project profiles

Cemented stormwater canal


LWA stormwater management activities include NPDES permitting assistance, development and implementation of programs and guidance manuals for best management practices (BMPs), assessing stormwater quality monitoring data for regulatory compliance, establishing and conducting stormwater monitoring programs, and developing legal authority to establish stormwater management programs.
In addition, LWA has modeled stormwater discharges with EPA’s SWMM and HSPF numerical models and using multivariate statistical regression, Monte Carlo, and modified “rational method” techniques.

Sacramento Stormwater Quality Partnership Monitoring and Regulatory Support

LWA has conducted stormwater monitoring activities and regulatory assistance tasks for the Sacramento area since 1992, for the municipal partner agencies now known as the Sacramento Stormwater Quality Partnership (SSQP). In 1994 LWA became the prime contractor responsible for sample collection, identifying and selecting storms for monitoring, and delivery of samples. Our work relies on extensive use of automated sampling apparatus, sensor technologies, clean sampling techniques, and quality control activities and includes field crew mobilization, quality assurance protocols, documentation, and liaison with the analytical laboratories. LWA provides technical assistance in support of NPDES permit requirements including permit reissuance and participation in stakeholder efforts. Major project achievements include:

  • Analysis of variance assessment approach for trend analysis, power analysis, and load modeling for permitted area (1992, 1996, 2005, 2009, and 2013).
  • Urban runoff storm composite samples and receiving water sample collection to comply with NPDES permit requirements and support management activities.
  • Database automation and data access tools for collaboration efficiencies
  • Delta Methylmercury TMDL Control Study Work Plan, loading assessments, and Watershed Treatment Model implementation
  • Target pollutant evaluation and prioritization and updates
  • Key participation in regional and stakeholder groups such as the Delta Regional Monitoring Program, the Central Valley Drinking Water Policy Workgroup, TMDL stakeholder groups, and others.
  • Performance evaluations of best management practices and low impact development.
  • Preparation of notices of water quality exceedance (NWQE), as required in the Partnership’s NPDES permit.
  • Preparation of year-end report of water quality exceedance (RWQE) for those constituents where urban runoff are causing or contributing to the receiving water water quality objective.
County of Orange Stormwater Management Program Regulatory and Implementation Assistance

Since 2002, LWA has assisted the County of Orange, as Principal Permittee, and on behalf of the 34 Orange County municipal Permittees, with the development and implementation of the area-wide Stormwater program and Drainage Area Management Plan as well as the renewals of their NPDES stormwater permit.

Our assistance includes:

  • Regulatory assistance during the renewal of the stormwater permits, including review of draft orders, development of written comments, development of alternative permit language, and/or development and provision of testimony to City councils, County Board of Supervisors, and/or Regional Water Quality Control Board members
  • Development of technical and policy documents including the Drainage Area Management Plan (DAMP), Local Implementation Plan model, Reports of Waste Discharge, and Annual Reports (including program effectiveness assessments)
  • Implementation of the Existing Development (Industrial/Commercial and Residential) and Illegal Discharges/Illicit Connections Programs including functional updates of the programs,, development of tools/guidance materials, and development and implementation of introductory and advanced training modules, which have been provided to several hundred stormwater program managers, industrial/commercial inspectors, water pollution responders, fire department personnel and restaurant inspectors
  • Implementation of the sanitary sewer overflow (SSO) response pilot program including coordination of desk-top and field-based exercises, identification of high priority areas for implementation, development of annual reports, and participation in stakeholder meetings
  • Development of a formal stormwater training program including a overarching program framework, identification of key target audiences and core competencies, functional updates to existing training modules, and coordination with other regional training programs and stakeholders including Regional Water Quality Control Board staff
  • Development of field-based procedures for responding and reporting on urban discharges that exceed dry weather numeric action levels (pursuant to the San Diego Regional Permit).
City of Los Angeles Bureau of Sanitation

LWA has provided the City of Los Angeles (City) Bureau of Sanitation (LASAN) with regulatory consulting services since the late 1990s. LWA has supported the City develop effective policy and technical solutions for their wastewater and stormwater programs, including the following stormwater program support:

