Water-based colorant traced formulations (products) containing one or more water treatment agents, such as phosphonates, polyacrylic acids and/or polymers, co-polymers, terpolymers thereof, azoles, molybdate, polysilicates, phosphates, zinc, polyphosphates, etc., are provided wherein the water-soluble colorant is detectable in the visible light range of about 580-640 nm and is chemically inert relative to the water treatment agent(s). Measurement of an optical property of the colorant in the treated coolant water permits the concentration of the product therein to be ascertained, and the level of the product containing can be adjusted for controlling scale, corrosion, deposition, and/or microbial activity in commercial and/or industrial cooling water systems. These products may be reliably monitored and dosed to maintain a product level in treated water of 5 to 500 mg/L.