Some of the data are further broken down by groundwater sub-basin or county. Is the resultant brine from reverse osmosis considered hazardous waste, and if so, who will be responsible for discarding it, and how will it be handled? The appropriate disposal of waste brine or concentrate from nitrate treatment will depend on several factors including co-contaminants, the strength or concentration of the waste stream, and the volume of the waste stream. The presence of contaminants other than nitrate e. Methods for disposal of waste brine or concentrate reported in the survey of nitrate treatment systems in CA include discharge to a septic tank and leach fields, to a wastewater treatment plant via a sewer connection, to irrigation ponds, to a brine line, and to a wastewater treatment plant via trucking.
Based on the water quality characteristics of the waste stream, waste disposal options for a nitrate treatment system in a public water system will be considered in the planning and design phases to select the most appropriate fate of the waste stream under state and local regulations. On a residential scale, the waste stream from a Point-of-Entry POE or Point-of-Use POU system would typically be discharged through a sewer connection or, depending on brine volume and water quality characteristics, to a septic system.
The emergency regulations regarding the use of POU or POE treatment units for small public water systems in California indicate the need to address waste disposal as part of the development of an Operations and Maintenance Program for review by the California Department of Public Health.
Did you conduct an economic analysis of the cumulative impact of adding regulations on top of existing regulations? The report did not specifically analyze the cost of regulations or the cost of multiple regulations. The report outlines current regulatory programs and potential options. It clearly identifies and compares, in general terms, the cost of such regulations for various options. The report also estimates the cost of reducing nitrate loading from various sources, including agriculture, that arise from investments into additional infrastructure, education, labor, and monitoring.
The report does discuss as a dilemma for the state that current policy has separate state agencies for nitrate, pesticide, and air pollution emissions from the same land use. Can this be streamlined to make it more effective? The cost of remediation is excessively high and its technical feasibility at this scale questionable. Large scale, basin-wide remediation via pump-and-treat is not a viable option.
In regard to problem identification, do cost estimates consider application stationing and does groundwater recognize borders? The study does not develop place-specific solutions. Instead, the study provides information on the use of specific management practices agricultural nitrate loading or specific drinking water supply options and outlines under what circumstances, which options are more promising.
These options take into consideration that groundwater is controlled by natural boundaries and the makeup of the aquifer systems in the Salinas Valley and Tulare Lake Basin. We did not evaluate the effect of taxing synthetic fertilizer only on potentially more widespread distribution of manure. In general, the effect on groundwater from additional use of manure in lieu of synthetic fertilizer depends on the farmer's management practices.
It may or may not lead to changes in groundwater quality impacts. Only if the use of manure results in higher applications of nitrogen, when compared to applying only synthetic nitrogen fertilizer, groundwater nitrate leaching will increase unless the harvested nitrogen increases proportionally. For a farmer, switching from synthetic fertilizer to manure as fertilizer is a significant shift in nutrient management practices. The UC Davis study states that regulations alone are not adequate to resolve the nitrate problem.
Will these programs be allowed adequate time to prove their effectiveness or ineffectiveness?
Nitrates in groundwater
These programs are highlighted in the report and are among several programs already in place. The analysis and options outlined in our report are not considered to be new alternatives to these existing programs, but may further inform these ongoing programs as they develop. Will the suggested fees be broken down proportionately as to who will pay them, i. We outline several options that the state or even a county may pursue. Some focus on polluters, some are general fees.
Should the State be doing more or less on the issue of nitrate in groundwater than they are currently doing? The report outlines a number of promising actions for the State to more effectively and efficiently address nitrate in drinking water. Without any additional State efforts, the problem cannot be addressed. How did you come up with your nitrogen loading numbers? Nitrate loading was evaluated by various methods described in Technical Report Did you acknowledge the beneficial reuse and existing regulatory environment of land application of biosolids?
This issue is discussed in Technical Report 2 Chapter 6. All sources of nitrogen were tallied in the overall mass balance approach, and biosolids were included in this total. Farmers always cut back on synthetic nitrogen on manured ground. Why do you assume that farmers applying organic N manure continue to add synthetic fertilizer? In surveys conducted prior to the Dairy General Order, dairy farmers in the Central Valley reported using significant amounts of synthetic fertilizer on their crops.
