how to make sure how to makesure water markstrategy is proagated in flink?

If you use Flink Table/Sql API, you could use

describe table_name

.

Flink SQL> create table t1 (id int, ts timestamp(3), watermark for ts as ts - interval '1' minutes) with ('connector'='datagen');
[INFO] Execute statement succeeded.

Flink SQL> desc t1;
+------+------------------------+------+-----+--------+----------------------------+
| name |                   type | null | key | extras |                  watermark |
+------+------------------------+------+-----+--------+----------------------------+
|   id |                    INT | TRUE |     |        |                            |
|   ts | TIMESTAMP(3) *ROWTIME* | TRUE |     |        | `ts` - INTERVAL '1' MINUTE |
+------+------------------------+------+-----+--------+----------------------------+
2 rows in set

could you tell how can we assign water mark strategy in between of stream