100+ Free CLWM Practice Questions

Pass your IA Certified Landscape Water Manager exam on the first try — instant access, no signup required.

✓ No registration✓ No credit card✓ No hidden fees✓ Start practicing immediately

Not published Pass Rate

100+ Questions

100% Free

1 / 10

Question 1

Score: 0/0

What does ETo represent in irrigation scheduling?

Reference evapotranspiration for a standardized cool-season grass surface

Effective rainfall minus runoff losses from a site

The maximum applied water allowance set by a local agency

Total infiltration capacity of a soil profile

to track

2026 Statistics

Key Facts: CLWM Exam

150

Exam Questions

Irrigation Association

70%

Passing Score

Irrigation Association

4 hrs

Exam Time Limit

Irrigation Association

$250

Member Exam Fee

Irrigation Association

20 CEUs

Per 2-Year Recertification

Irrigation Association

CLIA/CGIA

Prerequisite Required

Irrigation Association

The CLWM (Certified Landscape Water Manager) is awarded by the Irrigation Association — the leading professional body for irrigation certifications. The exam consists of 150 equally weighted multiple-choice questions over 4 hours, covering 9 domains: water requirements estimation (ETo, MAWA, ETAF), soil-plant-water relationships, water sources, hydraulics, sprinkler layout, scheduling, auditing (DU-LQ), system maintenance, and economics. Candidates must already hold an active CLIA or CGIA credential. The exam fee is $250 for IA members and $495 for non-members.

Sample CLWM Practice Questions

Try these sample questions to test your CLWM exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What does ETo represent in irrigation scheduling?

A.Reference evapotranspiration for a standardized cool-season grass surface

B.Effective rainfall minus runoff losses from a site

C.The maximum applied water allowance set by a local agency

D.Total infiltration capacity of a soil profile

Explanation: ETo (reference evapotranspiration) is the calculated water use of a standardized cool-season grass crop (such as tall fescue or Kentucky bluegrass) under well-watered conditions, used as a baseline for computing crop-specific water demand. Controllers and scheduling software multiply ETo by a crop coefficient (Kc) to estimate actual plant water needs. CIMIS stations and weather-based controllers rely on this value.

2Which formula correctly calculates landscape water requirement (LWR) from ETo?

A.LWR = ETo × Kc × KL ÷ IE

B.LWR = ETo ÷ Kc × precipitation rate

C.LWR = MAWA × KL × IE

D.LWR = ETo × IE ÷ DU

Explanation: Landscape water requirement equals reference ET multiplied by the crop coefficient (Kc, plant-specific water need) and the landscape factor (KL, site adjustment) divided by irrigation efficiency (IE). This yields the gross irrigation volume needed to meet plant demand while accounting for system inefficiency. California's MWELO uses a similar framework for MAWA calculations.

3A landscape has an ETo of 6 in/month, a Kc of 0.5, a KL of 1.0, and an irrigation efficiency of 75%. What is the monthly gross irrigation requirement?

A.4.0 inches

B.3.0 inches

C.2.25 inches

D.8.0 inches

Explanation: Gross irrigation = (ETo × Kc × KL) ÷ IE = (6 × 0.5 × 1.0) ÷ 0.75 = 3.0 ÷ 0.75 = 4.0 inches. The efficiency divisor accounts for sprinkler non-uniformity and other losses, so more water must be applied gross to meet the net plant demand of 3 inches.

4What is MAWA as defined under California's Model Water Efficient Landscape Ordinance (MWELO)?

A.The maximum volume of water that may be applied to a landscape annually, based on a percentage of ETo and landscape area

B.The minimum precipitation rate required from sprinkler heads to meet plant demand

C.The maximum allowable evaporation loss from a storage reservoir

D.A billing-tier threshold set by the local water utility above which surcharge rates apply

Explanation: MAWA (Maximum Applied Water Allowance) under California MWELO is calculated as MAWA = ETo × 0.62 × ETAF × LA, where ETAF is the evapotranspiration adjustment factor (0.55 for most landscapes), LA is landscape area in square feet, and 0.62 converts inches to gallons. It establishes the regulatory maximum annual irrigation volume for a new or rehabilitated landscape.

