TMDL for Fecal Coliform for the Lower Salinas River Watershed, Monterey County, California

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This page is a a summary of the Regional Water Quality Control Board Central Coast Region report on Total Maximum Daily Load for Fecal Coliform for the Lower Salinas River Watershed, Monterey County, California (RWQCB, 2009)[1] by the Spring '10 ENVS 560/L Watershed Systems class at CSUMB.

Project Definition

The California Regional Water Quality Control Board for the Central Coast Region (CCRWQCB), in collaboration with the Environmental Protection Agency (EPA), established the Total Maximum Daily Load (TMDL) for Fecal Coliform for the Lower Salinas River Watershed in Monterey County, California. The final TMDL report was available March 18, 2010.

The TMDL report addresses the impairment of the Lower Salinas River and several of its tributaries as a result of increased fecal coliform concentrations. The fecal coliform group of bacteria (otherwise known as 'fecal indicator bacteria' (FIB)) are used to help identify water body contamination from pathogens. If fecal coliform concentrations exceed certain criteria, the water body may be listed as impaired pursuant to Section 303(d) of the Clean Water Act. The project area includes the following impaired water bodies:

  • Lower Salinas River (from Gonzales downstream to the Salinas River Lagoon)
  • Old Salinas River
  • Tembladero Slough
  • Salinas Reclamation Canal
  • Gabilan Creek
  • Alisal Creek
  • Natividad Creek
  • Santa Rita Creek
  • Quail Creek
  • Chualar Creek
  • Towne Creek

Each water body covered by the TMDL is categorized based upon its specific purposes (beneficial uses). When a water body fails to meet the minimum quality standards required for its beneficial uses, a TMDL must be established. The water bodies of the Lower Salinas watershed are used for a variety of purposes including, but not limited to: groundwater recharge, wildlife habitat, industrial and agricultural supply, commercial and recreational fishing, and other recreational activities.

Watershed Description

The project area is bounded by the Gabilan Range to the east, the Sierra de Salinas range to the west, and the Monterey Bay to the northwest.
TMDL Project Area
The TMDL study is defined by the lower 400 square miles of the Lower Salinas Valley and includes two major watersheds, the The Gabilan / Reclamation Ditch Watershed and The Lower Salinas Watershed.

Surface water sources include precipitation, releases from reservoirs, groundwater, and return flows from agricultural irrigation. Mean annual precipitation in the project area ranges from approximately 13 to 16 inches per year with the majority of precipitation occurring between November and April.

Land use in the project area includes intensive agriculture as well as the urban centers of Salinas, Castroville and Prunedale.

The project area is characterized by both ephemeral and perennial stream reaches, as the Lower Salinas River is dry in the summer months, but the lower Reclamation Ditch flows year-round.

Problem Statement

The Lower Salinas River and eleven of its tributary water bodies are listed as impaired under section 303(d) of the Clean Water Act due to elevated levels of fecal coliform. Observed levels of fecal coliform for some or all these water bodies do not meet the water quality objectives for the following beneficial uses (BUs) designated in the basin plan:

  • Water contact recreation.
  • Non-contact water recreation.
  • Shellfish harvesting for human consumption. (This BU is under review, and may be eliminated)


Data Analysis

The salinas watershed was found to be impaired as a result of elevated concentrations of Fecal Indicator Bacteria (FIB). FIB's were monitored as a method for indicating human pathogens, which by themselves are difficult and expensive to measure individually. There is, however, a scientific uncertainty about the effectiveness of FIB as an gauge for pathogen risk, but despite this there are few alternatives that produce satisfactory results.

Escherichia coli (E. coli) composes a large percentage of coliforms in sewage. The potential presence of fecal coliform and E. coli, can be determined through water sample analysis. Most E. coli strains are harmless and reside naturally in the intestines of humans and animals, but the E. coli O157:H7S strain can be a deadly human pathogen. Therefore, the identification of E. coli O157:H7 strain can indicate the magnitude of a pathogen problem while also demonstrating the very probably presence of other fecal pathogens.

