Spring Sprinkler Startup 2026: Morrison, Littleton & South Denver

When to Turn On: The 2026 Answer

In a normal year, the question is simple: wait until after the last freeze, which in the Morrison–Littleton–Highlands Ranch area falls around May 5 on average. Turn the system on in mid-May, check each zone, adjust your controller, and you're in business.

In 2026, the guidance goes further. Denver Water — which serves Morrison, Littleton, Highlands Ranch, Englewood, and most of the south Denver metro — has been explicit: hold off until mid-to-late May at minimum, and later if possible. The specific guidance from Denver Water's demand planning team is that there is no good reason to run an automatic sprinkler system before May, and every week you delay saves water that the reservoir system genuinely needs. Snowpack finished 2026 as the worst on record since 1941. Reservoirs started spring below their historical average. Every acre-foot counts.

The practical answer for 2026: target May 15 for most lawns in the Morrison–Littleton area. If your grass is still green and the soil is moist (check with the screwdriver test below), push toward June. If you have established trees and shrubs that are visibly stressed — curling leaves, dry soil at the root zone — hand-water those as needed through April. Don't activate the system for them.

Why This Area Starts Later Than You Might Think

Morrison, Littleton, and Highlands Ranch sit between 5,300 and 6,500 feet in elevation depending on the neighborhood. Red Rocks-area neighborhoods on the hogbacks are among the highest. This elevation matters for two reasons. First, freeze dates are later than lower-elevation Denver — the average last freeze for this zone runs through early May, with some years seeing hard freezes into the third week of May. Second, soils in the area tend to be heavy clay or clay-loam (especially in Highlands Ranch), which retains winter moisture significantly longer than sandier soils. Clay soil that froze in January can hold usable moisture into late April even without rain, which is one reason experienced landscape irrigators in this area consistently recommend later startup dates than homeowners expect.

Turning on a system before the soil is actually dry enough to need supplemental water is pure waste. You're running irrigation into soil that doesn't need it, contributing to the surface water runoff and evaporation that does nothing for root health, and drawing from Denver Water's reservoir system during the window when every gallon saved in April reduces summer shortage risk. This is the one spring where delaying startup has a tangible benefit beyond just your water bill.

The Screwdriver Test (Do This First)

Before you even think about activating your system, do this: push a standard flathead screwdriver straight down into your lawn. Push with light hand pressure only — don't force it.

If the screwdriver goes in 6 inches without effort, your soil has moisture at the root zone. Your grass doesn't need supplemental water yet. Check again in a week.

If it stops at 2–3 inches, the upper soil is drying out. You can hand-water stressed areas or newly planted trees. Still no reason to fire up the full system.

If it barely penetrates and the soil feels like compressed dry clay, it's time to start thinking about system activation — especially if you're past May 1 and nighttime lows are consistently above 35 degrees.

Stage 1 Rules Once You Do Start

Once you activate your system, Denver Water's Stage 1 restrictions apply. You'll need to program your controller accordingly:

Two days per week, maximum. Even-numbered addresses: Sundays and Thursdays. Odd-numbered addresses: Wednesdays and Saturdays. Check the last digit of your house number — that's what determines your days.

No watering between 10 a.m. and 6 p.m. This is a year-round rule, not just a drought rule. Program your controller to run early morning (4–8 a.m. is ideal) or after 6 p.m. Morning is strongly preferred — blades dry before evening, which prevents the fungal diseases that become more common when grass stays wet overnight.

Trees, shrubs, perennials, and vegetables can be hand-watered any day — including off your assigned lawn days — as long as you're using a handheld hose or drip irrigation and staying within the 6 p.m.–10 a.m. window. This is the Stage 1 rule; it may change if drought escalates to Stage 2.

Repair leaks within 10 days. This is a Denver Water requirement year-round, but especially important now. A single zone with a cracked head or split lateral can lose thousands of gallons per month. Walk every zone on your first startup and flag anything that needs repair before you leave it on a schedule.

The Startup Process: Step by Step

Step 1: Locate and close your backflow preventer ports. Your backflow preventer is usually on the exterior of the house — often near the hose bib. Before you open the main valve, look for the test ports (the small side ports with caps). Using a flathead screwdriver, turn each port a quarter-turn so it's perpendicular to the pipe (closed position). If you open the main valve with these ports open, water will gush out of them.

Step 2: Open the main isolation valve slowly. Your main irrigation shutoff is usually either in the basement (a ball valve on the main supply line) or at an outdoor meter box. Open it slowly — quarter-turn increments with a pause in between. Opening too fast creates a water hammer effect that can crack fittings and damage valves. Take two to three minutes to fully open it.

Step 3: Open the backflow preventer ball valves. Once main pressure is restored, open the ball valves on the backflow preventer by turning handles parallel to the pipe. This allows water into the irrigation supply line.

Step 4: Run each zone manually and walk it. Don't just set a schedule and go inside. Run each zone one at a time from the controller and physically walk the zone while it runs. You're looking for: heads that aren't popping up fully (clogged or damaged), spray patterns hitting concrete or sidewalks (misaligned or wrong nozzle), wet spots in the lawn before the zone runs (broken lateral line with standing water), pressure that seems lower than usual in a zone (broken head, split pipe), and any heads tilted from freeze-thaw or mower damage over winter.

Step 5: Check your drip zones separately. If you have drip irrigation on trees, shrubs, or a garden, run those zones and walk the line. Drip emitters clog over winter and rodents sometimes chew through drip tubing. A clogged or broken drip zone wastes water invisibly — the controller shows it running, but nothing's getting delivered.

Step 6: Program your controller for Stage 1 compliance. Set your assigned days (even or odd address), time the start before 10 a.m., and set run times appropriate for May — not July. May run times should be roughly 25–30% shorter than your peak summer setting. The lawn doesn't need summer volumes yet; the goal is to wet soil 4–6 inches deep two mornings per week and let it dry between sessions.

Step 7: Note anything that needs repair. Make a list on your first walkthrough and get repairs scheduled before the system runs unsupervised. Irrigation repair companies book up fast once the season starts — a broken head you notice in May might not get fixed until July if you wait.

Should You Hire Someone or DIY?

In a drought year when every gallon matters, having a professional irrigation technician do your startup is genuinely worth it if your system has had any issues in past seasons. A professional will test operating pressure at each zone (which reveals problems DIY walkthroughs miss), adjust or replace worn nozzles for proper coverage, check the controller's seasonal adjustment settings, and catch slow leaks that aren't visible from the surface.

If your system ran without issues last fall and was properly winterized (blown out), a DIY startup following the steps above is completely reasonable. The key thing either way: don't skip the zone walkthrough. Systems that ran fine in October can have freeze damage that only shows under pressure in spring.

Morrison, Littleton, and Highlands Ranch have a solid base of local irrigation companies who specialize in this area. Booking before May 1 gets you better availability. After May 15, companies are often weeks out.