlalchemy.ext.associationproxy import association_proxy, AssociationProxy
 
 
+if TYPE_CHECKING:
+    from db.contact import Contact
+
+
 class Publication(Base, AutoBaseMixin):
 
     title = Column(Text, nullable=False)
@@ -76,7 +81,7 @@ class Author(Base, AutoBaseMixin):
         back_populates="author",
         cascade="all, delete-orphan",
     )
-    contacts: AssociationProxy[list["Contact"]] = association_proxy(  # noqa: F821
+    contacts: AssociationProxy[list["Contact"]] = association_proxy(
         "author_associations", "contact"
     )
 
diff --git a/db/sample.py b/db/sample.py
index 2128d5635..04e647c62 100644
--- a/db/sample.py
+++ b/db/sample.py
@@ -24,7 +24,7 @@
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
-    from db.field import FieldEvent, FieldActivity, FieldEventParticipants
+    from db.field import FieldEvent, FieldActivity, FieldEventParticipant
     from db.thing import Thing
     from db.contact import Contact
     from db.observation import Observation
@@ -50,8 +50,8 @@ class Sample(Base, AutoBaseMixin, ReleaseMixin):
         ForeignKey("field_activity.id"), nullable=False
     )
 
-    field_event_contact_id: Mapped[str] = mapped_column(
-        ForeignKey("field_event_participants.id"), nullable=True
+    field_event_participant_id: Mapped[str] = mapped_column(
+        ForeignKey("field_event_participant.id"), nullable=True
     )
 
     # --- Columns ---
@@ -92,7 +92,7 @@ class Sample(Base, AutoBaseMixin, ReleaseMixin):
 
     # --- Relationship Definitions ---
     field_activity: Mapped["FieldActivity"] = relationship(back_populates="samples")
-    field_event_contact: Mapped["FieldEventParticipants"] = relationship(
+    field_event_participant: Mapped["FieldEventParticipant"] = relationship(
         back_populates="samples"
     )
 
@@ -104,7 +104,7 @@ class Sample(Base, AutoBaseMixin, ReleaseMixin):
         "field_activity", "field_event.thing"
     )
     contact: AssociationProxy["Contact"] = association_proxy(
-        "field_event_contact", "contact"
+        "field_event_participant", "contact"
     )
     observations: Mapped[list["Observation"]] = relationship(
         "Observation",
diff --git a/db/sensor.py b/db/sensor.py
index bc3f243fb..5face8a96 100644
--- a/db/sensor.py
+++ b/db/sensor.py
@@ -50,7 +50,7 @@ class Sensor(Base, AutoBaseMixin, ReleaseMixin):
 
     # --- Relationships ---
     # One-To-Many: A piece of Equipment can generate many Observations.
-    observations: Mapped[List["Observation"]] = relationship(  # noqa: F821
+    observations: Mapped[List["Observation"]] = relationship(
         "Observation",
         back_populates="sensor",
     )
diff --git a/schemas/observation.py b/schemas/observation.py
index 1e052fec3..819547095 100644
--- a/schemas/observation.py
+++ b/schemas/observation.py
@@ -64,21 +64,17 @@ class CreateBaseObservation(BaseCreateModel, ValidateObservation):
     release_status: str
     value: float | None
     unit: str | None
+    value_reason: str
 
 
 class CreateGroundwaterLevelObservation(CreateBaseObservation):
     measuring_point_height: float
-    level_status: str
 
 
 class CreateWaterChemistryObservation(CreateBaseObservation):
     pass
 
 
-# class CreateGeothermalObservation(CreateBaseObservation):
-#     observation_depth: float
-
-
 # -------- UPDATE ------------
 
 
@@ -90,21 +86,17 @@ class UpdateBaseObservation(BaseUpdateModel, ValidateObservation):
     release_status: str | None = None
     value: float | None | None = None
     unit: str | None = None
+    value_reason: str | None = None
 
 
 class UpdateGroundwaterLevelObservation(UpdateBaseObservation):
     measuring_point_height: float | None = None
-    level_status: str | None = None
 
 
 class UpdateWaterChemistryObservation(UpdateBaseObservation):
     pass
 
 
-# class UpdateGeothermalObservation(UpdateBaseObservation):
-#     observation_depth: float | None = None
-
-
 # -------- RESPONSE ----------
 class BaseObservationResponse(BaseResponseModel):
     sample_id: int
@@ -114,12 +106,12 @@ class BaseObservationResponse(BaseResponseModel):
     release_status: str
     value: float | None
     unit: str
+    value_reason: str
 
 
 class GroundwaterLevelObservationResponse(BaseObservationResponse):
     depth_to_water_bgs: float | None
     measuring_point_height: float | None
-    level_status: str | None
 
