Index: modules/search/search.pages.inc
===================================================================
--- modules/search/search.pages.inc	(revision 1452)
+++ modules/search/search.pages.inc	(working copy)
@@ -59,8 +59,10 @@
     }
     // Only search if there are keywords or non-empty conditions.
     if ($keys || !empty($conditions)) {
-      // Log the search keys.
-      watchdog('search', 'Searched %type for %keys.', array('%keys' => $keys, '%type' => $info['title']), WATCHDOG_NOTICE, l(t('results'), 'search/' . $info['path'] . '/' . $keys));
+      if (variable_get('search_log_searches_to_watchdog', 1)) {
+        // Log the search keys.
+        watchdog('search', 'Searched %type for %keys.', array('%keys' => $keys, '%type' => $info['title']), WATCHDOG_NOTICE, l(t('results'), 'search/' . $info['path'] . '/' . $keys));
+      }
 
       // Collect the search results.
       $results = search_data($keys, $info['module'], $conditions);
Index: sites/default/default.settings.php
===================================================================
--- sites/default/default.settings.php	(revision 1452)
+++ sites/default/default.settings.php	(working copy)
@@ -444,3 +444,12 @@
  * Remove the leading hash signs to disable.
  */
 # $conf['allow_authorize_operations'] = FALSE;
+
+/**
+ * Turn of logging of search queries:
+ *
+ * By default, every search query will be logged by watchdog.
+ *
+ * Remove the leading hash signs to disable.
+ */
+# $conf['search_log_searches_to_watchdog'] = FALSE;