Practical methods to find polluted areas in urban stormwater catchments to support management actions

San Francisco Estuary Institute (SFEI) | January 14th, 2022

Predicted Water-Level and Water-Quality Effects of Artificial Recharge in the Upper Coachella Valley, California, Using a Finite-Element Digital Model

U.S. Geological Survey (USGS) | April 15th, 1978

This study was begun in mid-1973 by the U.S. Geological Survey in cooperation with the Desert Water Agency (DWA) and the Coachella Valley County Water District (CVCWD). T

This study was begun in mid-1973 by the U.S. Geological Survey in cooperation with the Desert Water Agency (DWA) and the Coachella Valley County Water District (CVCWD). The purpose of the study was to (1) analyze the present water quality conditions of the ground-water basin, (2) determine the water-level changes that will result from recharging the aquifer, and (3) determine the water-quality changes that will result from recharging the aquifer. The study included: (1) Collecting, evaluating, tabulating, and computer processing all available ground-water-quality data for the study area; (2) describing the areal distribution of water quality throughout the ground-water basin; (3) updating the pumpage and other hydrologic data compiled for the analog model of the study area (Tyley, 1974); (4) developing a digital hydraulic (flow) model utilizing the finite-element method; and (5) developing a digital solute-transport (water quality) model utilizing the finite-element method. This report presents the results of the 3-year study and the predictions of the possible effects of ground-water recharge on the water resources of the upper Coachella Valley.

Predicting Redox Conditions in Groundwater at a National Scale Using Random Forest Classification

American Chemical Society (ACS) | March 7th, 2024

Predicting Sediment Bulk Density for San Francisco Estuary

University of California, Davis (UC Davis) | December 19th, 2025

Sediment bulk density (ρ-dry) and particle size are two important parameters for predicting sediment bed erosion. ρ-dry, however, is difficult to measure accurately. Th

Sediment bulk density (ρ-dry) and particle size are two important parameters for predicting sediment bed erosion. ρ-dry, however, is difficult to measure accurately. The units of ρdry have not been consistently reported in the literature, leading to confusion, particularly in the calculation of sediment budgets that typically require integrating mass-based and volumetric components. Relationships between ρdry and sediment composition have been developed for multiple regions and differ between systems. Developing a system-specific predictive model for ρdry can help fill data gaps and improve sediment budgets, model accuracy, and estimates of quantities of sediment needed for restoration. In this study, we investigate whether ρdry in San Francisco Estuary can be predicted from organic carbon content or percent of fines, which are more easily or frequently measured than ρdry. We compiled sediment properties from samples collected over the past decade throughout the intertidal and subtidal regions of San Francisco Bay and the Sacramento–San Joaquin Delta to examine this relationship. Sample composition ranged from 2.18 to 99.97% fines (particles < 0.0625 mm), ρ-dry ranged from 0.22 to 1.60 g cm-3, and organic carbon ranged from 0.06 to 7.98%. Regression analysis indicates that the percent of fines explains 93% of the variation of ρ-dry (p-value < 0.05, N = 81). The coefficient of determination decreased by ~1% when organic carbon was incorporated in the regression analysis. Comparison of this predictive ρ-dry model to four published models based on samples from other regions supports previous findings that the relationship between ρdry and grain size may vary by system. We also examined additional factors that may affect sediment erodibility, such as hydrographic and oceanographic conditions. Classification of sample sites as intertidal vs. subtidal or wavy vs. non-wavy each significantly explained the residuals from the ρdry model, and both intertidal and wavy conditions were associated with higher ρ-dry values.