     @model_validator(mode="before")
     def calculate_depth_to_water_bgs(self: Self) -> Self:
@@ -136,10 +128,6 @@ class WaterChemistryObservationResponse(BaseObservationResponse):
     pass
 
 
-# class GeothermalObservationResponse(BaseObservationResponse):
-#     observation_depth: float | None
-
-
 class ObservationResponse(
     GroundwaterLevelObservationResponse, WaterChemistryObservationResponse
 ):
diff --git a/schemas/sample.py b/schemas/sample.py
index 44a29aef9..43c364beb 100644
--- a/schemas/sample.py
+++ b/schemas/sample.py
@@ -84,7 +84,7 @@ def convert_sample_date_to_utc(sample_date: AwareDatetime) -> AwareDatetime:
 # -------- CREATE ----------
 class CreateSample(BaseCreateModel, ValidateSample):
     field_activity_id: int
-    field_event_contact_id: int
+    field_event_participant_id: int
     sample_date: Annotated[AwareDatetime, PastDatetime()]
     sample_name: str
     sample_matrix: str
@@ -98,7 +98,7 @@ class CreateSample(BaseCreateModel, ValidateSample):
 # -------- UPDATE ----------
 class UpdateSample(BaseUpdateModel, ValidateSample):
     field_activity_id: int | None = None  # TODO: should this be editable?
-    field_event_contact_id: int | None = None
+    field_event_participant_id: int | None = None
     sample_date: Annotated[AwareDatetime, PastDatetime()] | None = None
     sample_name: str | None = None
     sample_matrix: str | None = None
@@ -124,8 +124,6 @@ class SampleResponse(BaseResponseModel):
     field_event: FieldEventResponse
     field_activity: FieldActivityResponse
     contact: ContactResponse
-    # field_activity_id: int
-    # field_event_contact_id: int
     sample_date: Annotated[AwareDatetime, PastDatetime()]
     sample_name: str
     sample_matrix: str
diff --git a/services/observation_helper.py b/services/observation_helper.py
index 7d935c346..650c66a28 100644
--- a/services/observation_helper.py
+++ b/services/observation_helper.py
@@ -12,7 +12,6 @@
 from schemas.observation import (
     ObservationResponse,
     WaterChemistryObservationResponse,
-    # GeothermalObservationResponse,
     GroundwaterLevelObservationResponse,
 )
 from services.exceptions_helper import PydanticStyleException
@@ -47,7 +46,6 @@ def get_observations(
 ) -> (
     List[ObservationResponse]
     | List[WaterChemistryObservationResponse]
-    # | List[GeothermalObservationResponse]
     | List[GroundwaterLevelObservationResponse]
 ):
     """
diff --git a/services/sample_helper.py b/services/sample_helper.py
index f98bf6e07..e8fecab4d 100644
--- a/services/sample_helper.py
+++ b/services/sample_helper.py
@@ -1,7 +1,7 @@
 from sqlalchemy.orm import Session, joinedload
 from fastapi_pagination.ext.sqlalchemy import paginate
 
-from db import FieldEvent, FieldActivity, FieldEventParticipants, Sample
+from db import FieldEvent, FieldActivity, FieldEventParticipant, Sample
 from services.query_helper import order_sort_filter
 
 
@@ -17,8 +17,8 @@ def get_db_samples(
         joinedload(Sample.field_activity)
         .joinedload(FieldActivity.field_event)
         .joinedload(FieldEvent.thing),
-        joinedload(Sample.field_event_contact).joinedload(
-            FieldEventParticipants.contact
+        joinedload(Sample.field_event_participant).joinedload(
+            FieldEventParticipant.contact
         ),  # Eagerly load related Contact
     )
 
diff --git a/tests/conftest.py b/tests/conftest.py
index ed00d4277..062cf5e9f 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -496,16 +496,16 @@ def field_event(water_well_thing):
 
