It's unclear from imagery where Cottonwood Creek flows under Tutt Boulevard. Esri Worl Imagery and Maxar Premium Imagery are the most up to date. Other sources are from before the extension of Tutt Boulevard across Cottonwood Creek. There is tunnel under Tutt Boulevard, about 30 m north of the current stream crossing location (N38.95076° W104.71429). I will have another look on my next bike ride to this location.