With water bans now in effect across parts of Iowa due to elevated nitrate levels in our drinking water, how we care for our lawns and landscapes has taken on new urgency. While residential and commercial irrigation contributes to water use, it’s important to clarify: the primary source of nitrate contamination is agricultural fertilizers—not lawn fertilizers.
That said, how we manage our turf—especially our watering practices—can significantly impact both lawn health and the pressure placed on already-strained water treatment systems.
Understanding the Water Ban: Where Are the Nitrates Coming From?
The Des Moines and Raccoon Rivers, which supply drinking water to much of central Iowa, are increasingly polluted with nitrates—primarily from agricultural runoff in the spring and early summer, when synthetic fertilizers are applied in large volumes.
While lawn fertilizers play only a minor role in nitrate levels, excessive lawn watering can still contribute to nutrient runoff. Overwatering washes fertilizers and nutrients off lawns and into storm drains or groundwater, placing further burden on our municipal systems.
According to the Iowa State University Extension, treating high-nitrate water is expensive and resource-intensive. The best solution? Prevent the problem at the source—starting with smarter irrigation.
What We’ve Learned from the Field
As irrigation professionals, it’s been eye-opening to see how many residential systems are set to overwater by default. When the watering ban was enacted and we assisted with shutting down residential systems, we found many were programmed to run five days a week—even during periods of moderate rainfall and average temperatures.
Even now, with the heat and humidity of summer in full swing, a five-day watering schedule would still be excessive under normal conditions. This is a great moment to revisit and reinforce smart watering practices so homeowners are prepared to manage their systems wisely when the ban is lifted.
Here’s what we recommend:
- Spring and fall: Water twice a week using deep-watering cycles or cycle/soak features.
- Typical summer weather: Increase by one additional day and reassess before adding more. Many controllers offer a Seasonal Adjust feature—changing this from 90% to 110% (for example) may be all that’s needed to accommodate rising temps, without changing days per week.
- Hot, dry extremes: A five-day schedule should be reserved for extended periods (e.g., a three-week stretch of 90°F+ with no rainfall).
- Weekly rainfall of 0.5” or more: Adjust watering accordingly—lawns typically only need 1 inch of water per week under normal conditions.
- Extended or heavy rain: Turn off systems entirely or use a rain delay setting to avoid unnecessary watering.
Use a basic rain gauge or consider upgrading to a smart controller that receives live weather updates to optimize your watering decisions.
Why Overwatering Hurts More Than It Helps
Contrary to common belief, more water doesn’t always mean a healthier or greener lawn. In fact, overwatering often creates more problems than it solves:
- Nutrients are wasted. Saturated roots can’t absorb water properly—so nutrients are flushed away before the plant can use them.
- Roots stay shallow. Overwatering discourages grass from growing deeper roots, essentially training the turf to be lazy and dependent on surface water.
- Soil compacts. Consistently wet soil reduces oxygen availability, which is essential for root health.
- Treatment systems are overwhelmed. More runoff means more contaminants entering the water supply, increasing the cost and complexity of treatment.
A frequently watered lawn isn’t necessarily a healthy lawn—especially if it can’t survive a few dry days without showing stress.
Water Less, Grow More: The Science Behind Strong Turf
Research from the University of Minnesota and Michigan State University Turfgrass Science programs confirms what professionals already know: deeper, less frequent watering results in stronger turf. When grass is encouraged to search deeper for water, its root system becomes more resilient and drought-tolerant.
The benefits of deep watering include:
- Increased drought resistance
- Better nutrient absorption
- Improved soil structure and erosion control
The ISU Extension recommends applying no more than 1 inch of water per week, including rainfall. That’s all it takes to keep the turf’s crown hydrated and the lawn healthy.
Turf Dormancy: A Natural, Healthy Process
In hot, dry conditions, cool-season grasses such as Kentucky bluegrass and perennial ryegrass naturally enter a temporary state of dormancy. Grass may appear tan or straw-colored, but this is a natural survival response—not a sign of damage.
As Jake Newman, RJ’s Turf Services Production Manager and President of the Iowa Professional Lawn Care Association (IPLCA), explains:
“During times of water restrictions or drought stress, turfgrass will naturally slow its growth and enter a dormancy phase. This is a built-in survival response—not a sign of death or decline. The key is to irrigate just enough to keep the crown hydrated. Overwatering not only undermines this natural process but adds unnecessary pressure to local water systems already struggling with nitrate contamination.”
Once temperatures drop and rainfall returns, dormant lawns typically recover quickly—with no need for expensive reseeding or sodding.
The Power of Smart Irrigation
Modern smart irrigation systems are designed to make watering more precise and less wasteful. Using weather data, rain sensors, sunlight monitors, and soil moisture probes, these systems tailor watering schedules to actual conditions on your property.
Studies from Purdue University Turf Science show that switching to smart irrigation can reduce outdoor water use by 30–50% without sacrificing plant health.
Dripline for Beds and Borders
For mulched beds and foundation plantings, drip irrigation is the most efficient method available. It delivers low-pressure water directly to plant root zones, significantly reducing evaporation and runoff.
Benefits include:
- Healthier, less stressed ornamental plants
- Lower risk of fungal disease
- Reduced weed pressure
- Minimal water waste
Drip systems are especially effective during droughts and water restrictions, helping landscapes thrive with less input.
Mow Smarter, Not Shorter
One of the most overlooked practices in lawn care is proper mowing height. Cutting your grass too short may reduce mowing frequency, but it weakens your turf and increases water needs.
We recommend keeping mower decks set to at least 3.75 inches.
Here’s why that matters:
- Taller grass holds more moisture and shades the soil, protecting it from sun and wind.
- The deeper green portion of the blade supports photosynthesis and root zone cooling.
- Short-cut turf browns more easily, requiring more water to maintain appearance.
Raising your mower height is one of the simplest ways to improve your lawn’s resilience—and it doesn’t cost a thing.
Smarter Irrigation Starts with You
While agriculture is the leading source of nitrate contamination in Iowa’s water, residential and commercial landscapes still play an important role in conservation. By adopting smarter watering strategies, mowing with intention, and embracing seasonal dormancy, we can all contribute to healthier lawns and a healthier Iowa.
At RJ Lawn & Landscape, we’re proud to lead by example—combining expert knowledge, real-world experience, and peer-reviewed science to help you make the best decisions for your lawn, your community, and the environment.