 
 @pytest.fixture(scope="session")
-def field_event_contact(field_event, contact):
+def field_event_participant(field_event, contact):
     with session_ctx() as session:
-        field_event_contact = FieldEventParticipants(
+        field_event_participant = FieldEventParticipant(
             field_event_id=field_event.id,
             contact_id=contact.id,
             field_contact_role="Lead",
         )
-        session.add(field_event_contact)
+        session.add(field_event_participant)
         session.commit()
-        yield field_event_contact
+        yield field_event_participant
 
 
 @pytest.fixture(scope="session")
@@ -537,11 +537,11 @@ def water_chemistry_field_activity(field_event):
 
 
 @pytest.fixture(scope="session")
-def groundwater_level_sample(groundwater_level_field_activity, field_event_contact):
+def groundwater_level_sample(groundwater_level_field_activity, field_event_participant):
     with session_ctx() as session:
         sample = Sample(
             field_activity_id=groundwater_level_field_activity.id,
-            field_event_contact_id=field_event_contact.id,
+            field_event_participant_id=field_event_participant.id,
             sample_date="2025-01-01T12:00:00Z",
             sample_name="groundwater level sample name",
             sample_matrix="water",
@@ -558,11 +558,11 @@ def groundwater_level_sample(groundwater_level_field_activity, field_event_conta
 
 
 @pytest.fixture(scope="session")
-def water_chemistry_sample(water_chemistry_field_activity, field_event_contact):
+def water_chemistry_sample(water_chemistry_field_activity, field_event_participant):
     with session_ctx() as session:
         sample = Sample(
             field_activity_id=water_chemistry_field_activity.id,
-            field_event_contact_id=field_event_contact.id,
+            field_event_participant_id=field_event_participant.id,
             sample_date="2025-01-01T13:00:00Z",
             sample_name="water chemistry sample name",
             sample_matrix="water",
@@ -579,11 +579,11 @@ def water_chemistry_sample(water_chemistry_field_activity, field_event_contact):
 
 
 @pytest.fixture(scope="function")
-def sample_to_delete(water_chemistry_field_activity, field_event_contact):
+def sample_to_delete(water_chemistry_field_activity, field_event_participant):
     with session_ctx() as session:
         sample = Sample(
             field_activity_id=water_chemistry_field_activity.id,
-            field_event_contact_id=field_event_contact.id,
+            field_event_participant_id=field_event_participant.id,
             sample_date="2025-01-01T13:00:00Z",
             sample_name="sample to delete",
             sample_matrix="water",
@@ -613,7 +613,7 @@ def groundwater_level_observation(sensor, groundwater_level_sample):
             value=10.0,
             unit="ft",
             measuring_point_height=5.0,
-            level_status="Water level not affected by status",
+            value_reason="Water level not affected by status",
         )
         session.add(observation)
         session.commit()
@@ -631,24 +631,7 @@ def water_chemistry_observation(sensor, water_chemistry_sample):
             release_status="draft",
             value=4.0,
             unit="dimensionless",
-        )
-        session.add(observation)
-        session.commit()
-        yield observation
-
-
-@pytest.fixture(scope="session")
-def geothermal_observation(sensor, geothermal_sample):
-    with session_ctx() as session:
-        observation = Observation(
-            observation_datetime="2025-01-01T00:02:00Z",
-            sample_id=geothermal_sample.id,
-            sensor_id=sensor.id,
-            observed_property="temperature",
-            release_status="draft",
-            value=20.0,
-            unit="deg C",
-            observation_depth=200.0,
+            value_reason="Observed value not affected",
         )
         session.add(observation)
         session.commit()
@@ -666,6 +649,7 @@ def observation_to_delete(water_chemistry_sample, sensor):
             release_status="draft",
             value=4.0,
             unit="dimensionless",
+            value_reason="Observed value not affected",
         )
         session.add(observation)
         session.commit()
diff --git a/tests/test_observation.py b/tests/test_observation.py
index ec1c73060..ede2c90ca 100644
--- a/tests/test_observation.py
+++ b/tests/test_observation.py
@@ -55,6 +55,7 @@ def test_add_water_chemistry_observation(water_chemistry_sample, sensor):
         "sample_id": water_chemistry_sample.id,
         "sensor_id": sensor.id,
         "observed_property": "pH",
+        "value_reason": "Observed value not affected",
     }
     response = client.post("/observation/water-chemistry", json=payload)
     data = response.json()
@@ -69,6 +70,7 @@ def test_add_water_chemistry_observation(water_chemistry_sample, sensor):
     assert data["sample_id"] == payload["sample_id"]
     assert data["sensor_id"] == payload["sensor_id"]
     assert data["observed_property"] == payload["observed_property"]
+    assert data["value_reason"] == payload["value_reason"]
 
     cleanup_post_test(Observation, data["id"])
 
