TMDL for Nutrients in Lower Salinas River Watershed, Monterey County, California
This summary article on Total Maximum Daily Load for Nutrients in the Lower Salinas River Watershed (LSRW), Monterey County, California is built from information taken from the Regional Water Quality Control Board Central Coast Region progress report, 2006 TMDL report, and preliminary draft report[1] (2012) on Total Maximum Daily Load for Nutrients for the LSRW.
This summary is an ongoing project, with updates and changes made periodically by the ENVS 560/L Watershed Systems class at CSU Monterey Bay (CSUMB).The TMDL for nutrients for the LSRW has been revised many times in recent history, 2006, 2010, and most recently, a preliminary draft project report (2012) for the LSRW and the Moro Cojo Slough subwatershed.
Contents
Project definition
The California Regional Water Quality Control Board for the Central Coast Region (CCRWQCB) has developed a 2012 draft TMDL project report for nutrients in the Lower Salinas River Watershed (LSRW) (Monterey County, CA)[1]. The draft report is titled: Lower Salinas River and Reclamation Canal Basin, and the Moro Cojo Slough Subwatershed, Monterey County, California. Nutrients are defined as biologically-accessible nitrogen compounds and orthophosphate loading into waterways of the LSRW. Interestingly, though orthophosphate is identified as part of the TMDLs, the draft indicates no waterbodies as being orthophosphate-impaired.
This draft report indicates a proposed geographic scope of around 405 acres in the Lower Salinas Valley of northern Monterey County, focused on the two major drainages, the Reclamation Canal Drainage and the Lower Salinas River Drainage (pictured at right). Subwatersheds identified include the Moro Cojo subwatershed.
The ultimate receiving body (drainage) of both waterways and their tributaries is Moss Landing harbor. Pollutants addressed by the proposed TMDL draft (2012) are nitrate, un-ionized ammonia, and orthophosphate. Reductions in pollutants are expected to target 303(d)-listed impairments from low dissolved oxygen (DO) and chlorophyll a within the project area. These impairments relate to the "biostimulatory" effects of nitrate and orthophosphate impairment.
![](/wiki/images/thumb/f/f1/Majordrain_TMDL_projarea.png/325px-Majordrain_TMDL_projarea.png)
These pollutants are of concern because of their direct and indirect detrimental effects to the freshwater aquatic habitat, drinking water (groundwater) and the environment of the receiving water body. The CCRWQCB presented a progress report in June 2010 that contains background information, provisional nutrient targets, and a compilation of water quality data for water bodies in the region. The 2010 progress report identifies potential nutrient load sources. A draft source analysis portion of the TMDL project is available from the 2012 draft TMDL document[1] (UPDATE).
The TMDL for nutrients in the LSRW project (2012) has addressed the nutrient-related impairments in the Lower Salinas River watershed water bodies listed under the section 303 (d) of the Clean Water Act (CITE). The 2010 303(d) List of Impaired Waterbodies is the current and active list for the California Central Coast. In 2010, the CCRWQCB presented an updated list in its 2010 Integrated Report, but this report has not yet been approved by the US EPA[2].