Primary Production in the Delta: Then and Now

University of California, Davis (UC Davis) | October 3rd, 2016

To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function

To evaluate the role of restoration in the recovery of the Delta ecosystem, we need to have clear targets and performance measures that directly assess ecosystem function. Primary production is a crucial ecosystem process, which directly limits the quality and quantity of food available for secondary consumers such as invertebrates and fish. The Delta has a low rate of primary production, but it is unclear whether this was always the case. Recent analyses from the Historical Ecology Team and Delta Landscapes Project provide quantitative comparisons of the areal extent of 14 habitat types in the modern Delta versus the historical Delta (pre-1850). Here we describe an approach for using these metrics of land use change to: (1) produce the first quantitative estimates of how Delta primary production and the relative contributions from five different producer groups have been altered by large-scale drainage and conversion to agriculture; (2) convert these production estimates into a common currency so the contributions of each producer group reflect their food quality and efficiency of transfer to consumers; and (3) use simple models to discover how tidal exchange between marshes and open water influences primary production and its consumption. Application of this approach could inform Delta management in two ways. First, it would provide a quantitative estimate of how large-scale conversion to agriculture has altered the Delta's capacity to produce food for native biota. Second, it would provide restoration practitioners with a new approach—based on ecosystem function—to evaluate the success of restoration projects and gauge the trajectory of ecological recovery in the Delta region.

Primary Production in the Sacramento-San Joaquin Delta: A Science Strategy to Quantify Change and Identify Future Potential

San Francisco Estuary Institute (SFEI) | May 20th, 2019

Today’s Sacramento-San Joaquin Delta is an unusually low-productivity estuary. The constraints on primary production and the relative importance of different production

Today’s Sacramento-San Joaquin Delta is an unusually low-productivity estuary. The constraints on primary production and the relative importance of different production sources to the food web are major ecological uncertainties in the Delta system. Understanding how the extensive historical changes in the Delta landscape have altered primary production has the potential to inform restoration planning and management across the region.  The Delta Landscapes Project (SFEI-ASC 2014) has recently produced information that allows us, for the first time, to answer questions about historical primary production and carrying capacity from quantified changes in the areal extent and spatial configuration of habitat types in the Delta since the mid-19th century. Our focus is on estimating primary production because the potential capacity of ecosystems to support fish, bird and other wildlife populations is set by primary production – the supply of food required to produce animal biomass. 

Principles for Agreement on Bay-Delta Standards Between the State of California and the Federal Government

California State Water Resources Control Board (SWRCB) | December 15th, 1994

In order to provide ecosystem protection for the Bay-Delta Estuary, representatives of the State and Federal governments and urban, agricultural and environmental interes

In order to provide ecosystem protection for the Bay-Delta Estuary, representatives of the State and Federal governments and urban, agricultural and environmental interests agree to the implementation of a Bay-Delta protection plan through the California State Water Resources Control Board (SWRCB) consistent with the following principles.These Principles describe changes to the California Urban Water Agency/-Agricultural Water Users (CUWAIAG) proposal as the base case for Bay-Delta protections, which are intended to be in force for three years, at which time they may be revised.

Prioritizing Candidate Green Infrastructure Sites within the City of Ukiah: A Demonstration of the Site Locator Tool of GreenPlan-IT. Report prepared for the City of Ukiah Department of Public Works under Supplemental Environmental Project # R1-018-0024

San Francisco Estuary Institute (SFEI) | April 1st, 2019

Green infrastructure (GI), also known as Low Impact Development (LID), has emerged as an integral aspect of multi-benefit, watershed approaches to address concerns about

Green infrastructure (GI), also known as Low Impact Development (LID), has emerged as an integral aspect of multi-benefit, watershed approaches to address concerns about stormwater quality and quantity in an urban environment. When carefully applied, GI installations, such as rain gardens, tree-well planters, and permeable pavement, can be cost-effective, resilient ways to manage storm water at its source with measurable, cumulative environmental and community benefits. 

Priority Margin Unit Stormwater Monitoring to Support Load Estimates of PCBs into San Leandro Bay and the Emeryville Crescent

San Francisco Estuary Institute (SFEI) | July 15th, 2022

The Priority Margin Unit Studies: The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the  PCB Synthesis Report (D

The Priority Margin Unit Studies: The 2014 update of the RMP PCB Strategy called for a multi-year effort to implement the recommendations of the  PCB Synthesis Report (Davis et al., 2014) including: 1. identifying margin units that are high priorities for management and monitoring, 2. developing conceptual models and mass budgets for margin units downstream of watersheds where management actions will occur, and 3. monitoring in these units as a performance measure. The goal of the effort was to inform the review and possible revision of the PCB TMDL and the reissuance of the Municipal Regional Permit for Stormwater (MRP).