@@ -81,7 +83,7 @@ def test_add_groundwater_level_observation(groundwater_level_sample, sensor):
         "measuring_point_height": 53,
         "sample_id": groundwater_level_sample.id,
         "sensor_id": sensor.id,
-        "level_status": "Water level not affected by status",
+        "value_reason": "Water level not affected by status",
         "observed_property": "groundwater level",
         "unit": "ft",
     }
@@ -96,7 +98,7 @@ def test_add_groundwater_level_observation(groundwater_level_sample, sensor):
     assert data["value"] == payload["value"]
     assert data["measuring_point_height"] == payload["measuring_point_height"]
     assert data["sensor_id"] == payload["sensor_id"]
-    assert data["level_status"] == payload["level_status"]
+    assert data["value_reason"] == payload["value_reason"]
     assert data["observed_property"] == payload["observed_property"]
     assert (
         data["depth_to_water_bgs"]
@@ -106,35 +108,6 @@ def test_add_groundwater_level_observation(groundwater_level_sample, sensor):
     cleanup_post_test(Observation, data["id"])
 
 
-# def test_add_geothermal_observation(geothermal_sample, sensor):
-#     payload = {
-#         "observation_datetime": "2025-01-01T00:00:00Z",
-#         "release_status": "draft",
-#         "observation_depth": 100,
-#         "value": 25.5,
-#         "sample_id": geothermal_sample.id,
-#         "sensor_id": sensor.id,
-#         "observed_property": "temperature",
-#         "unit": "deg C",
-#     }
-#     response = client.post("/observation/geothermal", json=payload)
-#     data = response.json()
-#     assert response.status_code == 201
-
-#     assert "id" in data
-#     assert "created_at" in data
-#     assert data["observation_datetime"] == payload["observation_datetime"]
-#     assert data["release_status"] == payload["release_status"]
-#     assert data["observation_depth"] == payload["observation_depth"]
-#     assert data["value"] == payload["value"]
-#     assert data["sample_id"] == payload["sample_id"]
-#     assert data["sensor_id"] == payload["sensor_id"]
-#     assert data["observed_property"] == payload["observed_property"]
-#     assert data["unit"] == payload["unit"]
-
-#     cleanup_post_test(Observation, data["id"])
-
-
 # PATCH tests ==================================================================
 
 
@@ -224,48 +197,6 @@ def test_patch_water_chemistry_observation_404_wrong_activity_type(
     )
 
 
-# def test_patch_geothermal_observation(geothermal_observation):
-#     payload = {"observation_depth": 4, "release_status": "private"}
-#     response = client.patch(
-#         f"/observation/geothermal/{geothermal_observation.id}", json=payload
-#     )
-#     assert response.status_code == 200
-#     data = response.json()
-#     assert data["observation_depth"] == payload["observation_depth"]
-#     assert data["release_status"] == payload["release_status"]
-
-#     cleanup_patch_test(Observation, payload, geothermal_observation)
-
-
-# def test_patch_geothermal_observation_404_not_found(geothermal_observation):
-#     bad_id = 999999
-#     payload = {"observation_depth": 8}
-#     response = client.patch(f"/observation/geothermal/{bad_id}", json=payload)
-#     assert response.status_code == 404
-#     data = response.json()
-#     assert data["detail"] == f"Observation with ID {bad_id} not found."
-
-
-# def test_patch_geothermal_observation_404_wrong_activity_type(
-#     groundwater_level_observation, water_chemistry_observation
-# ):
-#     for obs in groundwater_level_observation, water_chemistry_observation:
-#         payload = {"value": 8}
-#         response = client.patch(f"/observation/geothermal/{obs.id}", json=payload)
-#         assert response.status_code == 404
-#         data = response.json()
-
-#         if obs.observed_property == "groundwater level":
-#             activity_type = "groundwater level"
-#         else:
-#             activity_type = "water chemistry"
-
-#         assert (
-#             data["detail"][0]["msg"]
-#             == f"Observation with ID {obs.id} is not a geothermal observation. It is a {activity_type} observation."
-#         )
-
-
 # ============= Get tests =================
 