  • Reviewed, commented, and supported negotiations on the following TMDLs developed by the State and/or USEPA: Machado Lake Toxics TMDL, Santa Monica Bay Marine Debris TMDL, and Los Angeles Area Lakes TMDLs.
  • Developed alternative approaches to for Dominguez Channel and LA/Long Beach Harbors Toxics TMDLs. Identified solutions to address LASAN concerns with the TMDL that were acceptable to the State and resulted in revisions to the TMDL that support development of additional science for the TMDL reopener while maintaining compliance with interim requirements. Supported negotiations with the State, USEPA, and other dischargers and provided support developing testimony for the adoption hearing.
  • Supported LASAN during negotiations with the State on revisions to the Santa Monica Bay Dry and Wet Weather Bacteria TMDLs and the Marina del Rey Bacteria TMDL. Conducted analysis of bacteria data, proposed updates for consistency with the latest available science, reviewed and commented on draft TMDL documents, and provided support developing testimony for the State adoption hearing.
  • Developed strategy and conducted technical analysis in support of TMDL revisions for the Ballona Creek Toxics, Metals, and Bacteria TMDLs. Analysis included evaluating compliance with current TMDL targets, proposing revisions to targets based on the latest available data, proposed updates to compliance language to allow for multiple methods for compliance, and developed information to support the extension of the Toxics TMDL compliance deadline. Supported negotiations with the State, including developing testimony for the State adoption hearing.
  • Managed and conducted monitoring to evaluate bacteria loading in three watersheds from urban runoff. The monitoring included up to three teams deploying during dry weather to monitor all flowing outfalls for flow rates and coli concentrations to determine loadings to support implementation planning.
  • During the development and adoption of the 2012 Los Angeles County MS4 Permit, LWA provided regulatory support to the majority of the Permittees in the County via contracts with the City of Los Angeles, Los Angeles Permit Group, and County of Los Angeles. LWA participated from the beginning of the adoption process and developed several approaches that were utilized by the Regional Board as the basis for key permit sections, including (1) the watershed-based permit structure, (2) BMP-based compliance options for interim TMDL wasteload allocations, (3) utilizing the Watershed Management Programs as a compliance option for the Receiving Water Limitations provisions, and (4) the development of the Watershed Management Program concept that incorporates all elements of the Permit, but allows Permittees to focus efforts on identified water quality issues in the watershed by prioritizing and modifying certain Permit requirements. LWA identified modifications to the current stormwater management programs, developed the suggested framework and content for the watershed plans, and provided justification to modify the previous permit structure to accommodate the proposed watershed based approach via modifiable minimum control measures and monitoring requirements. LWA’s development of materials demonstrating the proof of concepts and incorporating the range of Permittee perspectives enabled the Permittees and RWQCB to find common ground on difficult issues.


Arial photo of farmland


LWA in the News

LWA services related to groundwater include:

  • Groundwater Sustainability Plan (GSP) Development and Implementation (LWA has developed 5 approved GSPs)
  • Sustainable Groundwater Management Act (SGMA) Planning and Development
  • Salt and Nutrient Management Plans (SNMP)
  • Groundwater Monitoring Plan Development, Data Management and Analysis
  • Groundwater Resource Evaluation
  • Integrated Groundwater Flow and Transport Modeling
  • Aquifer Recharge Development and Water Banking Planning
  • Water Balance/Budget Analysis
  • Well Monitoring
  • Technical Report Assessment and Preparation
LWA assists our clients under California’s evolving groundwater regulations. Our long-term experience managing surface water, stormwater and wastewater, combined with our expertise in groundwater resource evaluation, allows our team to take a coordinated approach to integrated water management assistance.

Starting in 2018, LWA has led a consultant team to work with the Ukiah Valley Basin Groundwater Sustainability Agency (UVBGSA) in developing a GSP (UVBGSP) for the Ukiah Valley groundwater basin. The LWA Team is assisting UVBGSA with evaluating the most cost-and resource-effective plan toward groundwater sustainability, in compliance with SGMA. Through extensive communication with UVBGSA members and Ukiah Valley stakeholders, LWA ensures that groundwater management remains at the local level, while assisting the client and stakeholders to sustainably manage their groundwater resources. The LWA team is developing a GSFLOW model and also has been coordinating with the State Board to use the same numerical platform for both the GSP and the instream flow evaluation. Sharing of information is underway and once developed the two models will be capable of being fully integrated.