The following table contains water bodies and nutrient-related justification for listing in the 2006, 2010, and 2012 (unapproved draft) impairment list:
(No data reported past March 2010)
Water Body | 2006 Listed Impairment | 2010 Listed Impairment | 2012 Listed Impairment (Proposed) |
---|---|---|---|
Alisal Creek | Nutrient | Chlorophyll-a, Nitrate | Ammonia (Un-ionized), Chlorophyll-a |
Alisal Slough | Not Listed | Low Dissolved Oxygen, Nitrate | Low Dissolved Oxygen, Nitrate (biostimulatory*) |
Blanco Drain | Not Listed | Low Dissolved Oxygen, Nitrate | Low Dissolved Oxygen, Nitrate (biostimulatory) |
Chualar Creek | Not Listed | Ammonia (Un-ionized), Nitrate | Nitrate (drinking water) |
Esperanza Creek | Not Listed | Nitrate | Nitrate (drinking water), (NO DATA on un-ionized ammonia) |
Espinosa Slough | Not Listed | Ammonia (Un-ionized), Nitrate | Ammonia (Un-ionized), Nitrate (drinking water) |
Gabilan Creek | Nitrate | Ammonia (Un-ionized), Nitrate | Nitrate (drinking water) |
Lower Reclamation Canal | N/A | N/A | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate (biostimulatory) |
Lower Salinas River | N/A | N/A | Nitrate (biostimulatory) |
Merrit Ditch | Not Listed | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate (biostimulatory) |
Moro Cojo Slough | Ammonia (Un-ionized), Low Dissolved Oxygen | Ammonia (Un-ionized), Low Dissolved Oxygen | Ammonia (Un-ionized), Low Dissolved Oxygen |
Natividad Creek | Nitrate | Ammonia (Un-ionized), Low Dissolved Oxygen | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate (biostimulatory) |
Old Salinas River | Not Listed | Chlorophyll-a, Low Dissolved Oxygen, Nitrate | Chlorophyll-a, Low Dissolved Oxygen, Nitrate (biostimulatory) |
Old Salinas River Estuary | Ammonia (Un-ionized), Low Dissolved Oxygen, Nutrients | Nutrients | N/A (not in 2012 report?) |
Quail Creek | Nutrients | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate | Ammonia (Un-ionized), Nitrate (drinking water) |
Salinas Reclamation Canal | Ammonia (Un-ionized), Low Dissolved Oxygen | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate (biostimulatory) |
Salinas River (lower, estuary near Gonzales Rd. Crossing) | Nitrate, Nutrients | Nitrate | Nitrate (biostimulatory) |
Salinas River Lagoon (North) | Nutrients | Nutrients | N/A (not in 2012 report?) |
Santa Rita Creek | Nitrate | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate | Ammonia (Un-ionized), Low Dissolved Oxygen, Nitrate (drinking water) |
Tembladero Slough | Ammonia (Un-ionized), Nutrients | Chlorophyll-a, Nitrate, Nutrients | Chlorophyll-a, Nitrate (biostimulatory), Nutrients |
- Nitrate is divided into "biostimulatory" impairment concentrations and drinking water impairment concentrations of 1.7-6.4 and 10 mg/L respectively.
TMDL for nutrients development status for the LSRW
![](/wiki/images/thumb/4/43/TMDL_Impairment_Map.png/275px-TMDL_Impairment_Map.png)
(expand..)
The nutrient TMDL for the Lower Salinas River watershed has been completed for 2010 and is in proposed development stages for 2012 (as of April). The CCRWQCB progress report summarized the process to date and established preliminary and provisional numeric targets to be included in the TMDL (see Numeric Targets above).
TMDLs establish the concentration or daily load of nutrients a body of water can contain while continuing to support its defined beneficial uses. TMDLs can be defined in terms of a mass load or can be set as a unit of concentration. Defining a unit of concentration may be a useful approach for the Lower Salinas River Watershed. During TMDL development, it is necessary to consider secondary indicators, such as dissolved oxygen levels, transparency and algal biomass, that are linked to the beneficial uses for the water body. A modelling tool can be used to link secondary indicators to concentrations in the water column and predict levels of nutrients that would impair specific beneficial uses. Some approaches to nutrient TMDL development can be found 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 concentations
- 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 it 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. They allow 13 lbs./day of inorganic nitrogen for reach 2,224 lbs./day from October 1 to March 31 total nitrogen and 175 lbs./day from April 1 to September 30.
TMDL for Nutrients in the LSRW (data analysis)
The June 2010 California Regional Water Board Nutrient TMDL Progress Report acknowledges that the presence of excess nutrients does not directly impair waterways, rather, indirect impacts associated with the presence of excess nutrients diminish beneficial uses of waterways.