 
@@ -344,7 +275,7 @@ def test_get_groundwater_level_observations(groundwater_level_observation):
         == groundwater_level_observation.release_status
     )
     assert (
-        data["items"][0]["level_status"] == groundwater_level_observation.level_status
+        data["items"][0]["value_reason"] == groundwater_level_observation.value_reason
     )
     assert data["items"][0]["value"] == groundwater_level_observation.value
     assert data["items"][0]["unit"] == groundwater_level_observation.unit
@@ -358,7 +289,7 @@ def test_get_groundwater_level_observations(groundwater_level_observation):
         == groundwater_level_observation.measuring_point_height
     )
     assert (
-        data["items"][0]["level_status"] == groundwater_level_observation.level_status
+        data["items"][0]["value_reason"] == groundwater_level_observation.value_reason
     )
 
 
@@ -384,7 +315,7 @@ def test_get_groundwater_level_observation_by_id(groundwater_level_observation):
         == groundwater_level_observation.observed_property[colon_index + 1 :]
     )
     assert data["release_status"] == groundwater_level_observation.release_status
-    assert data["level_status"] == groundwater_level_observation.level_status
+    assert data["value_reason"] == groundwater_level_observation.value_reason
     assert data["value"] == groundwater_level_observation.value
     assert data["unit"] == groundwater_level_observation.unit
     assert (
@@ -396,7 +327,7 @@ def test_get_groundwater_level_observation_by_id(groundwater_level_observation):
         data["measuring_point_height"]
         == groundwater_level_observation.measuring_point_height
     )
-    assert data["level_status"] == groundwater_level_observation.level_status
+    assert data["value_reason"] == groundwater_level_observation.value_reason
 
 
 def test_get_groundwater_level_observation_by_id_404_not_found(
@@ -592,87 +523,6 @@ def test_get_water_chemistry_observation_by_id_404_wrong_activity_type(
     assert data["detail"][0]["loc"] == ["path", "observation_id"]
 
 
-# def test_get_geothermal_observations(geothermal_observation):
-#     response = client.get("/observation/geothermal")
-#     assert response.status_code == 200
-#     data = response.json()
-#     assert data["total"] == 1
-#     assert data["items"][0]["id"] == geothermal_observation.id
-#     assert data["items"][0][
-#         "created_at"
-#     ] == geothermal_observation.created_at.isoformat().replace("+00:00", "Z")
-#     assert data["items"][0]["release_status"] == geothermal_observation.release_status
-#     assert data["items"][0]["sample_id"] == geothermal_observation.sample_id
-#     assert data["items"][0]["sensor_id"] == geothermal_observation.sensor_id
-#     assert (
-#         data["items"][0]["observation_datetime"]
-#         == geothermal_observation.observation_datetime
-#     )
-#     colon_index = geothermal_observation.observed_property.find(":")
-#     assert (
-#         data["items"][0]["observed_property"]
-#         == geothermal_observation.observed_property[colon_index + 1 :]
-#     )
-#     assert data["items"][0]["value"] == geothermal_observation.value
-#     assert data["items"][0]["unit"] == geothermal_observation.unit
-#     assert (
-#         data["items"][0]["observation_depth"]
-#         == geothermal_observation.observation_depth
-#     )
-
-
-# def test_get_geothermal_observation_by_id(geothermal_observation):
-#     response = client.get(f"/observation/geothermal/{geothermal_observation.id}")
-#     assert response.status_code == 200
-#     data = response.json()
-#     assert data["id"] == geothermal_observation.id
-#     assert data["created_at"] == geothermal_observation.created_at.isoformat().replace(
-#         "+00:00", "Z"
-#     )
-#     assert data["release_status"] == geothermal_observation.release_status
-#     assert data["sample_id"] == geothermal_observation.sample_id
-#     assert data["sensor_id"] == geothermal_observation.sensor_id
-#     assert data["observation_datetime"] == geothermal_observation.observation_datetime
-#     colon_index = geothermal_observation.observed_property.find(":")
-#     assert (
-#         data["observed_property"]
-#         == geothermal_observation.observed_property[colon_index + 1 :]
-#     )
-#     assert data["value"] == geothermal_observation.value
-#     assert data["unit"] == geothermal_observation.unit
-#     assert data["observation_depth"] == geothermal_observation.observation_depth
-
-
-# def test_get_geothermal_observation_by_id_404_not_found(geothermal_observation):
-#     bad_id = 99999
-#     response = client.get(f"/observation/geothermal/{bad_id}")
-#     assert response.status_code == 404
-#     data = response.json()
-#     assert data["detail"] == f"Observation with ID {bad_id} not found."
-
-
-# def test_get_geothermal_observation_by_id_404_wrong_activity_type(
-#     water_chemistry_observation, groundwater_level_observation
-# ):
-#     for obs in water_chemistry_observation, groundwater_level_observation:
-#         response = client.get(f"/observation/geothermal/{obs.id}")
-#         assert response.status_code == 404
-#         data = response.json()
-
-#         if obs.observed_property == "groundwater level":
-#             actual_activity_type = "groundwater level"
-#         else:
-#             actual_activity_type = "water chemistry"
-
-#         assert (
-#             data["detail"][0]["msg"]
-#             == f"Observation with ID {obs.id} is not a geothermal observation. It is a {actual_activity_type} observation."
-#         )
-#         assert data["detail"][0]["type"] == "value_error"
-#         assert data["detail"][0]["input"] == {"observation_id": obs.id}
-#         assert data["detail"][0]["loc"] == ["path", "observation_id"]
-
-
 # JB's comment: I don't think that geographic filters are necessary for
 # observations. I think that they should only be applicable to finding Things
 # and locations. Then the user can proceed from there to find observations.
diff --git a/tests/test_sample.py b/tests/test_sample.py
index 4f5a301ee..c7fb83ee2 100644
--- a/tests/test_sample.py
+++ b/tests/test_sample.py
@@ -54,14 +54,14 @@ def test_validate_sample_top_and_bottom():
 
