Difference between revisions of "TMDL for Fecal Coliform for the Lower Salinas River Watershed, Monterey County, California"

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(Water Quality Objectives)
(Data Analysis)
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*Snap Shot Day monitoring program (Monterey Bay National Marine Sanctuary Citizen Watershed Monitoring Network)  
 
*Snap Shot Day monitoring program (Monterey Bay National Marine Sanctuary Citizen Watershed Monitoring Network)  
  
'''Problems with water sample tests'''
 
 
There is scientific uncertainty about whether FIB is an effective indicator of pathogen risk due to nonpoint sources and what the environmental sources of FIB are.  Additional limitations of FIB include: 1) their presence only means that human pathogens may be present not necessarily that they are present; 2) the survival levels in the environment may vary between FIB and the pathogens for which they are the indicators; and 3) these indicators do not fully assess the human health risk from human enteric viruses and other human specific pathogens as the FIB are not human-specific.
 
There is scientific uncertainty about whether FIB is an effective indicator of pathogen risk due to nonpoint sources and what the environmental sources of FIB are.  Additional limitations of FIB include: 1) their presence only means that human pathogens may be present not necessarily that they are present; 2) the survival levels in the environment may vary between FIB and the pathogens for which they are the indicators; and 3) these indicators do not fully assess the human health risk from human enteric viruses and other human specific pathogens as the FIB are not human-specific.
  
Most E. coli strains are harmless and reside naturally in the intestines of humans and animals with only some being strains being pathogenic.  The pathogenic E. coli O157:H7 strain produces a powerful toxin that can cause severe illness and death and its presence in water is an indication of recent sewage or animal waste contamination.  In addition, the presence of E. coli O157:H7 indicates not only that a pathogenic E. coli is present, but also indicates the potential presence of other pathogenic organisms.
+
The potential presence of fecal coliform and ''Escherichia coli''(''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 with only some being strains being pathogenic.  The pathogenic E. coli O157:H7 strain produces a powerful toxin that can cause severe illness and death and its presence in water is an indication of recent sewage or animal waste contamination.  In addition, the presence of E. coli O157:H7 indicates not only that a pathogenic E. coli is present, but also indicates the potential presence of other pathogenic organisms.
  
 
  ...What are the indicators? How did they come up with the numbers?...
 
  ...What are the indicators? How did they come up with the numbers?...

Revision as of 23:08, 21 March 2010

An 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 [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.

This report investigates the impairment of the Lower Salinas River and several of its tributaries as a result of increased fecal coliform concentrations in accordance with 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 Canal2
  • Gabilan Creek
  • Alisal Creek
  • Natividad Creek
  • Santa Rita Creek
  • Quail Creek
  • Chualar Creek
  • Towne Creek

The biological impairment of a river can result from microbial pathogens (viruses, protozoa's, and bacteria) that can be readily correlated with fecal coliforms. Fecal coliforms function as indicator species, known as fecal indicator bacteria (FIB), that are used to identify water body contamination from other pathogenic organisms harmful to humans.

Each water body is used for specific purposes (or beneficial uses). When waters don’t meet the minimum quality standards required for those designated uses, TMDL criterion is applied. The Lower Salinas watershed is used for a variety of purposes including, but not limited to: groundwater recharge, wildlife habitat, industrial and agricultural supplies, commercial and recreational fishing and recreational activities. Understanding water body impairment due to microbial pathogens is important for human health and safety as well as achieving environmental sustainability.

Watershed Description

The area of concern for this TMDL is the lower 400 square miles of the Lower Salinas Valley and includes two major watersheds, the Reclamation Canal and Lower Salinas River. The Reclamation Canal watershed drains into the Old Salinas River and includes Tembladero Slough and its tributaries, while the Lower Salinas Watershed drains into the Salinas River Lagoon and includes Blanco Drain, Toro Creek, Quail Creek, Chular Creek and other tributaries of the Salinas River. While there is some hydrologic connectivity between the two, it is limited. A slide gate at the northwest end of the Salinas River Lagoon which allows periodic drainage into the Old Salinas River is closed in the winter to prevent flooding in the surrounding agricultural lands. The breached sandbar at the mouth of the lagoon discharges inflow from the Salinas Lagoon directly into the Monterey Bay. The project area boundaries are the Gabilan Range to the east, the Sierra de Salinas range to the west, and the Monterey Bay to the north east.
TMDL Project Area

Surface waters 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.

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 safety criteria for the following designated beneficial uses:

  • Water contact recreation.
  • Non-contact water recreation.
  • Shellfish harvesting for human consumption (under review).

Water Quality Objectives

Water quality objectives that apply to indicator bacteria are based on designated beneficial uses. For water contact recreation, 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. For non-contact water recreation, the total coliform concentration for a minimum of five samples in any 30 day period should not exceed a log mean of 2000 per 100 ml, or 4000 per 100 ml for 10% of total samples in any 30 day period. For shellfish harvesting, the median total coliform concentration in a water column for any 30-day period should not exceed 70 per 100 ml, or 230 per 100 ml for 10% of the total samples in any 30-day period for a five-tube decimal dilution test, or 330 per 100 ml for a three-tube decimal dilution test. The shellfish harvesting beneficial use is being reassessed and water quality standards for this use may be addressed in a separate TMDL listing.