Secondary indicators of eutrophication ("biostimulation") such as nuisance algal blooms, drastic diel swings in dissolved oxygen concentrations, and loss of habitat must also be monitored and documented as they are more directly linked to the beneficial uses of waterways than nutrient concentrations alone.
Data analysis for the June 2010 California Regional Water Board Progress Report included:
- A delineation of watershed boundaries
- A list of subwatersheds
- Stream classification, which revealed in general low gradient streams on the valley floor were perennial, and many headwater streams tended to be ephemeral.
- An assessment of groundwater as baseflow. For the TMDL project area baseflow index values for groundwater ranged from 38 to 26 percent.
- An assessment of mean groundwater nitrate concentrations for the project area. Values reported ranged from 0.1-10.0 mg/l to 100.1-200.0 mg/l of nitrate.
- An assessment of mean annual precipitation for the project area. For the project area values ranged between 11.1 inches to 33.5 inches on average annually.
- An analysis of land use and land cover. In the project area, land uses include approximately 34% farmland, 31% grazing land, 8% urban, and 26% undeveloped/forested/restricted.
Critical Conditions and Seasonal Variation
The TMDL progress report did not address the “critical” environmental factor for nutrient loading in the Lower Salinas River Watershed, in which a slight change could lead to exceeding the water quality objectives (ELABORATE...). However, the progress report does specify some indicators that can impair the beneficial uses of the regional water bodies.
Previous TMDLs in the Monterey Bay Region of California have not included critical conditions, however critical conditions for a Nutrient TMDL may be advisable due to the high occurrence of nutrient loading for agriculture in the Salinas Valley. The 2003 Santa Clara River Nitrogen TMDL included critical conditions. Although the climate around the Santa Clara River is drier, that water body is similar to the Lower Salinas River in seasonal flow and the effects of the first large storm ("first-flush").
Although not an ideal approach, the Santa Clara River TMDL makes an attempt to incorporate the increased impairment hazard presented by seasonal variation [3]. Specifically, critical conditions were evaluated on the basis of those conditions that would cause an increase in inorganic nitrogen species due to either (1) low flow conditions, (2) the effects of the first big storm of the season (first flush), or, (3) rising groundwater effects.
General overview of TMDL development process for the LSRW
![](/wiki/images/thumb/9/9a/TMDL_development.jpeg/250px-TMDL_development.jpeg.png)
TMDL development involves many stages from problem identification and problem statement development, through development of numeric standards to restore water quality goals, source assessments and linkage analysis, to load allocations, monitoring/evaluation, and finally implementation.
Problem Statement
According to the draft TMDL report (2012):
"Discharges of nitrogen compounds and orthophosphate are occurring at levels in surface waters which are impairing a wide spectrum of beneficial uses and, therefore, constitute a serious water quality problem. The municipal and domestic drinking water supply (MUN, GWR) beneficial uses and the range of aquatic habitat beneficial uses are currently impaired; potential or future beneficial uses of the agricultural irrigation water supply (AGR) for sensitive crops may be impaired. A total of 34 waterbody/pollutant combinations are impaired due to exceedances of water quality objectives. The pollutants addressed in this TMDL are nitrate, un-ionized ammonia, and orthophosphate. Orthophosphate is included as a pollutant due to biostimulatory impairments of surface waters. Reducing these pollutants is also anticipated to address several 303(d)-listed dissolved oxygen and chlorophyll a impairments in the TMDL project area. As a result of these conditions, beneficial uses are not being protected." and
"By developing TMDLs for the aforementioned pollutants, the water quality standards violations being addressed in this TMDL include:
- Violations of drinking water standard for nitrate
- Violations of the Basin Plan general toxicity objective for inland surface waters and estuaries (violations of un-ionized ammonia objective)
- Violations of the Basin Plan narrative general objective for biostimulatory substances in inland surface waters and estuaries (as expressed by excessive nutrients, chlorophyll a, algal biomass, and low dissolved oxygen)"
According to the CCWRQCB draft TMDL nutrient report (2012):
"There does not appear to be a significant geologic reservoir in the project area that could contribute to elevated nitrogen loads to surface waters."