Several analytical methods were used in quantifying coliforms in this TMDL study. These included the Multiple Fermentation method (MFT) and the Colilert method. These two tests were then combined with the identification and presence of E. coli O157:H7 which provided a strong indication of the presence and magnitude of pathogens, and as a result the water quality.

This study required a qualitative and quantitative approach and as a result various types of data were used. Spatial data was utilized via Geographic Information Systems (GIS) software and layers included streams, watershed boundaries, roads and land use. Hillshade layers were also created from digital elevation models (DEM) of the project area. FIB concentrations and presence were collected from various sites within the study area during the dry and wet seasons. It was found that there was a general trend of higher FIB during the rainy season, relative to the drier summer months. Flow data was used from USGS flow data to estimate existing loading, assimilative capacity and to derive daily load expressions for informational purposes. However, flow data was not collected as a part of the project as it is not necessary for TMDL allocation calculations. Rain event data was also collected form thirteen sites after two separate rain events, neither of which were first flush rain events. It was found that Median E.coli density was significantly higher during rain events (2,685 MPN/100mL) than non rain events (224 MPN/100mL). Other investigations into E. coli O157:H7 found multiple positive identification. This was mostly at the confluence of Gabilan Creek and Towne Creek in the northern part of the study area which coincided with mostly pasture and shrubland use. This was to be expected as these areas possess large amounts of ranch land with animal activity.

As a result of the study, it was found that the listed waterbodies were impaired on the basis that water quality exceeded the recommended level for FIB:

  • Lower Salinas River
  • Old Salinas River
  • Tembladero Slough
  • Reclamation Canal
  • Alisal Creek
  • Gabilan Creek
  • Natividad Creek
  • Salinas River Lagoon
  • Santa Rita Creek
  • Quail Creek
  • Chualer Creek
  • Town Creek

Other Assessed waterbodies for which data dod not indicate impairment, or for which data was insufficient were:

  • Blanco Drain-not impaired
  • El Toro Creek-insufficient data
  • Alsal Slough-insufficient data

Numeric Target

Water quality objectives for FIB are established in the basin plan based on the designated beneficial uses of a given water body. In all or some of the Lower Salinas area, the numeric standards for Water Contact Recreation, Non-Contact Recreation, and Shellfish Harvesting are not being met. As shellfish harvesting is likely to be eliminated as a protected beneficial use, the numeric target for this TMDL has been set equivalent to the water quality standard for Water Contact Recreation, which is the next most protective. The goal is for all water bodies in the TMDL area to meet this standard:

  • The total coliform concentration for a minimum of five samples in any 30 day period should not exceed a log mean of 200 per 100 ml, or 400 per 100 ml for 10% of total samples in any 30 day period.

Linkage Analysis

The Linkage Analysis is intended to link the numeric target concentration (amount per volume) to a daily load (amount per day) for the watershed. In the case of fecal coliform, the RWQCB expresses the intent to implement the TMDL based on the target concentration rather than load allocation, and therefore, no explicit linkage analysis is given. However, under 'TMDL Development' methods are described for linking target concentrations to loading capacity.

TMDL Development

The official TMDL objective is expressed as a numeric target concentration that applies to all included water bodies. However, additional analysis is given linking the target concentration to maximum allowable loads for each individual water body, which meets the more traditional interpretation of the TMDL approach.

The TMDLs for fecal coliform are based on a three tiered flow regime, wherein each water body has different allowable loads established for high (top 5%), moderate (middle 25%), and low (bottom 60%) flows. Allowable loads were calculated by multiplying the average flow within each flow regime (low, moderate, or high) by the target concentration [volume/time * mass/volume = mass/time]. These target loads were then compared to existing loads derived from field data.

For example, at Gabilan Creek, during an average high flow event of 26 cfs, the Total Maximum Daily Load of FIB that can be absorbed without exceeding the target concentration is 2.8x10^11. This represents an 89% reduction from the current estimated load of 2.62x10^12.

The method described above is dependent on streamflow data. For streams where this data was unavailable, flow was estimated by taking flow for a comparable stream and adjusting it based on the Drainage Area Ratio (DAR) of the two streams. Flow at coastal confluences also had to be estimated, as stage data from these areas is complicated by tidal fluctuation.

