diff --git a/.kokoro/presubmit/presubmit.cfg b/.kokoro/presubmit/presubmit.cfg
index fa39b1118..ce3953120 100644
--- a/.kokoro/presubmit/presubmit.cfg
+++ b/.kokoro/presubmit/presubmit.cfg
@@ -2,14 +2,6 @@
 
 # Disable system tests.
 env_vars: {
-    key: "RUN_SYSTEM_TESTS"
-    value: "false"
-}
-env_vars: {
-    key: "RUN_SNIPPETS_TESTS"
-    value: "false"
-}
-env_vars: {
-    key: "RUN_LINTING_TYPING_TESTS"
-    value: "false"
+    key: "NOX_SESSION"
+    value: "unit_noextras unit cover docs"
 }
diff --git a/noxfile.py b/noxfile.py
index 78a9ab5b6..02655a7b7 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -132,10 +132,6 @@ def unit_noextras(session):
 def mypy(session):
     """Run type checks with mypy."""
 
-    # Check the value of `RUN_LINTING_TYPING_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_LINTING_TYPING_TESTS", "true") == "false":
-        session.skip("RUN_LINTING_TYPING_TESTS is set to false, skipping")
-
     session.install("-e", ".[all]")
     session.install(MYPY_VERSION)
 
@@ -157,10 +153,6 @@ def pytype(session):
     # recent version avoids the error until a possibly better fix is found.
     # https://github.com/googleapis/python-bigquery/issues/655
 
-    # Check the value of `RUN_LINTING_TYPING_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_LINTING_TYPING_TESTS", "true") == "false":
-        session.skip("RUN_LINTING_TYPING_TESTS is set to false, skipping")
-
     session.install("attrs==20.3.0")
     session.install("-e", ".[all]")
     session.install(PYTYPE_VERSION)
@@ -176,10 +168,6 @@ def system(session):
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
 
-    # Check the value of `RUN_SYSTEM_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_SYSTEM_TESTS", "true") == "false":
-        session.skip("RUN_SYSTEM_TESTS is set to false, skipping")
-
     # Sanity check: Only run system tests if the environment variable is set.
     if not os.environ.get("GOOGLE_APPLICATION_CREDENTIALS", ""):
         session.skip("Credentials must be set via environment variable.")
@@ -224,10 +212,6 @@ def system(session):
 def mypy_samples(session):
     """Run type checks with mypy."""
 
-    # Check the value of `RUN_LINTING_TYPING_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_LINTING_TYPING_TESTS", "true") == "false":
-        session.skip("RUN_LINTING_TYPING_TESTS is set to false, skipping")
-
     session.install("pytest")
     for requirements_path in CURRENT_DIRECTORY.glob("samples/*/requirements.txt"):
         session.install("-r", str(requirements_path))
@@ -263,10 +247,6 @@ def mypy_samples(session):
 def snippets(session):
     """Run the snippets test suite."""
 
-    # Check the value of `RUN_SNIPPETS_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_SNIPPETS_TESTS", "true") == "false":
-        session.skip("RUN_SNIPPETS_TESTS is set to false, skipping")
-
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
@@ -409,10 +389,6 @@ def lint(session):
     serious code quality issues.
     """
 
-    # Check the value of `RUN_LINTING_TYPING_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_LINTING_TYPING_TESTS", "true") == "false":
-        session.skip("RUN_LINTING_TYPING_TESTS is set to false, skipping")
-
     session.install("flake8", BLACK_VERSION)
     session.install("-e", ".")
     session.run("flake8", os.path.join("google", "cloud", "bigquery"))
@@ -427,10 +403,6 @@ def lint(session):
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
 
-    # Check the value of `RUN_LINTING_TYPING_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_LINTING_TYPING_TESTS", "true") == "false":
-        session.skip("RUN_LINTING_TYPING_TESTS is set to false, skipping")
-
     session.install("docutils", "Pygments")
     session.run("python", "setup.py", "check", "--restructuredtext", "--strict")
 
@@ -441,10 +413,6 @@ def blacken(session):
     Format code to uniform standard.
     """
 
-    # Check the value of `RUN_LINTING_TYPING_TESTS` env var. It defaults to true.
-    if os.environ.get("RUN_LINTING_TYPING_TESTS", "true") == "false":
-        session.skip("RUN_LINTING_TYPING_TESTS is set to false, skipping")
-
     session.install(BLACK_VERSION)
     session.run("black", *BLACK_PATHS)