LWA’s efforts include program management and client coordination; facilitation and outreach; analysis of existing data and evaluation of enhancements to the data collection network; supporting the GSA with  application for Technical Support Services at DWR; evaluation and improvement of existing groundwater numerical flow model and water budget; coordination with neighboring subbasins and parallel efforts (USGS and SWRCB); development of sustainability goals, measurable objectives and management scenarios; development of UVBGSP implementation plan; and preparation of draft and final UVBGSP.

Map of the Ukiah Valley showing well locations and geologic features.

In January 2020, LWA began leading a consultant team to work with the Sacramento Central Groundwater Authority (SCGA) in developing a Groundwater Sustainability Plan (GSP) for the South American Subbasin (Subbasin). The LWA Team assisted SCGA in completing the most cost- and resource-effective plan toward groundwater sustainability in compliance with the 2014 California Sustainable Groundwater Management Act (SGMA).

  •  The LWA Team is preparing quarterly progress and accountability reports, Project and Grant Completion Reports, QA/QC Plan for conducting the work, and assisting SCGA and the Department of Water Resources (DWR).
  • Stakeholder Communication and Engagement
  • Develop Sustainable Management Criteria
  • Develop Projects and Management Actions:
  • Improvements to the Monitoring Network
  • Cost Analysis and Rate Study
  • Development of the GSP
  • Development of Annual Report Template
  • Model Development Assistance

The Westside Sacramento Integrated Regional Water Management (IRWM) program selected the Dunnigan project (project) to receive the IRWM Funding Area set-aside funds from the Department of Water Resources Urban and Multi-benefit Drought Relief Program. The project utilizes Section 215 water when available, excess contract water from Dunnigan Water District (DWD) and purchased surface water from senior water rights holders until a permanent winter water right is obtained. Surface water will be diverted from the Tehama-Colusa Canal (TCC) into Buckeye, Dunnigan, and Bird Creeks (i.e., ephemeral streams) and onto approximately 200 acres of farmland enrolled in The Nature Conservancy’s multi-benefit recharge program. The project will improve water supply reliability for the disadvantaged community of Dunnigan; provide habitat for migratory waterfowl; enhance groundwater-dependent ecosystems; and reduce the risk of subsidence damaging nearby infrastructure, including the TCC and Interstate 5.

Tasks include:

  • Stakeholder coordination, including with the Yolo Subbasin Groundwater Agency, private landowners, NGOs, Westside Sacramento IWRM, and DWR;
  • Implementing a groundwater recharge project that can be implemented long-term and expanded into other areas to stabilize groundwater levels and storage volumes, prevent stream depletions, and protect groundwater-dependent ecosystems;
  • Assessing project benefits through water budgets, hydrologic modeling, and isotope studies;
  • Site selection and characterization of the recharge site locations;
  • Regulatory permitting assistance;
  • Overseeing groundwater monitoring network installation and ongoing monitoring implementation; and
  • Identifying infrastructure upgrades or retrofits to improve recharge capacity utilizing DWD’s conveyance and drainage systems.

Starting in 2018, LWA has led a consultant team to work with the Siskiyou County Flood Control and Water Conservation District (District) in developing three separate GSPs for the Shasta, Scott and Butte Valley groundwater basins. To comply with SGMA, the LWA Team is assisting the District to assess the most cost-and resource-effective groundwater sustainability plan. Through extensive communication with District members and Shasta, Scott and Butte Valley stakeholders, LWA ensures that groundwater management remains at the local level, while assisting the client and stakeholders to sustainably manage their groundwater resources. LWA’s efforts in support of the District include:  

  • Public Outreach and Engagement
  • Data Collection, Development, and Management
  • Water Budget Development
  • Development of Sustainability Criteria
  • Monitoring Programs, Protocols and Networks
  • Writing and Reporting of Documents
Omochumne-Hartnel Water District – Basin Boundary Modification Request —SGMA Assistance