Margin of Safety

TMDLs are required to include a margin of safety that accounts for uncertainty in the linkage between loading capacity of the watershed and pollutant concentration in the receiving water. In the case of fecal coliform, the goal is for all controllable water sources to meet the target concentration. As this is not a load-based approach, no margin of safety is given.

Critical Conditions and seasonal variation

This TMDL does not identify any "critical" environmental factors, in which a slight change could lead to exceedence of water quality objectives. However, it is noted that pollutant concentration is dependant on flow volume, which is often irregular in Monterey County. Also, localized areas of stagnant water with fine sediments foster bacterial growth and as such may increase concentrations of Fecal Indicator Bacteria.

TMDL Allocations

Wasteload and load allocations are equal to the TMDLs expressed as receiving water concentrations. For non-human fecal indicator bacteria, allocations are the numeric target for fecal coliform and equal to the concentration-based TMDL. The allocation assigned for human FIB is zero due to the increased pathogenic risk related to human waste. Wasteload and load allocations to responsible parties associated with the waterbodies along with sources of indicator bacteria identified are shown in Table 10-1 of the TMDL report.

Public Participation

There are many stakeholders in the Lower Salinas Watershed who would be affected by the implementation of the fecal coliform TMDL. These would include:

  • Agricultural
  • Industry
  • Sewer discharge facilities
  • Wildlife
  • Fisheries
  • Sporting recreational activities
  • Municipal and domestic water supply
  • Homeless Persons

CCRWQCB made stakeholder outreach efforts throughout the development of the TMDL. Data collection and analysis were organized in collaboration with county, state and federal agencies. Public presentations were conducted to inform and elicit stakeholder opinion from a variety of public and private institutions. All the results were made public.

Stakeholders had the opportunity to participate in public meetings where they asked questions and voiced their concerns. One of the concerns described was that some stakeholders claimed specific water bodies in the project area cannot achieve the minimum contaminant levels required for coliform bacteria. The stakeholders added that these water bodies are on private land that have other uses besides recreational. Water flow on these lands is not always natural, especially during summer months when irrigation and groundwater pumping is used widely. Increased concentrations of the fecal indicator bacteria in these water bodies may result from evaporation, and so the minimum required numeric water quality objectives may be exceeded. Furthermore, the steep embankments and muddy substrate surrounding these water bodies makes them inappropriate for recreational use. The CCRWQCB is responsible for addressing these concerns and comments, and for providing official responses before the TMDL listing is approved.

Implementation and Monitoring

The goal of implementation and monitoring is to reduce pathogen loads and achieve the stated TMDLs for the Salinas River Watershed. The implementation of TMDL is complex because of the various sources of pathogenic pollutants. A number of sources of fecal coliform in the Lower Salinas Watershed were identified in the TMDL report. These included point sources (a single identifiable localized source of pollution; you know exactly where the pollution is coming from and can quantify it). Examples of point sources of pollution are storm drain discharges to storm sewer systems, spills and leaks from sanitary sewer collection and treatment systems, and concentrated animal feeding operations and dairies (none identified within project area). Nonpoint sources are pollution derived from many different diffuse sources (i.e. regulation of one point or source will not rectify the problem). Some examples of nonpoint sources include domestic animal discharges in areas that do not drain to a storm water sewer system, onsite waste disposal systems, illegal dumping, homeless encampments, sediment sources, runoff from irrigated agriculture, and non-controllable natural sources (wind-borne debris).

The report lays out an implementation and monitoring road map to identify key pollutants, record progress, and take action to obtain results. In accordance with NPDES permitting rules, MS4 Stormwater Permit requirements and Nonpoint Source Implementation Program guidelines as requested by the CCWB, pursuant to California Water Code Section 13267 or 13383, the responsible parties submit reports to the CCWB outlining implementation and monitoring results.