Eutrophication of waterways may occur when excess nutrients are present and environmental conditions promote algal growth. Biologically-accessible nitrogen and phosphorus are limiting nutrients in many ecosystems (CITE). In general, sources of nutrients in watersheds include: urban runoff, fertilizers, groundwater, livestock, wastewater treatment plants, and septic systems. Specifically for the Lower Salinas River Watershed (Anderson et al. 2003) [5] identified irrigated agriculture as the dominant source of nutrients in watersheds in the region.
According to the SWRCB-contracted UC Davis report[6] (Harter and Lund 2012) on nitrate in California's Drinking Water for the State Water Resources Control Board (SWRCB), nitrates are reducing quality of drinking water from shallow wells. The report concludes that: "Most nitrate in drinking water wells today was applied to the surface decades ago."
The report is part of a contracted study for the SWRCB as part of the Senate-mandated Groundwater Nitrate Project as part of biannual reporting on initial studies into nitrate effects on drinking water in the Tulare Basin and Salinas Valley. The report also cites agriculture as the estimated source of 96% of nitrate loading to groundwater--200 Gg/yr (1 Gg = 1100 tons) within these regions, with the next largest (estimated) source (wastewater treatment and food processing wastes) loading 3.2 Gg nitrate/yr to groundwater.
Beneficial uses of waterways and water quality objectives are vital to determining water quality standards and goals.
Beneficial Uses (BUs) Associated with Waterways Listed for Nutrient Impairments
- Municipal and Domestic supply (MUN)
- Agriculture (AGR)
- Industrial Process (PRO)
- Industrial Service (IND)
- Ground Water Recharge (GWR)
- Water Contact Recreation (REC1)
- Non-Contact Water Recreation (REC2)
- Cold Freshwater Habitat (COLD)
- Warm Freshwater Habitat (WARM)
- Estuarine Habitat (EST)
- Wildlife Habitat (WILD)
- Rare, Threatened, or Endangered Species (RARE)
- Migration of Aquatic Organisms (MIGR)
- Spawning, Reproduction, and/or Early Development (SPWN)
- Biological Habitats of Special Significance (BIOL)
- Shellfish Harvesting (SHELL)
- Commercial and Sport Fishing (COMM)
- Freshwater replenishment (FRESH)
Waterbody | MUN | AGR | PRO | IND | GWR | REC1 | REC2 | WILD | COLD | WARM | MIGR | SPWN | BIOL | RARE | EST | FRESH | COMM | SHELL |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Old Salinas River Estuary | X | X | X | X | X | X | X | X | X | X | X | X | ||||||
Salinas River Lagoon (North) | X | X | X | X | X | X | X | X | X | X | X | X | ||||||
Tembladero Slough | X | X | X | X | X | X | X | X | X | |||||||||
Espinosa Slough | X | X | X | X | X | |||||||||||||
Salinas Reclamation Canal | X | X | X | X | X | |||||||||||||
Alisal Creek | X | X | X | X | X | X | X | X | X | X | ||||||||
Blanco Drain | X | X | X | X | X | |||||||||||||
Salinas River, down stream of Spreckels Gage | X | X | X | X | X | X | X | X | X | |||||||||
Salinas River,Chualar to Spreckles | X | X | X | X | X | X | X | X | X | X | X | X | ||||||
Quail Creek | X | X | X | X |
A more complete table of beneficial uses will be available in the final project report.
Numeric Targets
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 [7]. 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.