5The Evapotranspiration Adjustment Factor (ETAF) for a special landscape area under California MWELO is set at what value?

A.1.0

B.0.55

C.0.45

D.0.70

Explanation: Under MWELO, Special Landscape Areas (SLA) — areas irrigated with recycled water, areas used for food production, or recreational turf — are allowed an ETAF of 1.0, meaning 100% of ETo can be applied. Standard landscapes are limited to an ETAF of 0.55 (55% of ETo). The higher SLA allowance recognizes legitimate high-water-use scenarios.

6Which soil texture has the lowest available water-holding capacity per foot of soil depth?

A.Sand

B.Silt loam

C.Clay loam

D.Loam

Explanation: Sandy soils have the lowest available water-holding capacity (AWC), typically 0.5–0.75 in/ft, because large pores drain rapidly by gravity before plants can extract water. Silt loam and loam soils have the highest AWC (~1.5–2.0 in/ft) because their pore-size distribution retains water against gravity while still allowing root extraction. Clay holds water tightly at high tension, reducing plant-available fraction.

7What is the management allowable depletion (MAD) and why is it important for scheduling?

A.The percentage of available soil water that can be depleted before plant stress begins, used to set maximum irrigation intervals

B.The maximum depth of water applied per irrigation event to prevent runoff

C.The difference between field capacity and permanent wilting point in inches per foot

D.A regulatory limit on total applied water set by the water agency

Explanation: MAD is the fraction of plant-available soil water (between field capacity and permanent wilting point) that can be consumed before plants experience water stress. Turf is commonly scheduled at 50% MAD, while woody shrubs may tolerate 60–70%. MAD drives the irrigation interval and net application depth: net depth = AWC × rooting depth × MAD. Exceeding MAD results in stress and yield/quality loss.

8A CLWM measures soil moisture at 42% volumetric water content. Field capacity is 45% and permanent wilting point is 15%. What percentage of available water remains?

A.90%

B.93%

C.80%

D.70%

Explanation: Total available water = FC − PWP = 45 − 15 = 30%. Current available water = current VWC − PWP = 42 − 15 = 27%. Fraction remaining = 27 ÷ 30 = 0.90 = 90%. The soil is at 90% of its available water capacity, meaning only 10% has been depleted — well within a 50% MAD threshold, so irrigation is not yet required.

9Which type of water source typically has the highest salinity concern for landscape irrigation?

A.Recycled (reclaimed) water

B.Potable municipal water

C.Rainwater harvested from a roof

D.Surface water from a pristine mountain reservoir

Explanation: Recycled water (tertiary-treated wastewater effluent) often contains elevated levels of dissolved salts, sodium, boron, and chloride compared to potable supplies because salts concentrate during the treatment process and originate from household and commercial discharge. Landscape managers must monitor EC (electrical conductivity) and SAR (sodium adsorption ratio) to prevent soil sodicity and plant toxicity when using recycled water.

10When using recycled water for landscape irrigation, the sodium adsorption ratio (SAR) is important because high SAR values indicate what risk?

A.Soil structure breakdown due to sodium displacing calcium and magnesium on clay particles

B.Elevated biological oxygen demand causing plant disease

C.Excess nitrogen causing over-stimulation of turf growth

D.Increased water viscosity reducing sprinkler throw radius

Explanation: High SAR in irrigation water causes sodium to displace calcium and magnesium on clay particle exchange sites, causing clay particles to swell and disperse. This destroys soil aggregates, reduces macropore space, and severely reduces infiltration and hydraulic conductivity. Gypsum (calcium sulfate) applications are commonly used to remediate high-SAR soils by restoring calcium dominance.

About the CLWM Exam

Advanced certification for landscape professionals managing water budgets, MAWA compliance, smart controllers, and conservation programs. The CLWM builds on CLIA auditing skills to add economic analysis and agency reporting.