Implementation

  • Implementation Actions: Mandatory municipal storm water permits require all those who discharge to municipal storm sewage systems to implement a Storm Water Management Plan that includes an effectiveness assessment strategy. Compliance with the Domestic Animal Waste Discharge Prohibition is required for all owners and/or operators of property that have livestock, farm animals and pets. Anyone who has homeless people camping on their property is required to comply with the Human Fecal Material Discharge Prohibition. The County of Monterey and city officials prosecute incidents of illegal dumping. Complaints are investigated and financial rewards are given to anyone who helps identify offenders. Education and outreach programs are in place to help stop illegal dumping.
  • Evaluation of Implementation Progress: Implementation progress is evaluated according to water quality improvements and attainment of trackable implementation actions. Monitoring results and evaluations of implementation actions are reviewed every three years. After reviewing all reports, programs and evaluations, the Central Coast Water Board (CCWB)decides which actions need to be taken to achieve the TMDL numeric targets.
  • Timeline and Milestones: CCWB reviews will continue every three years and numeric targets must be achieved 13 years after the Office of Administrative Law approved the Fecal Coliform TMDL for the lower Salinas River basin. This timeline is an estimation. Nonpoint source polluters need to be identified within this time frame and additional provisions may be necessary if numeric targets are not achieved within the estimated time frame.
  • Economic Considerations: There are planning, implementation, inspection, monitoring and reporting costs associated with management practices for mitigating storm drain discharges, domestic animal discharges, homeless encampment discharges, and sewage collection and treatment spills and leaks. These costs have to be considered when pollution control measures are required. The CCWB is responsible for estimating and reporting how much these practices will cost each city. It's important however to note the reported costs are merely estimates and may not be accurate.

Monitoring

  • Monitoring Sites: Fecal Coliform testing must be performed in receiving waters and urban storm water outfall discharges. Fourteen water bodies have been proposed for monitoring locations. These include: Salinas River, Reclamation Canal, Salinas River Lagoon (North), Old Salinas River, Alisal Creek, Gavilan Creek (3 sites), Towne Creek, Natividad Creek, Santa Rita Creek, Tembladero Slough, Qauil Creek and Chualar Creek.
  • Frequency: To evaluate compliance, a minimum of five water quality samples must be analyzed in a 30 day period. Collection is done during the wet (January 1 – March 31) and dry (May 1 – September 30) seasons. Indicator bacteria concentrations have been elevated between January and March, and so the wet season was selected to maximize monitoring results for receiving waters locations. To identify the extent of fecal coliform concentrations from storm water drain discharges, samples are collected three storm events and two dry season flows. For stormwater outfalls, the wet season is October 15 – April 30, and the dry season is May 1 – October 14 when flow is present.
  • Responsible Parties: Responsible parties include the City of Salinas, the County of Monterey, Salinas Industrial WWTP, the Castroville Water District, the County of Monterey Regional group, and owners and operators of lands with domestic animals, lands used for illegal dumping and lands with homeless encampments. for some locations, responsible parties are expected to collaborate.

Monitoring Plan

The Central Coast Water Board will require fecal coliform monitoring in receiving waters to be performed by responsible parties. Fourteen reviewing water monitoring locations have been identified that will allow the Central Coast Water Board to evaluate attainment of the TMDL and allocations. Fecal coliform monitoring for urban stormwater outfall discharges is also proposed as storm drain sampling will assess the effectiveness of management measures but will not be used to determine if the TMDL is attained. Receiving water samples will be used to determine compliance.

Most waterbodies have more than one responsible party indicated for monitoring sites as multiple parties are probable or potential sources of controllable pathogen loads and share responsibility for monitoring. Responsible parties could collaborate in monitoring at these locations

Laws and Policies

The law which creates the TMDL process is the Clean Water Act(CWA). The CWA defines a TMDL as "a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet water quality standards, and an allocation of that amount to the pollutant's sources."

Future research

While fecal coliforms are useful indicators of pathogenic biological organisms they do not prove their presence/absence. As a result, future research needs to be focused on developing quick, cheap and efficient tests for a wide range of pathogenic organisms. This could be accomplished with the use of DNA chip technology, and or microarrays.

  • Possibly covered in the data analysis section.
is this section really needed?

References

  1. RWQCB, 2009, ...need full citation here...Total Maximum Daily Load for Fecal Coliform for the Lower Salinas River Watershed, Monterey County, California

Links

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.