Diel cycling of stream parameters is overlooked in typical water quality assessments. With a focus on turbidity, we analyzed cycling at multiple sites in both agricultural drains and natural tributaries of the upper Kalamazoo River watershed, Michigan. Turbidity and other water quality parameters (DO, water level, temperature, specific conductivity, pH, and total suspended solids (TSS)) were frequently monitored (mostly 10-minute intervals) during summers 2010 and 2011. Two study sites in Rice Creek, an agricultural drain, show turbidity increases of 10 to 20 NTU at night with broad noisy peaks between 10 pm and 6 am and daytime saddles between 10 am and 7 pm. Downstream turbidity peaks lag upstream peaks by approximately 2 hours over [...]