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

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==Numeric Target==
 
==Numeric Target==
  
Numeric targets for FIB are established in the basin plan based on the designated beneficial uses of a given water body.  In the impaired waterbodies of the Lower Salinas watershed, the numeric targets of FIB for Water Contact Recreation, Non-Contact Recreation, and Shellfish Harvesting are being exceeded. As shellfish harvesting is likely to be eliminated as a beneficial use, the numeric target for this TMDL is 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 numeric target:
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Numeric targets for FIB are established in the basin plan based on the designated beneficial uses of a given water body.  In the impaired waterbodies of the Lower Salinas watershed, the numeric targets of FIB for Water Contact Recreation, Non-Contact Recreation, and Shellfish Harvesting are being exceeded. As shellfish harvesting is likely to be eliminated as a beneficial use, the numeric target for this TMDL is the water quality standard for Water Contact Recreation, which is the next most protective.  
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The goal is for all water bodies in the TMDL area to meet this numeric target:
 
*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.
 
*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.
  

Revision as of 10:54, 1 April 2010

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]. The summary was prepared 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 a Total Maximum Daily Load (TMDL) for Fecal Coliform for the Lower Salinas River Watershed in Monterey County, California. The final TMDL report was available as of 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 readily used to help identify water body contamination as a result of 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

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. When a water body fails to meet the minimum quality standards required for its beneficial uses (assigned purposes), a TMDL is established.

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 runs dry during the summer months, and in comparison the lower Reclamation Ditch flows year-round.

Problem Statement

The Lower Salinas River and eleven of its tributary water bodies are 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, of these water bodies do not meet the water quality objectives for the following beneficial uses (BUs):

  • 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 due to elevated concentrations of Fecal Indicator Bacteria (FIB). FIB indicate the presence of human pathogens, and are monitored because specific human pathogens are difficult and expensive to measure. There is some scientific uncertainty about the accuracy of FIB as a gauge for pathogen risk, but monitoring FIB is currently the most cost efficient and effective method present today.

FIB analyzed for this project consisted of fecal coliforms and Escherichia coli (E. coli) O157:H7. The presence of fecal coliform and E. coli were determined through water sample analysis using various methodologies. The Multiple Tube Fermentation (MTF) method and the Colilert method were utilized in testing for fecal coliforms. E. coli O157:H7 was tested for using the polymerase chain reaction (PCR), culture, and Pathatrix methods. The combination of these various methods indicated the magnitude of the pathogen problem, the potential presence of other fecal pathogens and the impairment of the water body.

This study required a qualitative and quantitative approach and various types of data were used. Spatial data were used to estimate roles of the various land uses around waterbodies. Data was therefore collected on streams, watershed boundaries, roads, land use and elevation and mapped using Geographic Information Systems (GIS) software. Conclusions based on the various water sampling sites and land use were made in order to identify likely sources for FIB. FIB concentration and presence data were also analyzed with respect to the dry and wet seasons. Conclusions were drawn on the effects of wet and dry weather and it was found that the rainy season produced higher observed FIB. USGS flow data were also incorporated in the study to estimate the load and assimilative capacity, and to derive daily load expressions. While this is not a necessary component for a TMDL, it is useful for informational purposes in accordance with USEPA guidance.

E. coli rain event data were collected from thirteen sites after two separate rain events, neither of which were first flush rain events. It was found that the median E.coli density was significantly higher during rain events (2,685 MPN/100mL) than non rain events (224 MPN/100mL). There were multiple identifications of E. coli O157:H7, mostly at the confluence of Gabilan Creek and Towne Creek in the northern part of the study area. E. coli O157:H7 identification coincided with pasture and shrubland use areas with generally large amounts of ranch land and animal activity.

Other assessed waterbodies for which data did not indicate impairment, or for which data were insufficient were:

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

Numeric Target

Numeric targets for FIB are established in the basin plan based on the designated beneficial uses of a given water body. In the impaired waterbodies of the Lower Salinas watershed, the numeric targets of FIB for Water Contact Recreation, Non-Contact Recreation, and Shellfish Harvesting are being exceeded. As shellfish harvesting is likely to be eliminated as a beneficial use, the numeric target for this TMDL is 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 numeric target:

  • 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. No explicit linkage analysis is given because the CCRWQCB expresses the intent to implement the TMDL based on a target concentration of fecal coliform rather than a load. However, under the 'TMDL Development' section of the TMDL report, methods are described to link target concentrations to loading capacity.

