MN Parks and Trails Council has issued their condition of the trails report for state bike trails for 2019 and it makes good reading. It has some excellent recommendations for suggestions for maintaining the trail network .
The Gateway trail condition is rated excellent - good N of Hwy 36, and fair to poor S of Hwy 36 (where the age of the trail (>25 years) is more apparent). Brown's Creek is rated in excellent condition (however be careful of the very rough bump hazard about 3/8 mile N of Stillwater trailhead (July 3))
The full report is here: 2018-2019-State-of-the-Trails_Web.pdf