Delta Water Quality - Effects of Ambient Ammonia Concentrations

Recent studies and analyses indicate ammonia may be impacting Delta species. The Regional Water Board, in cooperation with multiple agencies and interested stakeholders, is evaluating the role of ammonia on the Sacramento-San Joaquin Delta and Suisun Bay ecosystem.

Summary of Water Board Studies

Ammonia Summit

Date: August 18-19, 2009
Time: 9:00 a.m. to 4:30 p.m.
Location: Central Valley Regional Water Board
11020 Sun Center Drive, #200
Rancho Cordova, California

The Ammonia Summit was part of an integrated series of public workshops coordinated by the Interagency Ecological Program (IEP) in 2009. More information about the other workshops in this series can be found at

This workshop was intended to provide a forum to present findings of current research and gather scientific information relevant to the study of the role of ammonia in the Bay-Delta ecosystem.  Members of the Regional Water Board were in attendance; however, no action was taken by the Board during this workshop.

The workshop included scientific presentations and discussions among presenters and the audience covering various topic areas, including: sources, concentrations, fate and transport; food web dynamics; and toxicology.  This workshop was open to the public.

  • Draft Agenda - (updated 25 August 2009)
  • Abstracts - (updated 25 August 2009)
  • Presentations:
    • F.Wilkerson - Is There Suppression of Algal Production in Suisun Bay?
    • A. Parker -Effect of Wastewater Treatment Plant Effluent on Algal Production in the Sacramento River Part 1: Grow-out and Wastewater Effluent Addition Experiments
    • A. Parker -Effect of Wastewater Treatment Plant Effluent on Algal Production in the Sacramento River Part 2: Transect Results
    • D. Dugdale - Transport of Nutrients From Sacramento River to Suisun and Grizzly Bays: Effects on River and Bay Chlorophyll Concentrations
    • C. Mioni - Does Ammonia Control Harmful Algae Abundance and Toxicity in the San Francisco Estuary, CA?
    • P. Lehman - Microcystis and Ammonium
    • S. Teh - Acute Toxicity of Ammonia, Copper, and Pesticides to Eurytemora affinis and Pseudodiaptomus forbesi
    • I. Werner - Effects of Ammonia/um and Wastewater Effluent Associated Contaminants on Delta Smelt
    • D. Engle - Total Ammonia and Unionized Ammonia Concentrations in the Delta; an Examination of Ambient Concentrations and Toxicity Thresholds
    • M. Johnson - Species Sensitivity Distributions and Exposure Concentrations; Placing Recent Results into Context
    • D. Fullerton - Ammonia Concentrations and the Food Chain in Suisun Bay and the Delta
    • C. Foe - Preliminary Ammonia Results from an Ongoing Monitoring Program
    • C. Kendall - Tracing Sources and Biogeochemical Cycling of NH4 and NO3 in the Sacramento River, Delta, and Northern Bay Using Stable Isotope Techniques
    • M. Guerin - Fate and Transport Modeling of Ammonia in the Delta using DSM2
    • E. Van Nieuwenhyse - Nutrient Limitation of Average Summer Chlorophyll Concentration in the Freshwater Delta
    • P. Gilbert - Ammonium – Global Trends, Issues on the East Coast, and Implications for Plankton Dynamics
    • A. Vargas - Development of a Ammonia/Ammonium Research Framework for the Delta and Suisun Bay
    • C. Irvine - Data (and Science) Gap Analysis (DaSGA) for Determining the Potential Influence of Ammonia/um on the POD

CALFED Science Program Workshop: The Development of a Research Framework to Assess the Role of Ammonia/Ammonium on the Sacramento-San Joaquin Delta and Suisun Bay Ecosystem.

Date: March 10 and 11, 2009
Time: 9:00 am - 5:30 pm
Location: CALFED Offices
650 Capitol Mall, 5th Floor
Delta Room

The purpose of the workshop was to provide a venue for open discussion among interested parties to identify data and science gaps and develop a scientific research framework to determine the role of ammonium and ammonia within the Sacramento-San Joaquin Delta (Delta) and Suisun Bay ecosystem. A panel of national experts (Panel) in riverine and estuarine nutrient dynamics, food web processes, and ecotoxicology assessed the best available science in a workshop setting. The Panel developed a Research Framework with input from local experts (invited scientists conducting research in the Delta and Suisun Bay relative to the topic of interest in the workshop), stakeholders (invited interest groups and entities who have been engaged in the issue of ammonium-ammonia in the Delta and Suisun Bay), and the interested public. This research framework, combined with input from local experts and stakeholders during workshop discussions, will be used to develop a listing of specific research needs and priorities in a Data and Science Gap Analysis. Details can be found at: