New Waste Generation Studies, Annual Generation-Based Diversion Rates, and New Base Years Prior to 2007

Note: This page contains historical information from CalRecycle’s statewide goal measurement prior to 2007 that estimated a diversion percentage. For 2007 and subsequent years, CalRecycle compares reported disposal tons to population to calculate per capita disposal expressed in pounds/person/day. This new goal measurement system is described in CalRecycle’s Goal Measurement: 2007 and Later web page. With the implementation of this measurement system, CalRecycle will only accept new base year studies commenced prior to June 30, 2008. A jurisdiction may conduct a generation study for internal review purposes; however, CalRecycle will not review it for compliance determination.


The original solid waste generation studies quantified the amounts and identified the types of solid waste disposed and diverted from each jurisdiction (incorporated city, unincorporated county, or regional agency) and established its base year. These studies helped jurisdictions understand their waste streams and implement cost-effective waste diversion programs. Most jurisdictions have 1989-1991 original solid waste generation studies. Data errors in a jurisdiction’s original disposal and diversion estimates can make it difficult to accurately measure progress toward achieving diversion requirements.

Establishing a new base year is one solution to resolving data accuracy problems. The first step in establishing a new base year is a new generation study. A generation study consists of disposal amounts from disposal reports and diversion amounts from a new diversion study. A new generation study compiles the “best available information” to accurately measure a jurisdiction’s diversion efforts. More than half of jurisdictions have replaced the original base years with a new base year.


    • “Base-year generation tonnage” means the most recent CalRecycle-approved waste generation amount (disposal + diversion) for any jurisdiction.
    • “New generation study” means a study conducted by a jurisdiction that quantifies the amounts of solid waste disposed and identifies the types and amounts diverted from the jurisdiction in a calendar year.

New Generation Study (Disposal + Diversion)

A new generation study is used to obtain a generation-based diversion rate and/or a new base year for disposal-based diversion rate measurement.


    • A new generation study helps a jurisdiction understand its waste stream and divert more solid waste from disposal.
    • A generation study can be done each year to determine a diversion rate. A jurisdiction may consider doing a generation study when an unusual event occurs, when more detailed data is needed, or when the existing base year is outdated.
    • A new generation study helps jurisdictions successfully select, plan, and implement cost-effective diversion programs. It may also be used to establish a new base year for diversion rate estimates.


    • A jurisdiction must report a diversion rate each year. A jurisdiction may estimate its diversion rate using the adjustment method or doing a new generation study.
    • A jurisdiction should consider why it is gathering data and how it will use the data, keeping in mind that data gathered for one purpose may not be useful for other purposes.
    • Not all jurisdictions are alike. They may have different waste streams, encounter different challenges, and have different data needs.
    • A new generation study should only include disposal and diversion that occurs in a calendar year and originates within the jurisdiction’s borders.
    • The information in a jurisdiction’s generation study must be representative, accurate, and account for seasonal variation.
    • Disposal information must include all sources of solid waste in a jurisdiction, including residential, commercial, industrial, self-haul, and any other sources (military, marine, parks, etc.) disposed at Board-permitted landfills, transformation facilities, or exported. As of January 1, 1995, jurisdictions are required to use the disposal reporting system to determine annual disposal tonnage.
    • Diversion claimed must be identified in a new diversion study. The jurisdiction must identify programs that divert the solid waste. This includes public, private, and nonprofit programs; programs for residential, commercial, and industrial sources; and source reduction, recycling, and composting programs.

Generation Study—For A Generation-Based Diversion Rate


    • A generation study can be used to obtain a generation-based diversion rate for the year studied.
    • Major, unusual events in the study year should be described, including natural or man-made disasters, special events, and other one-time impacts on the waste generation amount.
    • CalRecycle staff reviews each jurisdiction generation study, makes necessary corrections, and presents the study to CalRecycle for consideration as part of a jurisdiction review.


    • A generation-based diversion rate may be submitted in an annual report to CalRecycle.

Generation Study—For A New Base Year


    • A generation study can be used to obtain a new base year for disposal-based diversion rate estimates.
    • A jurisdiction may want to establish a new base year if the old base year contains large errors in the disposal or diversion amounts, or no longer reflects current waste generation patterns.
    • Establishing a new base year may be necessary if CalRecycle or the jurisdiction determines the base year generation tonnage estimate is inaccurate.


    • To establish a new base year, a jurisdiction requests CalRecycle to approve its generation study and make it the base year for future diversion rate estimates.
    • A jurisdiction with a base year that is more than three years old may need to establish a new base year because CalRecycle does not allow corrections to base years that are more than three calendar years old.
    • At any time, a jurisdiction may submit a request to CalRecycle to replace its existing CalRecycle-approved base year with a more current base year. A jurisdiction may include a new base year request in its annual report to CalRecycle.

Legislation, Statutes, and Regulations


Chapter 1095, Statutes of 1989 (Sher, AB 939)

Statute: Public Resources Code (PRC) Sections

PRC 41030-41033, City Source Reduction Recycling Element Waste Characterization Component
PRC 41330-41333, County Source Reduction Recycling Element Waste Characterization Component
PRC 41780, Waste Diversion Planning Requirements


Title 14, California Code of Regulations (14 CCR), Chapter 9, Article 6.1, Solid Waste Generation Studies

For more information contact: Local Assistance & Market Development,