Source area management practices as remediation tool to address groundwater nitrate pollution in drinking supply wells

Journal of Contaminant Hydrology (Elsevier) | July 19th, 2019

Nitrate in drinking water may cause serious health problems for consumers. Agricultural activities are known to be the main source of groundwater nitrate contaminating ru

Nitrate in drinking water may cause serious health problems for consumers. Agricultural activities are known to be the main source of groundwater nitrate contaminating rural domestic and urban public water supply wells in farming regions. Management practices have been proposed to reduce the amount of nitrate in groundwater, including improved nutrient management practices and “pump and fertilize” with nitrate-affected irrigation wells. Here, we evaluate the feasibility and long-term impacts of agricultural managed aquifer recharge (Ag-MAR) in the source area of public water supply wells. A numerical model of nitrate fate and transport was developed for the Modesto basin, part of California's Central Valley aquifer system. The basin is representative of semi-arid agricultural regions around the world with a diversity of crop types, overlying an unconsolidated sedimentary aquifer system. A local public supply well in an economically disadvantaged community surrounded by farmland was the focus of this study. Model scenarios implemented include business as usual, alternative low-impact crops, and Ag-MAR in the source area of the public supply well. Alternative nutrient management and recharge practices act as remediation tools in the area between farmland and the public supply well. Improved agricultural source area management practices are shown to be an effective tool to maintain or even enhance groundwater quality in the targeted supply well while remediating ambient groundwater.

Source, movement and age of groundwater in the upper part of the Mojave River Basin, California, USA

Proceedings of the 1994 International Symposium on Application of Tracers in Arid Zone Hydrology | August 22nd, 1996

Water samples from wells were collected and analysed for oxygen-18, deuterium, tritium, carbon-14, and carbon-13 to determine the source, movement and age of groundwate

Water samples from wells were collected and analysed for oxygen-18, deuterium, tritium, carbon-14, and carbon-13 to determine the source, movement and age of groundwater in the upper part of the Mojave River basin. Water in the alluvial aquifer has a median deuterium composition of — 66% and contains tritium, and was recently recharged by water from the Mojave River. Water in the regional aquifer near the Mojave River, near Summit Valley, and underlying several small washes has deuterium compositions heavier than — 60 %. Although some water in the regional aquifer near the Mojave River contains tritium, most of this water does not contain tritium. Carbon-14 data indicate that this water was recharged less than 2400 years ago. Water in the remainder of the regional aquifer has a median deuterium composition of — 84 %, which is as much as 20 % lighter than the volume-weighted deuterium composition of present-day precipitation. These data show that this water was recharged under climatic conditions different from average conditions today. Carbon-14 data indicate that some water in the regional aquifer was recharged more than 20,000 years ago.

Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

Hydrogeology Journal (Springer) | July 3rd, 2015

State of the Salinas River Groundwater Basin

Monterey County Water Resources Agency (MCWRA) | January 16th, 2015

From 6.3 Steps Appropriate to Address Water Supply under Continued Drought Conditions:  Based on the continued large storage declines in the East Side and Pressure Su

From 6.3 Steps Appropriate to Address Water Supply under Continued Drought Conditions:  Based on the continued large storage declines in the East Side and Pressure Subareas (and resulting groundwater head declines and seawater intrusion), the current distribution of groundwater extractions is not sustainable. Seawater intrusion can account for up to 18,000 afy of the total storage loss of up to 24,000 afy. Sustainable use of groundwater can only be achieved by aggressive and cooperative water resources management. The consequences of no-action under continued drought conditions will be the imminent advancement of seawater intrusion within the next few years and the continued decline of groundwater head. Both of these conditions would necessitate the drilling of deeper groundwater wells, which may not be feasible in some areas because of lower groundwater yield and water quality in the Pressure Deep Aquifer. A more sustainable long-term management practice would encourage the Basin-wide redistribution and reduction of groundwater pumping, which would require cooperative and aggressive resource management. The unsustainability of the current distribution of groundwater extractions has long been recognized by various investigators, and a Basin-wide redistribution and reduction in pumping has been recommended previously (e.g. DWR, 1946). 6.3.1 Technical Option 1:  The large storage declines that have occurred in the Basin in the past, especially in the East Side Subarea, have created a significant landward groundwater head gradient that must be reversed before seawater intrusion can be halted. Reduction of pumping in the Pressure and East Side Subareas could help mitigate some of the anticipated effects of extended drought on groundwater storage and water quality in the study area. Shifting of pumping to areas further away from the coast would also be helpful, as long as it is shifted south of the current head trough (Figure ES3) that exists in the East Side Subarea. One of the main reasons that substantial steps must be taken to curtail seawater intrusion is that the large storage declines that have occurred in the Basin in the past (especially in the East Side Subarea) have created a significant landward groundwater head gradient that must be reversed before seawater intrusion can be halted. 6.3.2 Technical Option 2: The shifting of some pumping from the P-180 and P-400 Aquifers to the Pressure Deep Aquifer would reduce the storage deficit in the shallower aquifers; however, this would necessarily lead to head declines in the Pressure Deep Aquifer. Unlike the P-180 and P-400 Aquifers, it is not known whether or not the Pressure Deep Aquifer is hydraulically connected to the ocean in Monterey Bay, so it is not known whether this pumping shift would lead to the onset of regional seawater intrusion. Also unknown is the likelihood of localized interaquifer seawater mixing between the Pressure 400- Foot Aquifer and the Pressure Deep Aquifer. Hence, this Management Option requires more investigation to determine its feasibility. 6.3.3 Evaluation of Potential Solutions: The numerical modeling analysis to be performed as a second part of this Basin Investigation will consider the effects of various management decisions on the water supply and water quality in the study area. The primary questions to be assessed for each scenario are: 1) what will be the rate of groundwater head decline; and, 2) what will be the rate of increase in acreage with impaired water quality due to the advancement of the seawater intrusion front. We can then assess the economic effects of 1) and 2) due to water supply wells becoming inoperable (i.e. dry), and the further loss of aquifer storage capacity due to the advancement of seawater intrusion. The numerical model should be used to predict groundwater head declines under different management scenarios, including implementing targeted pumping rates and optimizing the distribution of pumping. Future declines in groundwater head must be evaluated by simulated groundwater conditions so that “trigger (groundwater) head levels” can be used as a measure of safe yield and an early alert system as part of Basin Management Objectives. That analysis will extend the discussions and conclusions presented in this report.