  • Completion of SGMA basin boundary modification request to the Department of Water Resources on behalf of Omochumne-Hartnell Water District.
  • Collaboration with small water district and local stakeholders.
  • Analysis of a complex groundwater system that included the integration of geophysical data, water quality information, hydrogeologic findings, precipitation records, and stream flow data under a tight time frame.
  • Incorporation of jurisdictional and scientific reasoning to support client needs.
  • Submission of information as required under SGMA regulations on compressed schedule.
Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS)

Beginning in 2009 and continuing through 2016, LWA has led a team of consultants performing a variety of technical services in support of the development of a Salt and Nitrate Management Plan for the Central Valley (CV-SNMP).   The CV-SNMP has been developed through a multi-year stakeholder process, Central Valley Salinity Alternatives for Long-Term Sustainability (CV-SALTS).  The purpose of the CV-SALTS process has been to bring stakeholders together to develop information, strategies and suggested policies to address long term groundwater quality issues associated with nitrates and salts in the Central Valley of California.  The CV-SNMP will be used as the basis for a Basin Plan amendment that will restore drinking water supplies to communities impacted by elevated nitrates, control salt and nitrate degradation of groundwater basins through implementation of major treatment and transport projects, and improve groundwater quality to meet salt and nitrate water quality objectives, where reasonable and feasible.

LWA has successfully developed the following documents which are essential components of the CV-SNMP, working collaboratively with the CV-SALTS stakeholder group.

1) CV-SALTS Initial Conceptual Model & Geographic Information Services (Phase I) – California Central Valley

  • Establishment of salt and nitrate surface water and groundwater budgets for California’s Central Valley
  • Assessment of the long-term groundwater quality conditions in the Central Valley (20-year time period from 1983-2003)

2) CV-SALTS Phase II Conceptual Model – California Central Valley

  • Groundwater data refinements and updates
  • Development of a Management Zone archetype analysis for Alta Irrigation District to test the application of selected policies, data analysis methods, and salt and nitrate management approaches that are being considered by CV-SALTS
  • Preparation of the Preliminary Draft Central Valley SNMP


  • Preparation of Economic Analysis of proposed management and policy alternatives under CV-SNMP. Provided cost analysis of nitrate and salt management alternatives in Alta Irrigation District and the Central Valley.
  • Preparation of Antidegradation Analysis for salt and nitrate policy alternatives under CV-SNMP, working closely with stakeholder group, Central Valley Salinity Coalition and the Central Valley Regional Water Board.

4) Tulare Lakebed MUN and AGR beneficial use de-designation

  • Prepared CEQA scoping documentation, technical and policy analysis, and draft staff report to support a Basin Plan amendment to de-designate MUN and AGR uses in the historic Tulare Lakebed area in the lower San Joaquin Valley.

Task 3, water volume data, salt data, and nitrate data flow down to Task 5, methodology. Task 4, Establish I.A.Z.s flows to Task 5. Task 5, methodology flows to either Task 6, I.A.Z. analysis of CV floor water, salt, and nitrate balances, or to Task 7, high resolution analysis for water, salt and nitrate balances for prototype areas of Stanislaus/Merced and Kings.

Wastewater treatment plant


LWA offers a full range of wastewater-related services:

  • Influent/Effluent Monitoring
  • Dilution Studies
  • Source Control Studies
  • Local Limits Development
  • Pretreatment Program Development/Assessment
  • Pollution Prevention Program Development/Assessment
  • Facilities Master Planning
  • Recycled Water Program Development
LWA works with wastewater agencies throughout California to implement permit requirements, assess and improve existing programs, and develop new approaches for wastewater handling. LWA’s in-depth knowledge of state and federal regulations allows us to provide assistance with complicated program requirements such as local limits development, pretreatment programs, dilution studies, and pollution prevention programs. Our ability to keep ahead of the curve on regulatory requirements provides valuable perspective in the preparation of facilities’ master plans.