Questions

150 scored questions

Time Limit

4 hours

Passing Score

70%

Exam Fee

$250 (member) / $495 (non-member) (Irrigation Association)

CLWM Exam Content Outline

Equally weighted

Estimating Water Requirements and Use

ETo, crop coefficients, MAWA, ETAF, CIMIS, water budgets, WaterSense controllers

Equally weighted

Soil-Plant-Water Relationships

AWC, field capacity, wilting point, MAD, soil texture, infiltration rate, salinity

Equally weighted

Water Sources

Recycled water, groundwater, EC, SAR, leaching requirement, water quality

Equally weighted

Hydraulics

Friction loss, Hazen-Williams, pressure, elevation effects, PRV, pipe sizing

Equally weighted

Sprinkler Layout and Zoning

Head-to-head coverage, hydrozoning, precipitation rate, nozzle types, drip design

Equally weighted

Scheduling

ET-based scheduling, cycle-and-soak, WBIC, soil moisture controllers, runtime calculation

Equally weighted

Auditing

Catch-can testing, DU-LQ, audit protocol, MWELO compliance, reporting

Equally weighted

System Maintenance

Leak detection, backflow prevention, nozzle replacement, flow sensors, troubleshooting

Equally weighted

Economics

Tiered billing analysis, payback period, ROI, conservation program design, client reporting

How to Pass the CLWM Exam

What You Need to Know

Passing score: 70%
Exam length: 150 questions
Time limit: 4 hours
Exam fee: $250 (member) / $495 (non-member)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CLWM Study Tips from Top Performers

1Master the MAWA formula (ETo × 0.62 × ETAF × LA) and know that standard landscape ETAF = 0.55, Special Landscape Area ETAF = 1.0

2Practice the DU-LQ calculation: average of lowest 25% of catch cans ÷ overall average — understand what it means for scheduling

3Learn the gross runtime formula: net depth ÷ (DU × IE × PR) — both DU and IE must be applied separately

4Understand the difference between WBIC (weather/ET-based) and soil-moisture-based smart controllers and when each is preferred

5Know the leaching fraction formula (LF = ECw ÷ (5ECe − ECw)) and when high-SAR recycled water requires soil amendment with gypsum

6Practice tiered billing calculations: compute each tier block separately, then total — and know how to calculate annual savings from DU improvements

Frequently Asked Questions

What is the CLWM exam format and passing score?

The CLWM exam consists of 150 equally weighted multiple-choice questions administered over 4 hours. A passing score of 70% is required. The exam is administered by the Irrigation Association and covers 9 content domains including water requirements estimation, soil-plant-water relationships, hydraulics, scheduling, auditing, and economics.

Who is eligible to take the CLWM exam?

Candidates must hold a current and active Certified Landscape Irrigation Auditor (CLIA) or Certified Golf Irrigation Auditor (CGIA) credential from the Irrigation Association. Approximately 3 years of irrigation-related work experience is recommended. There is no minimum age or formal education requirement stated by the IA.

How much does the CLWM exam cost in 2026?

The CLWM initial exam fee is $250 for Irrigation Association members and $495 for non-members. Retake fees are $200 (member) and $325 (non-member). Annual renewal is $75 (member) or $125 (non-member) per certification, with an additional $25 fee for each additional IA certification.

What are the recertification requirements for the CLWM?

CLWM holders must earn 20 continuing education units (CEUs) within each two-year recertification cycle, comply with the IA Code of Ethics, and pay the annual renewal fee. CEUs can be earned through IA-approved courses, conferences, webinars, and professional development activities in irrigation and water management.

What is the difference between a CLWM and a CLIA?

The CLIA (Certified Landscape Irrigation Auditor) focuses on field auditing skills — measuring distribution uniformity, performing catch-can tests, and identifying system deficiencies. The CLWM builds on this foundation to encompass water budget development, MAWA calculation, conservation program design, tiered billing analysis, agency reporting, and economic analysis. The CLIA is a prerequisite for the CLWM.

What is MAWA and how is it calculated?

MAWA (Maximum Applied Water Allowance) is the regulatory maximum annual irrigation volume under California's MWELO. It is calculated as: MAWA = ETo × 0.62 × ETAF × Landscape Area (sq ft). The ETAF is 0.55 for standard landscapes and 1.0 for Special Landscape Areas. MAWA compliance is a core CLWM competency.