Stockton East Water District - Groundwater Recharge Basin, Southeast Recharge Basin

U.S. Bureau of Reclamation (USBR) | February 15th, 2018

Quality regulations (40 CFR 1500 - 1508), and Department of the Interior Regulations (43 CFR Part 46), the Bureau of Reclamation (Reclamation) prepared this env

Quality regulations (40 CFR 1500 - 1508), and Department of the Interior Regulations (43 CFR Part 46), the Bureau of Reclamation (Reclamation) prepared this environmental assessment to evaluate and disclose potential environmental impacts associated with providing funds to the Stockton East Water District (SEWD) in San Joaquin County, California to construct a new 73-acre groundwater recharge basin . Reclamation would provide $300,000 through the Drought Response Program to SEWD for the development of a groundwater recharge basin. The Drought Response Program is a program designed to help water users develop drought contingency plans and build long-term drought resilience.

Stony Creek Fan Conjunctive Water Management Plan Feasibility Investigation

Glenn-Colusa Irrigation District | February 15th, 2004

Stormwater Capture: Enhancing Recharge and Direct Use Through Data Collection

Southern California Water Coalition | April 26th, 2018

The purpose of this 2018 white paper update is to gain a better understanding of actual stormwater runoff capture volumes, costs, benefits, and project performa

The purpose of this 2018 white paper update is to gain a better understanding of actual stormwater runoff capture volumes, costs, benefits, and project performance across the region to inform future discussions. This white paper augments prior efforts and uses the most recent and best available stormwater project data. Previously in January 2012, the SCWC published its first white paper on stormwater titled Stormwater Capture: Opportunities to Increase Water Supplies in Southern California (SCWC 2012). The purpose of the 2012 white paper was to examine existing statewide policies, goals, and regional plans related to integrated stormwater management; trends, structure, and requirements of MS4 permits as they pertain to both opportunities and constraints to maximizing stormwater capture for water supply purposes; and the advantages and disadvantages of two strategies of stormwater management: onsite low impact development and regional stormwater capture and infiltration. Lastly, the 2012 white paper largely focused on conceptual stormwater projects and technical strategies for increasing stormwater capture. Since the 2012 white paper, many of the proposed projects were constructed and in operation. Other plans such as Metropolitan’s 2015 Integrated Resources Plan (MWD 2016), the City of Los Angeles’s Stormwater Capture Master Plan (LADWP 2015), and Los Angeles County Flood Control District’s LA Basin Study (LACFCD 2016) also estimated stormwater capture and costs. The SCWC saw an opportunity to evaluate the costs and benefits of these constructed stormwater capture projects and pursued a white paper update.

Stormwater Funding Options Providing Sustainable Water Quality Funding in Los Angeles County

California Contract Cities Association (CCCA) | May 21st, 2014

The Los Angeles region faces critical, very costly, and seriously underfunded stormwater and urban runoff water quality challenges. The Los Angeles County Flood Control D