The water quality objective for nitrogen for the beneficial use MUN (defined above) is 10 mg/L. Currently, the numeric targets for nitrogen in the Lower Salinas River watershed are being developed. CCRWQCB staff prepared a progress report that summarized the development of provisional and preliminary numeric targets for total nitrogen.
The progress report described that one uniform nutrient target may not be sufficient in light of the large variability of stream morphology and hydraulics in the waterbodies contributing to the Lower Salinas River. The report explored a variety of ways to define a range of numeric targets. Final nutrient targets can be developed based on either calculations or estimations. The percentile based approach calculates the numeric target by using either the 25th percentile of nutrient data from reference streams or the 75th percentile of all nutrient data for the project area streams. The nutrient numeric endpoints (NNE) approach estimates in-stream benthic algal response to ambient stream conditions.
Based on these approaches, the provisional and preliminary numeric targets for total nitrogen listed in the progress report range from 1.4-2.2 mg/L depending on waterbody type. That range is consistent with established nutrient TMDLs on Malibu Creek and Rainbow Creek in Southern California.
Source Analysis
A draft source analysis for nutrients in the Lower Salinas River watershed has not been completed as of March 2012. The report uses STEPL (Spreadsheet Tool for Estimating Pollutant Load) to calculate nutrient loads (nitrogen and phosphorus--N and P) from various characteristics including watershed area, and nutrient loads (based on land use and land cover--LULC). These estimates are made at the project-area scale (405 acres), and can be recalculated for individual subwatersheds. The report cites a 1999 US EPA report and states, "both nitrogen and phosphorus reach surface waters at an elevated rate as a result of human activities."
This analysis reports estimates for urban annual N Load (lb/yr) and P Load (lb/yr) at 138,391 and 21,796 respectively.
Cropland estimates of N and P loading at 2,211,230 and 629,492 lbs/year by far made up the greatest proportion of source loads identified in the project area. Total N and P loading (lbs/year) were 2,911,676 and 793,236 respectively. This means that agriculture represents 76% of N and 79% of P loading in the area.
Grazing (209,521; 123,412) and forest (27,649; 11,327) also make contributions as well.
Because shallow groundwater acts as a reservoir for elevated concentrations of nitrogen and phosphorus in the regionCite error: Closing </ref>
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tag suggested steps:
- identify key questions
- evaluate monitoring options and
- implement the monitoring program.
The protocol document suggests that monitoring plans describe the timing, location, responsible parties, and quality assurance and control procedures.
The level of rigor required for a monitoring plan is dependent on confidence in the TMDL analysis. A greater level of uncertainty requires more rigorous monitoring actions and must allow room for future revision. Since watershed process drivers are not identical before and after implementation, models are useful for evaluating results of monitoring. Models can be calibrated to pre or post-implementation to better compare results of monitoring actions. Coordination with other existing or planned monitoring activities can be particularly helpful for long-term monitoring programs, large study areas, or if the water quality agency’s monitoring resources are limited. It is also important to choose the type of monitoring that will be most appropriate to yield desired goals and then develop a quality assurance plan to ensure the data can support future analysis.
Overall a monitoring plan is created to evaluate the effectiveness of the implementation strategies and TMDL elements such as numeric targets and pollutant estimates.
Examples of key questions:
- Are selected indicators capable of detecting impacts to designated use and responding in a measurable way to control actions?
- Have baseline or background conditions been adequately characterized?
- Are numeric targets set at levels that reasonably promote desired water quality for designated uses of concern?
- Have important pollutant sources been identified?
- Have important pollutant sources been accurately estimated?
Examples of approaches to monitoring found in similar regional TMDL reports
- Pajaro/Llagas Creek Nutrient TMDL: Follow-up monitoring data on Nitrate will be provided by the Monitoring and Reporting Program in the Ag waiver. Water Board staff will review data every three years. Additional monitoring will assess causes of excessive algae and low dissolved oxygen conditions that lead to impairment of water bodies.