TMDL Development

The official TMDL objective is expressed as a numeric target concentration that applies to all impaired waterbodies in the lower Salinas River watershed. However, additional analysis links the target concentration to maximum allowable loads for each individual waterbody, 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]. The 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 <math> 2.8 x 10^{11} </math> (orgs/day). This goal represents an 89% reduction from the current estimated load of <math>2.62 x 10^{12}</math> (orgs/day).

The method described above is dependent on streamflow data. For ungaged streams, flow was estimated from measurements on comparable streams and adjusted 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 are complicated by tidal fluctuation.

Although the intent is to implement the concentration-based allocations and TMDLs, due to a court decision in Friends of the Earth, Inc. v. EPA, et al., No. 05-5015 (D.C. Cir. 2006),and the resulting U.S. EPA guidance, the following MPN/per day interpretation was provided as well [2].

"A TMDL is allocated into waste load allocations (WLAs) for point sources (NPDES permits; general permits), load allocations (LAs) for nonpoint sources (including background loads), and the margin of safety (MOS). The TMDL is the sum of the individual WLAs for point sources, and load allocations (LAs) for nonpoint sources and natural background levels. In addition, the TMDL must include a margin of safety (MOS), either implicitly within the WLA or LA, or explicitly, that accounts for uncertainty in the relation between pollutant loads and the quality of the receiving water body. Conceptually, this definition is denoted by the equation: <math>TMDL = (Sum) WLA + (Sum)LA + MOS</math>" [3].

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 specified in the TMDL report is for all controllable water sources to meet the target concentration. As a load-based approach was not adopted in the TMDL, no margin of safety was given.

Critical Conditions and Seasonal Variation

The TMDL report does not identify any "critical" environmental factors, in which a slight change could lead to exceedence of water quality objectives. However, it was noted that pollutant concentration is dependent on flow volume, which is often irregular in Monterey County. Also, localized areas of stagnant water with fine sediments foster bacterial growth and 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 because of the increased pathogenic risk related to human waste. Wasteload and load allocations for responsible parties associated as sources of fecal coliform for waterbodies 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 waterbodies in the project area cannot achieve the numeric targets required for coliform bacteria. The stakeholders added that some waterbodies are on private land, have other uses besides recreational and may be inappropriate for recreational use. Water flow on these lands is not always natural, especially during summer months when irrigation and groundwater pumping is used. Increased concentrations of the fecal indicator bacteria in these waterbodies may result from evaporation, and so the required numeric water quality objectives may be exceeded. 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. Point sources are a single identifiable localized source of pollution. Point sources of fecal coliform were identified as storm drain discharges to storm sewer systems and spills and leaks from sanitary sewer collection and treatment systems. Nonpoint sources are pollutants 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 describes an implementation and monitoring road map to identify key pollutants, record progress, and take action to obtain results. In accordance with National Pollutant Discharge Elimination System (NPDES) permitting rules, MS4 Stormwater Permit requirements and Nonpoint Source Implementation Program guidelines as requested by the CCRWQCB, pursuant to California Water Code Section 13267 or 13383, the responsible parties will submit reports to the CCRWQCB 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 CCRWQCB decides which actions need to be taken to achieve the TMDL numeric targets.
  • Timeline and Milestones: CCRWQCB 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. 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 CCRWQCB 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, Quail Creek and Chualar Creek. Five storm drain monitoring sites were selected.
  • Frequency: To evaluate compliance, receiving waters will be monitored with a minimum of five water quality samples within one 30 day period. One collection is done during the wet (January 1 – March 31) and one during the dry (May 1 – September 30) seasons. To identify the extent of fecal coliform concentrations from storm water drain discharges, samples will be collected in 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.


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."


References

  1. Rose C, Osmolovsky P, Harlan L. 2010. Regional Water Qualtiy Control Board Central Coast Region. Available from:Total Maximum Daily Load for Fecal Coliform for the Lower Salinas River Watershed, Monterey County, California
  2. United States Court of Appeals <http://www.ll.georgetown.edu/federal/judicial/dc/opinions/05opinions/05-5015a.pdf>April 2006.
  3. TMDL Report<http://www.waterboards.ca.gov/centralcoast/board_info/agendas/2010/mar/item_12/att_2.pdf>February 2010. Pg 159

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.