Sacramento Regional County Sanitation District (Regional San) NPDES Permit and Regulatory Assistance Services

LWA has provided a variety of regulatory consulting services to Regional San since 1990. Our work has included assistance to Regional San on the following:

  • NPDES Permit renewals for Regional San’s regional wastewater treatment plant including preparation of data compilation and data quality analyses, reasonable potential analyses, effluent limit derivations, and a variety of special studies, including Anti-Degradation Analyses, Mixing zone studies, and modeling to support dissolved oxygen impact analysis.
  • Central Valley Drinking Water Policy development, including creation of work plan, stakeholder work group support, technical evaluations and Basin Plan amendment development.
  • Delta Mercury TMDL development and stakeholder group support
  • Delta Nutrient Management Strategy development and stakeholder process support.
  • Bay Delta Conservation Plan, Delta Plan, Delta Science Plan reviews and comment preparation.
  • A dynamic water quality model for use in calculation of Water Quality Based Effluent Limits, in collaboration with Flow Science, Inc.
  • Regulatory advice and advocacy on behalf of Regional San on various water quality policies, regulations and rulemakings by USEPA, SWRCB and the Central Valley Regional Water Board.
  • Sacramento Coordinated Monitoring Program development, design, implementation, data analysis and reporting.
  • Sacramento River Watershed Program design, stakeholder process support, data analysis and reporting.
  • Mercury offset program feasibility studies, field investigations and stakeholder process.
  • Water quality impact analyses in support of environmental impact report and CEQA documentation for Regional San’s new EchoWater project, an advanced wastewater treatment facility featuring new nitrification, denitrification and filtration facilities.

For 25 years, LWA has assisted Regional San in support of sound regulatory policy, effective stakeholder involvement, and improved scientific understanding of the Sacramento River watershed and the Sacramento-San Joaquin Delta.

Victor Valley Wastewater Reclamation Authority Regulatory Assistance

LWA, in collaboration with Luhdorff & Scalmanini Consulting Engineers (LSCE), provides assistance to VVWRA to negotiate and implement several critical sets of agency and government requirements, including:

  • NPDES permit for discharge to the Mojave River
  • Waste Discharge Requirements for discharge to percolation ponds at its main wastewater reclamation facility and proposed sub-regional facilities
  • Master Reclamation Requirements for recycled water from the main and s-ubregional facilities
  • Permit requirements and Pretreatment Program elements and preparation of annual reports required by its WDRs

Permit renewal efforts included preparation and submittal of Reports of Waste Discharge, Title 27 exemption analysis, capacity analyses, Title 22 Engineering reports and anti-degradation analyses. Impacts to groundwater were assessed using mixing models and review of groundwater well data with an emphasis on analysis of Total Dissolved Solids and nitrogen compounds. LWA and LSCE documented decreasing trends in levels of nitrogen compounds in local groundwater as treatment plant effluent quality has improved due to plant upgrades. In addition, our analysis demonstrated that all groundwater impacts are localized due to natural barriers (Shay Road fault) that prevents flow of groundwater beyond a certain point in the basin. In addition, LWA supported VVWRA in meetings with Lahontan Regional Board staff to negotiate various aspects of each permit.

LWA also assisted the VVWRA in responding to a sewer line breach in the Mojave River that occurred during heavy storms in December 2010 with reports and documentation required by Lahontan Regional Board, California Department of Fish and Game and other regulatory agencies. In addition, LWA contacted well owners who may have been impacted by the spill to assist with sampling the wells and providing monitoring results.

Sonoma County Water Agency/Sonoma Valley County Sanitation District

LWA has assisted the Sonoma Valley County Sanitation District (District) with NPDES and recycled water permit activities since 2000.

The Sonoma Valley Wastewater Treatment Plant discharges treated effluent to a slough during high inflow events, produces disinfected tertiary recycled water for agricultural irrigation, and beneficially reuses effluent for habitat management in cooperation with the California Department of Fish and Wildlife.

LWA supported Regional San during the 2002, 2008, and 2014 NPDES permit reissuance activities. The work involved negotiating operational requirements, compiling effluent and receiving water quality data, determining Reasonable Potential, checking effluent limit calculations, assessing compliance feasibilty, and designing an appropriate compliance monitoring program. During the NPDES permit terms, LWA developed site-specific metals translators, implemented studies to determine effluent copper and cyanide impacts, provided updates to Regional San on changes to regulatory policies, and participated in the San Francisco Bay Nutrient Strategy Stakeholder Advisory Group.

