17.6 Water Conservation Planning & Drought Response
Key Takeaways
- Water Conservation Planning is a named sub-topic in the SWRCB distribution Regulations, Management and Safety category.
- Urban water suppliers must prepare an Urban Water Management Plan every five years and a Water Shortage Contingency Plan with six standard shortage levels.
- California's Making Conservation a California Way of Life framework sets urban water use objectives built from indoor residential, outdoor residential, commercial landscape, and real water loss components.
- Urban retail water suppliers must submit an annual validated water loss audit to the Department of Water Resources.
- Demand hardening means that after years of successful conservation, a utility has less easy savings available in the next drought.
The Planning Requirements
| Document | Who | Frequency | Contents |
|---|---|---|---|
| Urban Water Management Plan (UWMP) | Urban water suppliers (more than 3,000 connections or supplying more than 3,000 AF/year) | Every 5 years | Supply and demand assessment, supply reliability, water quality effects on reliability, demand management measures, recycled water opportunities, climate change considerations |
| Water Shortage Contingency Plan (WSCP) | Same suppliers | With the UWMP, updatable between cycles | Six standard shortage levels, response actions, communication protocols, compliance and enforcement, financial consequences, and an annual water supply and demand assessment |
| Annual Water Supply and Demand Assessment | Same suppliers | Annually by July 1 | Compares projected supply to demand for the coming year under a dry-year scenario and declares the applicable shortage level |
| Validated water loss audit | Urban retail water suppliers | Annually | AWWA methodology, validated, submitted to the Department of Water Resources |
| Agricultural Water Management Plan | Agricultural suppliers above thresholds | Every 5 years | Parallel requirement on the agricultural side |
The six standard shortage levels correspond to shortages of up to 10, 20, 30, 40, and 50 percent, and greater than 50 percent, each with pre-defined response actions. Standardizing the levels statewide was deliberate: during the 2012-2016 drought, every utility had its own stages, and neither the public nor the state could compare them.
Urban Water Use Objectives
California's Making Conservation a California Way of Life framework moved from a single per-capita target to a supplier-specific urban water use objective built by adding up components:
| Component | Basis |
|---|---|
| Indoor residential use | A gallons-per-capita-per-day standard applied to population, stepping down over time |
| Outdoor residential use | Landscape area, evapotranspiration, and an efficiency factor - so a supplier in a hot inland climate with large lots gets a larger budget than a coastal supplier with small lots |
| Commercial, industrial, and institutional (CII) landscape with dedicated irrigation meters | Landscape area and ET |
| Real water loss | A performance standard for leakage |
| Variances and bonus incentives | Adjustments for unique local circumstances and credit for potable reuse |
The objective is a supplier-level budget, not a per-customer mandate. A supplier meets it however it chooses - conservation programs, leak reduction, rate structure, landscape conversion - but the state measures the total.
[!IMPORTANT] Notice that real water loss is a named component of the conservation objective. A gallon saved by fixing a leak counts exactly as much as a gallon saved by a customer taking a shorter shower, and the utility controls it directly. That is why leak detection and meter accuracy programs are conservation programs, not just financial ones, and why the annual validated water loss audit is a state submittal.
Demand Management Measures
| Measure | Type | Notes |
|---|---|---|
| Metering | Structural | Universal metering is the precondition for everything else |
| Water loss control | Structural | Leak detection, meter replacement, pressure management |
| Pressure management | Structural | Leakage rises with pressure; reducing excess pressure reduces both leakage and customer use |
| Conservation pricing | Price | Tiered or budget-based rates, cost-justified under Proposition 218 |
| Landscape ordinances (MWELO) | Regulatory | California's Model Water Efficient Landscape Ordinance sets landscape water budgets for new and rehabilitated landscapes |
| Turf replacement rebates | Incentive | High cost per acre-foot but durable, permanent savings |
| Fixture and appliance rebates and standards | Incentive/regulatory | High-efficiency toilets, clothes washers; state plumbing standards have removed most of the easy savings |
| Irrigation controllers and audits | Incentive | Outdoor use is the largest discretionary component in most California systems |
| CII surveys and process retrofits | Program | Often the best cost per acre-foot for a utility with a large industrial base |
| Public education and school programs | Program | Builds the durable behavior change that carries through the next drought |
| Recycled water and potable reuse | Supply | Technically a supply measure, but it reduces potable demand |
| Waste prohibitions | Regulatory | Runoff onto pavement, hose without a shutoff nozzle, washing down hardscape |
Drought Response Sequencing
- Assess supply against demand through the annual assessment; declare the shortage level.
- Activate the corresponding WSCP stage with its pre-defined actions - this is why the stages are written in advance.
- Communicate clearly and specifically. "Reduce use by 15 percent" is not actionable; "irrigate no more than two days per week before 8 a.m. or after 6 p.m." is.
- Enforce consistently. Warnings, then penalties, applied uniformly. Selective enforcement destroys the program.
- Adjust rates to recover fixed costs, using a drought surcharge or a rate stabilization reserve - and note that this requires Proposition 218 process time, so it must be planned before the drought, not during it.
- Manage the water quality consequences (below).
- Report to the State Water Board as required.
Demand Hardening
After several successful conservation cycles, the easy savings are gone: the toilets are already efficient, the lawns are already gone, the leaks are already found. Demand hardening means the next drought's percentage reduction target is much harder to hit and falls disproportionately on health-and-safety uses. A utility that has already reduced per-capita use to 60 gallons per day cannot cut another 25 percent the way a utility at 150 gallons per day can. This is a real equity issue between suppliers, and it is why the statewide framework shifted from uniform percentage cuts to supplier-specific objectives.
Water Quality Consequences of Falling Demand
Conservation is unambiguously good policy and it creates operational problems the operator must anticipate:
| Consequence | Mechanism | Response |
|---|---|---|
| Higher water age | Lower flow through mains sized for higher demand | Unidirectional flushing, tank turnover management, booster disinfection |
| Loss of disinfectant residual | Decay over longer detention | Same, plus possible residual increase at the entry point |
| Higher disinfection byproducts at the far end | Free chlorine plus precursors plus time | Precursor removal, chloramine conversion, water age reduction |
| Nitrification in chloraminated systems | Warm, stagnant, low-residual conditions | Ratio control, turnover, flushing, breakpoint conversion |
| Sediment accumulation | Velocities fall below the transport threshold | Scheduled flushing at scouring velocity |
| Higher wastewater strength | Same mass of BOD and solids in less water | Process control adjustment; grease and solids issues in collection systems |
| Collection system solids deposition | Lower flows in gravity sewers below self-cleansing velocity | Increased line cleaning, FOG program emphasis, odor and corrosion control from longer detention |
| Revenue shortfall | 75-85 percent of costs are fixed | Rate stabilization reserve, drought surcharge planned in advance |
[!TIP] Explaining the flushing paradox is a real operator communication task. During a drought, customers see hydrants running and conclude the utility is wasting water while asking them to conserve. The honest answer is that flushing at a designed velocity along a designed path, using the minimum volume that will do the job, is what keeps the disinfectant residual in the pipe and the water safe - and that unidirectional flushing was adopted specifically because it uses far less water than the conventional alternative. Say it before the complaint arrives, not after.
How many standard water shortage levels does California's Water Shortage Contingency Plan framework define?
Why is real water loss included as a component of a supplier's urban water use objective under California's conservation framework?
A utility achieves a 25 percent reduction in demand during a drought. What distribution system water quality problem should the operator anticipate?