- San Luis Obispo Creek Nutrient TMDL :The City of San Luis Obispo required to monitor effluent from the Water Reclamation Facility (WRF)in accordance with the NPDES permit. Cropland monitoring is consistent with the Ag Waiver. Regional Water Board Staff will review the results every three years.
- Santa Clara River Nutrient TMDL: dry and wet weather discharges will be monitored from agricultural, urban and open space sources to determine if best management practices are effective at reducing nutrient loading, Publicly Owned Treatment Works (POTW) monitoring is outlined in Plans submitted by permitees in Los Angeles and Ventura Counties.
Irrigated agriculture has been identified as the dominant source contributing to the issue of nutrients in the Lower Salinas River Watershed. Therefore, the monitoring plan for the LSRW should focus on quantifying agricultural nutrient sources. Monitoring may follow the requirements outlined in the Ag Waiver and then staff can evaluate the results to ensure that agricultural best practices are adequate to reduce nutrient levels.
Urban stormwater runoff is another important source of nutrients in the watershed. As the City of Salinas has already implemented a Storm Water Monitoring Program it would be advisable for water board staff to evaluate their results to ensure the Storm Water Management Program is effective at reducing nutrient effluent and has implemented Best Management Practices.
Linkage Analysis
In a TMDL document, the aim of the linkage analysis is to link pollutant loads to water quality. This link supports TMDLs (loading capacity per day) specified to meet the numeric target (overall load concentration).
No explicit linkage analysis was given in the 2012 draft report because the numeric target concentration is not finalized. Once a target has been established, the linkage analysis will be used to convert that target concentration to a recalculated daily load.
Margin of Safety
The margin of safety (MOS) for the Lower Salinas River Watershed is still being developed. A MOS is used to account for the uncertainty in the linkage between nutrient loads and nutrient pollutant concentrations in the receiving water body.
There are two methods to approach the margin of safety in a TMDL report. One incorporates uncertainties implicitly by using conservative estimates in the model. The other option for incorporating uncertainty (MOS) is to quantify a portion of the total TMDL, leaving the remainder as sources (allocations are important here). It is important to not only make conservative assumptions about the parameters, but the thresholds as well. Uncertainties that would be useful to take into consideration in regards to the LSRW include:
- finite data availability
- concentrations are discrete values that have been estimated based on a specific amount of parameters and do not necessarily account for the interactions of parameters
- the model may not be representative of the actual environmental conditions
- rain patterns vary from one year to the next so dilutions vary
- nutrients bioavailability to macrophytes
In order to develop a proper margin of safety it is useful to reference other TMDL reports(ELABORATE..).
Some reports employ conservative estimates within their water quality objectives, thus implicitly accounting for the margin of safety. An important factor to consider when using conservative estimates in lieu of quantitative margins is to explicitly address the individual assumptions that are being accounted for. An efficient way to make conservative assumptions on a in an efficient way is to assume low flow conditions. Some examples of reports that used conservative estimates include:
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. 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 important to note that this TMDL report has not yet been approved on the state or federal level.
The MOS for the Lower Salinas River Watershed is dependent on the assumptions put into the INN benthic biomass modeler. If all sources of variability have been accounted for in the model by incorporating conservative assumptions, then that may be stated as the margin of safety. However, if any significant uncertainties have not been incorporated in the model, an explicit margin of safety should be identified. The typical margin of safety that has been accepted in California is about 20%, but this can vary depending on land uses and other variables affecting nutrient loading into water bodies.
Load Allocations
TMDLs include the total concentration of nutrients allowed to be discharged into a water body by all possible sources. The allocations are typically comprised of Load Allocations (LAs) from nonpoint sources and Waste Load Allocations (WLAs) from point sources and also includes a Margin of Safety (MOS) to account for unexpected sources of a particular contaminant and Future Growth (FG), or as a formula:
TMDL = LAs + WLAs + MOS + FG
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.