LWA prepared Regional San’s current recycled water program and obtained permit coverage under General Water Reuse Order No. R2-1996-011. To receive program approval, LWA updated the CCR Title 22 Engineering Report (when Regional San upgraded from “disinfected secondary-23 recycled water” to “disinfected tertiary recycled water”), verified minimum modal contact time, prepared materials (i.e., permits, self-monitoring reports, site inspection reports, user guidelines), and developed a cross-connection control program.

City of Los Angeles Bureau of Sanitation

LWA has provided the City of Los Angeles (City) Bureau of Sanitation (LASAN) with regulatory consulting services since the late 1990s. LWA has supported the City develop effective policy and technical solutions for their wastewater and stormwater programs, including the following wastewater program support:

  • Negotiations on NPDES permits for all three of the City’s inland water reclamation plants and one ocean outfall plant, including: Review and comment on all Tentative NPDES permits since 1998, conduct Reasonable Potential Analysis (RPA) and calculation of effluent limitations, review of monitoring requirements.
  • Development of ammonia and copper water-effect ratio studies that were adopted by the State and accepted by USEPA.
  • Completion of dilution modeling for the Terminal Island Water Reclamation Plant (TIWRP) resulting in the application of dilution credits.
  • Completion of a Title 22 Engineering Report for the expansion of the TIWRP Advanced Water Treatment Facility.
  • Conducting review of and comment on Total Maximum Daily Loads (TMDLs).
Clear water lake shoreline

Watershed Management and TMDLs

LWA’s watershed management and TMDL (Total Maximum Daily Load) assistance includes development of TMDLs for nutrients, toxicity, organophosphate and organochlorine pesticides, metals, salts and bacteria as part of a coordinated stakeholder process. As part of the TMDL development, LWA conducts a review of applicable water quality standards (including the development of site-specific criteria), beneficial uses, and data used to develop the 303(d) listings. LWA develops technical work to support the TMDL development, provides support on policy and regulatory issues, and coordinates stakeholder and regulatory agency participation and communication.
Additionally, LWA provides review and comment for the 303(d) listing process and TMDLs, provides support to regulators and regulated agencies during Regional Water Board TMDL development, and assists with TMDL implementation requirements, such as watershed monitoring and BMP implementation.

Central Valley Sustainable Alternatives for Long Term Salinity (CV-SALTS)

LWA has been actively involved in and completed projects for CV-SALTS for over five years. Our Team for these projects includes Carollo Engineers, Kennedy/Jenks Consultants, Systech Water Resources, PlanTierra, Luhdorff and Scalmanini Consulting Engineers, Giorgos Kourakos, Formation Environmental, and Ascent Environmental.

Our involvement includes participation in the Executive Committee, Technical Advisory Committee (TAC), and Knowledge Gained Subcommittee as well as work on the Salt and Nitrate Sources Pilot Implementation Study (February 2010), the Knowledge Gained Subcommittee memo, A Framework for Salt/Nitrate Source Identification Studies (December 2011), the Initial Conceptual Model (ICM) (December 2013), the Geographic Information Services (January 2014), the development of water quality objectives for salinity on the Lower San Joaquin River (LSJR) (ongoing), the development of a Preliminary Draft Salt and Nitrate Management Plan (SNMP) (ongoing), and the development of supporting information for the proposed de-designation of the MUN and AGR beneficial uses in the Tulare Lake Bed (ongoing).

The development of a SNMP for the entirety of the jurisdiction of the Central Valley Regional Water Quality Control Board is ongoing and has occurred in the following phases:

  • Phase I (2012-2013) included development of an Initial Concept Model (ICM) which is a concept level analysis estimating salt and nitrate load balances for the Central Valley floor in 22 areas that are referred to as Initial Analysis Zones (IAZs).
  • Phase II (2013-2015) includes development of the preliminary draft SNMP which utilizes data collected and/or organized in Phase I to identify the approach and establish the basis for the short and long term management of salt and nitrate in the entirety of the Central Valley region. The SNMP will form the basis for corresponding amendments to the Water Quality Control Plans for the Sacramento/San Joaquin Basin and Tulare Lake Basin.
  • Phase III (2015-2017) will focus on work to support the additional required elements of the SNMP and Basin Plan amendments, such as refinement of the preliminary draft SNMP, development of a monitoring/surveillance plan, as well as development of documents that are necessary under the California Water Code and Clean Water Act for the regulatory approval process for the adoption of the SNMP and corresponding Basin Plan amendments (anti-degradation analysis, the economic analysis of implementation alternatives, CEQA analysis).

