Difference between revisions of "TMDLs in the Monterey Bay Region of California"

Revision as of 22:17, 31 March 2014

This page summarizes the development and implementation of Total Maximum Daily Load (TMDL) plans in the Monterey Bay Region of California. The page was created by the ENVS 560/L Watershed Systems class at CSUMB.

Background

Under 1987 provisions (section 304 (1)) to the Clean Water Act of 1972, states must identify and report all water bodies which do not meet water quality or beneficial use standards. Those impaired (polluted) water bodies not meeting water quality standards must be placed on the 303d list.

States must submit updated lists every two years. Along with identification of impaired water bodies, states must also identify stressors causing the impairment (i.e. pollutants), which are also identified on the 303d list. A remediation plan must then be developed and implemented for each impaired water body listed.

These plans are known as total maximum daily loads (TMDLs). TMDLs are used to define and achieve a total maximum daily load for each pollutant causing impairment within a water body. The list also identifies where a TMDL has been approved by the Environmental Protection Agency (EPA) and implementation is available, but water quality standards have not yet been met, or an action other than a TMDL is being used to address the issue.

Central Coast 303d list documents

The 303d list for the Central Coast region of California (Region 3) is maintained by the Central Coast Regional Water Quality Control Board. The 2006 303(d) list for the Central Coast region is available as a .pdf or .xls file^[1][2]. The 2010 303(d) statewide list is available as an .xls file^[3]:

• Category 1. All core uses are supported;
• Category 2. At least one core use is supported;
• Category 3. Insufficient information exists to make a determination;
• Category 4A. At least one core use is not supported, however "a TMDL has been developed and approved by USEPA and is reasonably expected to result in the attainment of the water quality standard within a reasonable, specified time frame (p.10, CCRWQCB)."
• Category 4B. At least one core use is not supported, however "an existing regulatory program is reasonably expected to result in the attainment of the water quality standard within a reasonable, specified timeframe (p.10, CCRWQCB)."
• Category 5. At least one core use is not supported. A TMDL needs to be developed.

Monterey Bay area listings

The closest listings to Monterey Bay include: ^[4]

For more details, see:

• Monterey Bay Area TMDL Listings and
• Monterey Bay Area TMDL Listings - Priorities, Progress, and Documents

Approaches to nutrient TMDL development are in the following reports:

• The Chorro Creek Nutrient TMDL report set a sodium concentration limit of 50 mg/L and total dissolved solids concentration of 500 mg/L in order to help achieve the water quality objective for nutrient concentrations.

• The Pajaro River and Llagas Creek report sets the maximum concentration for nitrate within the water body at 10mg/L in order to protect beneficial uses. The report does not include seasonality because the TMDL is equal to the water quality objectives of the region.

• The San Diego Creek and Newport Bay Report set the nitrate TMDL according to different seasons. It allows 224 lbs/day of total inorganic nitrogen in Reach 2 of San Diego Creek from October 1 to March 31, and 175 lbs/day from April 1 to September 30.

Placeholder area (move into appropriate section or article)

Numeric targets are concentrations of specified nutrients that would not impair designated beneficial uses of a given water body. Water quality objectives given in the Basin Plan ^[5]. Water quality objectives for the Basin Plan are attempts to quantify the allowable nutrient concentrations. Objectives listed in the Plan are used as a starting point during TMDL development and adoption.

Margin of safety (MOS)

The margin of safety in the Monterey Bay region compares to other regions as being (more/less/equally?)… in terms of assumptions made of the environmental system.

Some examples of reports that used conservative estimates include:

• Pajaro River and Llagas Creek TMDL report
• Chorro Creek TMDL Report
• San Diego Creek TMDL report

The San Louis Obispo Creek TMDL Report used the quantitative approach and estimated the margin of safety to be about 20% of the total nitrate-N mass load based on a number of uncertainties and limitations in their data.

The Malibu Report Malibu Creek watershed TMDL report also estimated a 20% margin of safety and implicitly included conservative assumptions into the TMDL analysis. However, it is this TMDL report has not yet been approved on the state or federal level (UPDATE FOR 2012).

Implementation

Several approaches to specifying a monitoring plan have been adopted in federally approved TMDLs in the Monterey Bay area

Examples of approaches to implementation found in similar regional TMDL reports

• Laguna de Santa Rosa Nutrient TMDL: the Waste Reduction Strategy includes: a grant program aimed at reducing waste inputs from confined animal operations, a storm water runoff program, an NPDES permit program, and voluntary actions organized by the Laguna Watershed Coordinated Resource Management and Planning Task Force.
• San Luis Obispo Creek Nutrient TMDL: the NPDES permit for the City of San Luis Obispo will incorporate an effluent limit for their NPDES permit, regulations for storm water through a small MS4 permit, cropland nitrate sources will be regulated and monitored through the Ag Waiver.
• Santa Clara River Nitrogen TMDL: Ammonia, nitrite, and nitrate reductions will be regulated through denitrification upgrades to Publicly Owned Treatment Works (POTW) and enforcement of effluent limits, NPDES permits, and agricultural Best Management Practices.

Examples of TMDLs

The Lower Salinas River Watershed Nutrient TMDL Progress Report has summarized procedures to develop numeric targets for nutrient loading reductions (see above) in impaired water bodies, but did not provided recommended LAs. TMDLs in other parts of California provide examples of different approaches used to set TMDL allocations:

• The Nitrate TMDL in development for the Pajaro River and Llagas Creek sets all nitrate allocations (including background levels) at the numeric target of 10mg/L.
• The Lower Salinas River Watershed Fecal Coliform TMDL Final Report sets allocations that are either equal to the TMDL or zero.
• The TMDL for Nutrients in San Diego Creek and Newport Bay used by the EPA as an example for a nutrient TMDL sets allocations based on mass, but sets two different allocations for each source based on high and low water flow conditions.
• The Santa Clara River Nitrogen TMDL gives allocation to water reclamation plants, publicly owned treatment works, and non point sources based on daily mass. Individual allocations for non-point sources are not specified.

References

1. ↑ CCRWQCB. http://www.waterboards.ca.gov/water_issues/programs/tmdl/docs/303dlists2006/epa/r3_06_303d_reqtmdls.pdf 2006 CWA Section 303(d) List of Water Quality Limited Segments Requiring TMDLs (Central Coast Region)
2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named List_of_Water_Quality_Limited_Segments_Requiring_TMDLs
3. ↑ Central Coast Regional Water Quality Control Board. 2009. Clean water act sections 305(b) and 303(d) integrated report for the Central Coast region. Public review draft April. http://www.swrcb.ca.gov/centralcoast/water_issues/programs/tmdl/303d/2008_0409_draft_integrated_report.pdf
4. ↑ http://www.waterboards.ca.gov/water_issues/programs/tmdl/docs/303dlists2006/epa/state_06_303dlist.xls List of Water Quality Limited Segments Requiring TMDLs.
5. ↑ [1].

Links

• Central Coast Region Agricultural Waiver
• TMDL
• TMDL for Fecal Coliform for the Lower Salinas River Watershed, Monterey County, California
• TMDL for Nutrients in Lower Salinas River Watershed, Monterey County, California
• TMDL for Chlorpyrifos and Diazinon in Lower Salinas River Watershed, Monterey County, California
• Table of 303d Listed Waters in Monterey Bay Region
• ENVS 560/L Watershed Systems class

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.