In establishing TMDL allocations in the Lower Salinas River Watershed for nutrients, the Regional Water Quality Control Board could approach the allocations in a similar fashion as that taken in the Pajaro River Nitrate TMDL. By setting the load allocations as a concentration at or below the numeric target for all sources, future growth and changes in land use will not lead to an exceedance of the TMDL. This will also eliminate the need for setting critical conditions based on changes in flow rate, which would absolutely be required if allocations were set as loads given in mass.
Nitrate example
![](/wiki/images/thumb/6/6f/Nitrate_Map_2012TMDLDraftReport.png/350px-Nitrate_Map_2012TMDLDraftReport.png)
A recent (March 2012) preliminary draft project report by the California Regional Water Quality Control Board, (CRWQCB) Central Coast Region (CCRWQCB) on TMDLs for nutrients in the Lower Salinas River Watershed[1]Link to Waterboard TMDLs for Nutrients in the Lower Salinas Watershed [7]</ref>.
In this document, the work group identifies multiple beneficial uses (BUs) as impaired, including those for drinking water supply, livestock watering, and aquatic habitat BUs.
From the 2012 preliminary draft TMDL document[1]:
"Problem Statement: "Discharges of nitrogen compounds and orthophosphate are occurring at levels in surface waters which are impairing a wide spectrum of beneficial uses and, therefore, constitute a serious water quality problem. The municipal and domestic drinking water supply (MUN, GWR) beneficial uses and the range of aquatic habitat beneficial uses are currently impaired; potential or future beneficial uses of the agricultural irrigation water supply (AGR) for sensitive crops may be impaired..."
"A total of 34 waterbody/pollutant combinations are impaired due to exceedances of water quality objectives. The pollutants addressed in this TMDL are nitrate, un-ionized ammonia, and orthophosphate – orthophosphate is included as a pollutant due to biostimulatory impairments of surface waters. Reducing these pollutants is also anticipated to address several 303(d)-listed dissolved oxygen and chlorophyll a impairments in the TMDL project area."
Implementation
The 2012 draft TMDL report suggests that, "SWRCB, California Coastal Commission and other State agencies have identified management measures (MMs) to address agricultural sources of nutrient pollution that affect State waters."
To this end, they recommend nutrient management as outlined in the California Nonpoint Source Pollution Control Program [8].
On August 8, 1997, the Environmental Protection Agency (EPA) issued a memorandum [8] , “New Policies for Establishing and Implementing Total Maximum Daily Loads (TMDLs),” which directs EPA regions to work in partnership with states to achieve nonpoint source load allocations established for 303(d)-listed waters impaired solely or primarily by nonpoint sources.
To this end, the memorandum asks that regions assist states in developing implementation plans that include reasonable assurances that the nonpoint source load allocations established in TMDLs for waters impaired solely or primarily by nonpoint sources will in fact be achieved; a public participation process; and recognition of other relevant watershed management processes. Although implementation plans are not approved by EPA, they help establish the basis for EPA’s approval of TMDLs.
The purpose of an Implementation Plan is to describe the steps necessary to reduce pollutant loads to achieve these TMDLs. Implementation Plans identify the following: 1) actions expected to reduce pollutant loading; 2) parties responsible for taking these actions; 3) regulatory mechanisms by which the Central Coast Water Board will assure these actions are taken; 4) reporting and evaluation requirements that will indicate progress toward completing the actions; 5) a timeline for completion of implementation actions. Implementation Plans also address economic considerations to achieve compliance. 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 stormwater 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.
Irrigated agriculture has been identified as the dominant source contributing to the issue of nutrients in the Lower Salinas Watershed. Regulations can follow those set forth in the Ag Waiver. It is also advisable for Water Board staff to incorporate educational outreach programs to encourage the adoption of Best Management Practices on all croplands.