Estimating the release of available N from organic sources is complicated by many factors making it difficult to replace synthetic fertilizer N with manure N at a 1: This difficulty in determining the nutrient value of manure contributes to total N applications often being higher than under a strictly synthetic fertilizer regime, while also providing significant benefits to soil quality. Growers who use manure or other organic amendments primarily as a soil amendment may reduce fertilizer applications, but not at a 1: Clearly, further data is needed to make a more specific assessment of current practices.
Have you conducted a separate analysis for manure-applied vs. Yes, Appendix Table 7 in Technical Report 2 lists, for each crop, the estimated nitrogen typically applied and the estimated amount of nitrogen typically harvested. Chapter 3 of Technical Report 2 explains how these numbers were obtained. In general, these numbers reflect typically applied synthetic fertilizer.
Chapter 4 of Technical Report 2 explains application of manure to forage crops and our assumptions about the amount of manure N that replaces synthetic fertilizer N on dairies. How many farms, dairies, etc. Five expert panels were convened to assemble, discuss, and evaluate a list of recommended practices that would support significant reductions of nitrate leaching to groundwater. Each panel included 2 Cooperative Extension advisors, growers, and crop management professionals or other industry personnel, such as certified crop advisors.
How fast or slow does nitrate move through the soil profile, from time of application to the time it reaches the groundwater? The movement of nitrate through the soil profile depends on the time of application, the subsequent timing and amount of rainfall and irrigation, and the rate of plant water and nitrate uptake.
If nitrogen is applied in organic form or as ammonia, the rate of nitrate movement will also depend on how quickly organic nitrogen is mineralized to ammonia, and how quickly the ammonia is then converted to nitrate. Organic nitrogen and ammonia nitrogen are "sticky" and most of it remains in the root zone near the soil surface.
But nitrate is very mobile and readily displacable by water movement.
Once nitrate leaves the root zone, the travel time to groundwater depends on the depth to groundwater and the amount of water percolating out of the root zone from irrigation and rainfall. Technical Report 4 Chapter 6 provides a detailed analysis of the potential travel time of nitrate between the root zone and groundwater. Was support for organic agriculture considered as a source reduction option? If so, please explain. We did not specifically address organic agriculture in this report.
Instead, Technical Report 3 considers specific recommended practices, some of which may already be practiced by farmers, that would at least partially address nitrate leaching. Many growers are harvesting higher yields today than they did 10 or 20 years ago, while keeping their fertilizer use approximately the same or even reducing fertilizer use in some cases. Why are there high levels of groundwater nitrate along the foothill regions? The Central Valley aquifer system tends to be more sandy along the eastern margin near the foothills.
There, it is also not very thick; hence, many wells are drilled to relatively shallow depths. The region is therefore very vulnerable to nitrate contamination of drinking water wells. Is it possible that the estimated increase of nitrate in groundwater may have been skewed by an increase in drilling wells in contaminated areas? The long-term trends seen in the groundwater nitrate data partially reflect not the drilling of new wells, but the fact that more wells are being tested in recent years, at least in some areas. In other areas, testing programs in the s, s, and s on certain wells have since stopped.
The trend analysis accounted for some of these changes, by breaking out data from separate programs, and by considering trends at individual wells in addition to trends in averages across multiple wells see Technical Report 4 Why do you expect a higher rate of future degradation of groundwater?
Groundwater nitrate loading has not diminished and in many areas has increased. The effect of that loading will continue to be felt in groundwater wells for years and decades. And, how do you define natural background nitrate? We did not establish specific background nitrate levels. Did you conduct any testing of aged groundwater, or was aged groundwater used in any of the comparisons?
The USGS has done some analysis of the groundwater age distribution with depth and how it relates to nitrate levels. Are there other areas of California that have high nitrogen levels, and did you project a cost estimate for the entire state? There are other areas in California with high nitrate levels in groundwater. We did not project cost estimates to these regions. New York, Springer-Verlag; — Gateway to the Earth. Laboratories Fluid processes Geochemistry Geotechnics and geophysics Mineralogy and petrology.
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