Probabilistic Assessment of the Biotic Condition of Perennial Streams and Rivers in California

Central Valley Regional Water Quality Control Board (CVRWQCB) | August 22nd, 2006

States are required under the Clean Water Act §305(b) to report annually to Congress on the condition of their waterbodies, but satisfaction of this requirement has been

States are required under the Clean Water Act §305(b) to report annually to Congress on the condition of their waterbodies, but satisfaction of this requirement has been confounded by the lack of resources (both technical and financial) to adequately assess these waterbodies. Partly because of this limitation, most regions of the nation have been unable to answer the most basic questions about their water quality, even 35 years after the passage of the act. To address these constraints, the U.S. EPA established its Environmental Monitoring and Assessment Program (EMAP), a long term research program designed to develop the tools and techniques needed for cost-effectively answering the fundamental status and trends questions in the Clean Water Act. The EMAP studies are based on a probabilistic survey design in which each sampling location represents a known length of stream with known statistical confidence. This design permits the inference of stream conditions for large geographic regions with a relatively small investment in sampling. After completing an assessment of the condition of wadeable streams in the Middle-Atlantic states, the EPA initiated a similar assessment of streams in the western states (WEMAP), which included a high density of sites in California. Now that the first round of WEMAP studies has been completed, California has the ability to include the first statistically defensible condition assessments in its 305b reports. Because they provide a direct measure of the biotic integrity, bioassessment data are a key component of EMAP water quality monitoring. Bioassessment, the science of describing the ecological condition of waterbodies from the assemblages of organisms they contain, is well established as a valuable tool for water resource management (Karr 1981, Yoder and Rankin 1995, Barbour et al. 1996, Wright et al. 2000, Bailey et al. 2004). Because assemblages of aquatic organisms (e.g., fish, benthic macroinvertebrates (BMIs) and algae) are comprised of taxa that are differentially responsive to different environmental stressors, bioassessments provide a direct means of measuring compliance with the goal of biotic integrity stipulated under the Clean Water Act. Although comprehensive condition assessments will ultimately include assessments of the physical and chemical conditions of waterbodies, condition assessments based on bioassessment data can stand alone as effective measures of the ecological condition of the state’s waterbodies. There are many different approaches to translating a list of organisms present at a site into an assessment of its ecological condition (Wright et al. 1984, Kerans and Karr 1994, Hawkins et al. 2000, Van Sickle et al. 2005, Ode et al. 2005). We have demonstrated elsewhere (Rehn and Ode 2004, Rehn and Ode 2005) the use of BMI data to produce regional 305(b)-type stream condition assessments using multimetric techniques to calculate site condition scores. These regional assessments were possible because we had previously developed benthic indices of biotic integrity (B-IBIs) for northern and southern coastal California; statewide assessments require a tool for scoring sites that can be applied statewide. We present here a statewide condition assessment using predictive models based on the River Invertebrate Prediction and Classification System (RIVPACS, Wright 1984). Like multimetric approaches (Kerans and Karr 1994, Ode et al. 2005, Rehn and Ode 2005), predictive modeling techniques establish thresholds of ecological impairment based on a characterization of the biotic assemblages expected to occur under minimal human disturbance (Wright et al. 1984, 1989, 2000). However, predictive models compare assemblages at test sites to an expected taxonomic composition rather than expected metric values. Taxon-based models have seen widespread use since the first BMI models were created in Great Britain in the late 1970s (Norris and Georges 1993, Hawkins et al. 2000, Van Sickle et al. 2005) and have been promoted in the US (Hawkins et al. 2000, Hawkins and Carlisle 2001) as an alternative to the multimetric approach initially endorsed by the EPA (Barbour et al. 1999). For this analysis, we employed newly developed California RIVPACS models (C. Hawkins unpublished) that can be used to score sites throughout the state.