Public Participation
![](/wiki/images/thumb/2/2d/TMDLGraphic.png/275px-TMDLGraphic.png)
Public participation is a requirement [8] of the TMDL process and is vital to a TMDL’s success. The August 23, 1999, proposed regulation states that the public must be allowed at least 30 days to review and comment on a TMDL prior to its submission to the EPA for review and approval. In addition, with a TMDL submittal, the EPA must be provided with a summary of all public comments received regarding the TMDL and staff response to those comments, indicating how comments were considered in the final decision.
Typically a TMDL report may go through one or more cycles where staff receive public comments and revise the report to reflect those comments appropriately. The figure (right) is an example of the iterative development process (Factsheet).
Due to the large number of stakeholders that will be affected by the implementation of Lower Salinas River Watershed Nutrient TMDL, it is advisable to schedule at least three or more public hearings and collaborative stakeholder meetings during different stages of the process.
The development of this TMDL will affect many stakeholders regulated by the California Environmental Quality Act (CEQA), therefore staff should be prepared to respond to any related questions or comments during public meetings.
During the development of the Fecal Coliform TMDL report for the Lower Salinas River Watershed (2010 Report), Water Board staff conducted stakeholder outreach efforts throughout the process. Water Board staff made several presentations to engage stakeholders and results were presented in newspapers and television media. In addition, a CEQA stakeholder scoping meeting was held in June of 2007 and another stakeholder meeting was held in August of 2009. A formal Central Coast Water Board public hearing was also held and public comments were solicited prior to the hearing.
Stakeholders included:
- The City of Salinas
- CCRWQCB [9]
- California Coastkeeper Alliance [10]
- Central Coast Agricultural Task Force
- Central Coast Water Quality Preservation, Inc. (CCWQPI)
- Commercial Ranches
- Commercial Farms
- Grower-Shipper Association of Central California [11]
- Monterey Bay National Marine Sanctuary
- Monterey County Agricultural Commissioner’s Office
- Monterey County Farm Bureau
- Monterey County Cattlemen’s Association
- Monterey County Department of Environmental Health
- Monterey County Water Resources Agency
- NMFS [12]
- Resource Conservation District of Monterey County
- State of California Department of Health Services
- United Fresh Fruit and Vegetable Association
- United States Department of Agriculture
- United States Food and Drug Administration
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Link to Central Coast Water Quality Control Board's draft TMDLs for Nutrients in the Lower Salinas Watershed [1]
- ↑ SWRCB list of US EPA approved and effective TMDLs for California [2]
- ↑ Keller AA, Zheng Y, Robinson TH. 2004. Determining critical water quality conditions for inorganic nitrogen in dry, semi-urbanized watersheds. JAWRA 40(3): 721-735. Available from: http://onlinelibrary.wiley.com/doi/10.1111/j.1752-1688.2004.tb04455.x/abstract
- ↑ [3]. Overview of TMDL development process from US EPA]
- ↑ Anderson T, Watson F, Newman W, Hager J, Kozlowski D, Casagrande J, Larson J. 2003. Nutrients in surface waters of the southern Monterey Bay watersheds. Central Coast Watershed Studies
- ↑ UC Davis contract study report on the Tulare Valley and Lower Salinas Watershed addressing nitrates in the California's drinking water [4]
- ↑ [5].
- ↑ 8.0 8.1 [6]
Links
- Beneficial uses
- TMDLs in the Monterey Bay Region of California
- TMDL for Chlorpyrifos and Diazinon in Lower Salinas River Watershed, Monterey County, California
- Central Coast Ambient Monitoring Program
- Central Coast Watershed Studies Team
- Central Coast Regional Water Quality Control Board 303(d) Investigations and TMDL Projects
- July 2000 EPA Nutrient Criteria Technical Guidance Manual for Rivers and Streams
- Tetratech Final California Nutrient Numeric Endpoints (NNE) Report 2006
Disclaimer
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