 #  ============= Post tests for samples =============================================
 def test_add_sample(
-    groundwater_level_field_activity, water_well_thing, contact, field_event_contact
+    groundwater_level_field_activity, water_well_thing, contact, field_event_participant
 ):
     """
     Test adding a sample.
     """
     payload = {
         "field_activity_id": groundwater_level_field_activity.id,
-        "field_event_contact_id": field_event_contact.id,
+        "field_event_participant_id": field_event_participant.id,
         "sample_date": "2025-01-01T14:00:00Z",
         "sample_name": "second groundwater level field activity name",
         "sample_matrix": "water",
@@ -102,14 +102,14 @@ def test_add_sample(
 def test_409_add_sample_invalid_sample_name(
     groundwater_level_field_activity,
     groundwater_level_sample,
-    field_event_contact,
+    field_event_participant,
 ):
     """
     Test that a 409 error is raised if a duplicate sample_name is in the payload
     """
     payload = {
         "field_activity_id": groundwater_level_field_activity.id,
-        "field_event_contact_id": field_event_contact.id,
+        "field_event_participant_id": field_event_participant.id,
         "sample_date": "2025-01-01T14:00:00Z",
         "sample_name": groundwater_level_sample.sample_name,
         "sample_matrix": "water",
@@ -139,14 +139,14 @@ def test_409_add_sample_invalid_sample_name(
 def test_409_add_sample_invalid_field_activity_id(
     groundwater_level_field_activity,
     groundwater_level_sample,
-    field_event_contact,
+    field_event_participant,
 ):
     """
     Test adding a sample with an invalid field_activity_id.
     """
     payload = {
         "field_activity_id": 999999,
-        "field_event_contact_id": field_event_contact.id,
+        "field_event_participant_id": field_event_participant.id,
         "sample_date": "2025-01-01T14:00:00Z",
         "sample_name": "yet another sample name",
         "sample_matrix": "water",
@@ -161,7 +161,6 @@ def test_409_add_sample_invalid_field_activity_id(
         json=payload,
     )
     data = response.json()
-    print(data)
     assert response.status_code == 409
     assert data["detail"][0]["loc"] == ["body", "field_activity_id"]
     assert (
@@ -196,7 +195,7 @@ def test_patch_sample(water_chemistry_sample, groundwater_level_field_activity):
     data = response.json()
 
     for key, value in payload.items():
-        if key in ["field_event_contact_id", "field_activity_id"]:
+        if key in ["field_event_participant_id", "field_activity_id"]:
             continue
         assert data[key] == value