It is anticipated that upon completion of Phase III and the adoption of the comprehensive SNMP, local SNMPs may be developed and implemented by local/regional entities, as needed. The local SNMPs will be informed by prototype and archetype methods, as well as the implementation measures recommended in the final, adopted SNMP.

Calleguas Municipal Water District

LWA provides technical water quality support to the Calleguas Creek Watershed Management Plan (CCWMP), assisting in watershed planning, monitoring, and management activities. Since 1998, our work has included:

  • Stakeholder facilitation
  • TMDL development and implementation
  • Monitoring current loads, pollutant sources, and evaluate progress in attaining TMDLs
  • Preparation of regulatory agency reports
  • Review of water quality standards, regulations, plus development and implementation of studies to support Basin Plan changes
  • Development of analysis and management tools for water quality models and databases
  • Support of MS4 permit negotiations

In 1998 LWA developed and implemented the Calleguas Creek Characterization Study (CCCS) to assess surface water, discharge, and groundwater conditions and to identify constituents of concern and pollutant sources in the watershed. Additional Work Plans were developed to complete TMDLs for salts, metals, bacteria, toxicity, pesticides and PCBs.

LWA facilitated meetings with stakeholders and were responsible for working with the broad stakeholder group, the Regional Board, and USEPA to develop scientifically defensible and reasonable TMDLs. TMDL reports developed by LWA for the CCWMP have to-date formed the basis for five TMDLs adopted by the State and USEPA (Nutrients, Toxicity TMDL, Organochlorine Pesticides and PCBs, Metals, and TDS, Sulfate, and Boron TMDL, which included a specific implementation plan for Chloride). Additionally, as part of the TMDL development process LWA worked with stakeholders to develop and implement several special studies including a Water-Effect Ratio (WER) for copper, a watershed-scale microbial source tracking study, a nutrient loading and algae impairment study, and a dry season urban runoff characterization study. The results of the WER study were adopted into the Los Angeles Region Basin Plan in 2006.

As a component of the Bacteria TMDL and in conjunction with researchers from the University of California at Davis, the microbial source tracking study was conducted. The goal of this study was to provide information regarding which land uses (urban, agricultural, etc.) and source types (human vs. non-human) are responsible for beneficial use impairments.

Following the completion of the TMDL development efforts, LWA initiated the development of the Calleguas Creek Watershed TMDL Compliance Monitoring Program (CCWTMP) covering all TMDL monitoring requirements for all responsible parties participating in the CCWMP. The effort to complete this coordinated monitoring program included site selection, completion of a Regional Water Quality Control Board approved Quality Assurance Project Plan (QAPP) covering all TMDL monitoring requirements, coordinating with existing waste water treatment plant monitoring efforts, management of the collection of water, tissue, and sediment sampling efforts, compilation and management of new and historic data, and completing all required annual report.

Vineyard at edge of water

Agricultural Water Quality Management

California Water Code authorizes Regional Water Boards to conditionally waive waste discharge requirements (WDRs) for surface water discharges if it is in the public interest. A number of Regional Water Boards have adopted waivers for discharges from irrigated agriculture on the condition that coordinated programs are implemented to assess and control, if necessary, impairment from pesticides, sediment, salts, nutrients, pathogens and metals.Larry Walker Associates has been instrumental in assisting agricultural communities in three California regions to comply with the adopted Conditional Ag Waivers, including the Central Valley, Central Coast and Los Angeles Regions.
Assistance provided includes commenting on draft waivers, assisting agricultural communities to form coordinated discharger groups for compliance, developing and implementing monitoring programs, submitting required monitoring reports for the agriculture groups, and providing consulting services regarding Best Management Practices (BMPs) to prevent discharges from agricultural lands from causing water quality impairments. Additional services include development of processes to collect funds from agriculture group members, and creating and maintaining databases to efficiently manage membership and water quality monitoring data.