When the total coliform concentration exceeds the minimum requirements, a water body is considered impaired. However, in order to place it on the impaired list, each site must exceed these minimum contaminant levels a designated number of times depending on sample size. For example, for a sample size of 55-60, 10 exceedances are needed to assert impairment. For a sample size of 116-121, 20 exceedances are needed to assert impairment of the water body.

The EPA designates the TMDL criteria and updates it regularly as new research is published that addresses human health concerns associated with coliform bacteria contamination. The following table lists recommendations for human health safety in recreational waters.


USEPA recommended criteria for E. coli.

Indicator: E. coli

Risk Level: 8

Single Sample Maximum Allowable Density (per 100 mL) Geometric Mean Density (per 100 mL): 126

Designated Beach Area (75th percentile): 235

Moderate Full Body Contact Recreation (82nd percentile): 298

Lightly Used Full Body Contact Recreation (90th percentile): 409

Infrequently Used Full Body Contact Recreation (95th percentile): 575

Data Analysis

Water Samples The Salinas River watershed is listed as impaired due to fecal coliforms. Fecal indicator bacteria (FIB) are monitored instead of pathogens because direct measurements of pathogens are thought to be too slow, difficult and expensive.

Data sources for the TMDL came from:

  • TMDL Project data set
    • From TMDL Project and USDA
  • Central Coast Ambient Monitoring Program (CCAMP)
  • Entities regulated by the Central Coast Water Board (City of Salinas Stormwater Program)
  • Central Coast Watershed Studies (CCoWS) Team (affiliated with the Watershed Institute at California State University-Monterey Bay)
  • Snap Shot Day monitoring program (Monterey Bay National Marine Sanctuary Citizen Watershed Monitoring Network)

There is scientific uncertainty about whether FIB is an effective indicator of pathogen risk due to nonpoint sources and what the environmental sources of FIB are. Additional limitations of FIB include: 1) their presence only means that human pathogens may be present not necessarily that they are present; 2) the survival levels in the environment may vary between FIB and the pathogens for which they are the indicators; and 3) these indicators do not fully assess the human health risk from human enteric viruses and other human specific pathogens as the FIB are not human-specific.

The potential presence of fecal coliform and Escherichia coli(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 with only some being strains being pathogenic. The pathogenic E. coli O157:H7 strain produces a powerful toxin that can cause severe illness and death and its presence in water is an indication of recent sewage or animal waste contamination. In addition, the presence of E. coli O157:H7 indicates not only that a pathogenic E. coli is present, but also indicates the potential presence of other pathogenic organisms.

...What are the indicators? How did they come up with the numbers?...

Source Analysis

Sources of fecal coliform in the Lower Salinas Watershed were identified to arise from various sources. These included:

  • Point Sources - a single identifiable localized source of pollution (i.e. you know exactly where the pollution is coming from and can quantify it).
    • Storm drain discharges to storm sewer systems
    • Spills and leaks from sanitary sewer collection and treatment systems
    • concentrated animal feeding operations and dairies
  • Nonpoint Sources- pollution derived from many different diffuse sources (i.e. regulation of one point or source will not rectify the problem).
    • 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
    • Non-controllable natural sources (wind-borne debris)

Numeric Target

The TMDL for fecal coliform is designed to acheive a concentration where the log mean over any 30 day period does not exceed 200 MPN per 100 mL, and no more than 10 percent of samples exceed 400 MPN per 100 mL.

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.

TMDL Development

The TMDL for fecal coliform is 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 are 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 compared to existing loads derived from field data to determine where exceedences are greatest or most frequent.

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 our climate. Also, localized areas of stagnant water with fine sediments are favorable for bacteria propagation, and may increase concentrations of Fecal Indicator Bacteria.

TMDL Allocations

Allocations are given as target concentrations. For non-human fecal indicator bacteria, all allocations are the same as the target concentration stated above. The allocation for human FIB is zero. Load-based allocations, based on the method described in the 'TMDL development' section above, are also given in Table 7-7 of the TMDL report.

Public Participation

There are many stakeholders in the Lower Salinas Watershed that are 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

Implementation and Monitoring

The goal of implementation and monitoring is to reduce pathogen loads and achieve the stated TMDLs for the Salinas River Watershed. Potential pathgoen sources include: municipal storm drain discharges, domestic animal/livestock discharges, illegal dumping, discharges from homeless persons/encampments, sanitary sewer collection system spills and leaks, wildlife, and sediment bedoad resuspension. Because of the complexity involved with coordinating all these various sources for patholgoical pollutants the report lays out an implementation and monitoring road map to identify key aspects, and make sure progress is recorded and results obtained.

Implementation

  • Implementation Actions
  • Evaluation of Implementation Progress
  • Timeline and Milestones
  • Economic Considerations

Monitoring

  • Monitoring Sites
    • Frequency
    • Responsible Parties

Monitoring Plan

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.

References

  1. 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.