Ventura County Agricultural Irrigated Lands Group

LWA provides regulatory assistance to the Ventura County agricultural community for compliance with the Conditional Waiver of Waste Discharge Requirements for Discharges from Irrigated Lands (Conditional Ag Waiver). Working with the local Farm Bureau since 2004, LWA provides assistance in negotiations and support including:

Formation of the discharger group (VCAILG) as well as developing and maintaining a membership database for over 1,300 enrollees, approximately 3,000 parcels, and over 78,000 irrigated acres.

Compiled membership statistics and information on cultural practices to complete both of VCAILG’s Notices of Intent (NOI), complying with the 2005 and 2010 Conditional Ag Waivers.

Developed the 2005 and 2010 QAPP and MRP Plans, assisting with selection of 24 and27 monitoring sites, respectively, within the three major Ventura County watersheds and conducted site assessments to verify relevance to the monitoring program and safe access for compliance with both the Conditional Ag Waivers and effective Total Maximum Daily Loads (TMDLs).

Led the 2005 and 2010 Conditional Ag Waiver monitoring efforts, with two dry and two wet weather monitoring events annually for toxicity (including a 3-species screen for the first event; toxicity sampling occurs twice annually), pesticides, nutrients, salts, copper, general water chemistry parameters (i.e., flow, DO, pH, TSS), and additional TMDL specific constituents.

Developed and maintains the database for data collected at each monitoring event. A separate database contains current enrollment, parcel, ownership, and grower records, as well as education credits. A website was developed for members to track and report their implementation of management practices as well as crop specific information related to irrigation type(s), ground, and overhead cover.

LWA is responsible for preparing all necessary documentation and reports for submittal to the Regional Board, including Annual Monitoring Reports summarizing membership and monitoring data, and for development of Water Quality Management Plans (WQMPs) triggered by exceedances of water quality benchmarks or as required by certain TMDLs. Implementation of the WQMP began in 2008; this process includes surveying growers to identify current Best Management Practice implementation and provide outreach and guidance in areas that could be improved in order for agriculture to meet Conditional Waiver water quality benchmarks and TMDL load allocations. Additionally, LWA is assisting the agricultural community with effective TMDL compliance and the review and comment process during new TMDL development.

Sacramento Valley Water Quality Coalition Irrigated Lands Regulatory Program

The Sacramento Valley Water Quality Coalition (SVWQC) implemented a Monitoring and Reporting Program (MRP) for the Sacramento River watershed in 2005. Larry Walker Associates is the lead consultant helping SVWQC comply with all aspects of the Central Valley Regional Water Quality Control Board’s previous Conditional Waivers and the current Waste Discharge Requirements (WDR) for the Irrigated Lands Regulatory Program (ILRP). The purpose of the MRP is to assess sources and impacts of waste in discharges from irrigated lands and track progress in reducing adverse impacts on the quality of the waters in the state.

LWA’s consultation, guidance and support includes:

  • Assistance in negotiating the scope of the WDR and MRP with the Regional Board
  • Preparation and maintenance of the QAPP, development of the project implementation plan, and management of all monitoring
  • Development and maintenance of a custom SWAMP-compatible database, with validation of data and evaluation of all quality assurance results, and coordination of data submittals from several coordinating sub-watershed agencies, and submittals of monitoring data to the Water Board
  • Coordinate communications and reports to the Regional Board, including evaluations of compliance with numerical and narrative Basin Plan objectives for water chemistry and toxicity
  • Develop and implement management plans required by the ILRP to address exceedances of water quality objectives and ILRP Trigger Limits, including source evaluations to identify, assess, and prioritize potential causes and sources of toxicity, pesticides, pathogen indicators, and nutrient compounds
  • Assistance with interpretation of Regional Board policy, and with outreach and education programs for sub-watersheds, landowners, and growers
  • Participation in the Technical Issues Committee that provides technical guidance to the Central Valley Regional Water Quality Control Board on the design and modification of the Irrigated Lands Program MRP
  • Participation in the Delta Regional Monitoring Program (RMP) as a representative on its Technical Advisory Committee
  • Participation as a representative in the ILRP Pesticide Evaluation Advisory Workgroup