The Los Angeles region faces critical, very costly, and seriously underfunded stormwater and urban runoff water quality challenges. The Los Angeles County Flood Control District (LACFCD) led a multi-year effort to develop a sustainable revenue source for municipalities to manage stormwater programs and implement water quality improvement projects. This effort included special legislation and development of a proposed parcel fee, the “Clean Water, Clean Beaches Measure,” to fund clean water programs. At extended protest hearings on a proposed parcel fee in January and March of 2013, the Board of Supervisors heard concerns about the fee and the fee program from public schools, the business community, other stakeholders and the public. The Board moved to close the public hearing and determined to “not proceed at this time with the Clean Water, Clean Beaches measure as proposed.” In June 2013, the Board adopted a motion requesting collaborative participation with the County Sanitation Districts of Los Angeles County (LACSD) and other wastewater management agencies to evaluate methods, assess the a potential model governance structure, and to help identify and secure other sources of funding. In response to the Board’s actions, the City Managers Committees of the California Contract Cities Association (CCCA) and the League of California Cities, Los Angeles County Division (League) convened a City Managers meeting with representatives from public schools, environmental organizations, and the business community on June 27, 2013 to hear stakeholders’ concerns and suggestions directly. The City Managers attending the meeting authorized a Work Group to review stormwater funding options after the County’s proposed Clean Water, Clean Beaches funding initiative failed to move forward. The City Managers Work Group actively sought the input of key stakeholders from the environmental, public education, and business communities, and prepared this report to assist the Board, local decision makers, stakeholders, and the public in reaching a common understanding of the issues at hand and the potential solutions. The Managers found that to fully understand the issues, improved communication and education is necessary. This report describes the stormwater regulatory requirements speci c to the greater Los Angeles area, the complexities of funding stormwater programs, and the LACFCD’s funding initiative. It examines the regulatory framework for stormwater management, including the requirements of the National Pollution Discharge Elimination System (NPDES) MS4 permit (stormwater permit) and the total maximum daily load (TMDL) programs. The report also summarizes the impacts of the federal TMDL Consent Decree for the Los Angeles Region signed in 1999, which has indirectly regulated the LACFCD, 85 cities, and the unincorporated County since that time. Further, it reviews estimated stormwater program compliance costs, the “pros and cons” of various funding options, and evolving opportunities. The report concludes with a series of recommendations agreed upon by the City Managers. Suggestions from an Elected Officials Committee and individual City Attorneys are also included in this report. The Work Group found that funding urban runoff programs is so complex and dynamic, and the solutions so costly, that the County and the Cities cannot follow a single funding strategy at this time. One option, for example, is to examine institutional roles to determine whether other agencies, such as the County Sanitation Districts, either provide a useful governance model or could play a new or different role in managing stormwater in the future. During the report development process, the Sixth Appellate Court clarified the application of Proposition 218 regarding the imposition of fees for the capture and use of stormwater for groundwater recharge (Griffith v. Pajaro Water Management Agency). This ruling could have major implications on funding options. These are only two examples of the changing nature and complexities in charting a path forward. The City Managers Work Group recommends a “multi-pronged” approach to address urban runoff funding issues, since our communities may encounter several dead-ends. A number of the recommendations require active management and a higher degree of organization by local government. The recommended actions are voluntary. The report is not advocating that any city, group of cities, or the County adopt stormwater fees. The managers are committed to local control; if a regional fee moves forward, each community should make its own decision whether or not to participate in the regional effort. However, there are steps that local governments can take that will assist in funding the new stormwater mandates. For example, cities should organize and be active in the water bond discussions. This report suggests a voluntary framework through Contract Cities and the League to organize those communities that desire to engage in implementing the recommendations found in this report. It should be noted that the recommendations involving California Contract Cities, the Los Angeles County Division of the League of California Cities, and the State League of Cities have not been of cially endorsed by these organizations at this stage of the process. The City Managers Work Group and the Elected Of cials Committee held detailed discussions with staff from both organizations in order to re ect their input and concerns. Recommendations involving these organizations, such as changes in State legislation, would need to be reviewed and approved by each organization.

Subsurface water flux in California's Central Valley and its source watershed from space geodesy

American Geophysical Union (AGU) | September 29th, 2022

We combine measurements from Global Positioning System positioning and Gravity Recovery and Climate Experiment gravity to infer change in water components in Central Vall

We combine measurements from Global Positioning System positioning and Gravity Recovery and Climate Experiment gravity to infer change in water components in Central Valley and its source watershed, the Sacramento-San Joaquin-Tulare River basin better than possible with either technique separately. We find that the Central Valley has lost groundwater from 2006 to 2021 at 2.2 ± 0.7 km 3/ yr (95% confidence limits follow the “±” sign), with 2/3 of the groundwater loss occurring in the southern part of the Valley. We estimate the seasonal recharge and loss of subsurface water in the Central Valley. Comparison to a model accounting for precipitation, evapotranspiration, and river water entering and leaving the Central Valley suggests that deep groundwater may be flowing from the Sierra Nevada mountains into the Central Valley.

Sustainable Water Management Strategy for Specialty Crop Expansion in the Sacramento Valley

Sacramento Area Council of Governments (SACOG) | June 26th, 2018

The Sacramento Area Council of Governments (SACOG) is an association of local governments in the six-county Sacramento Region of El Dorado, Placer, Sacramento, Sutter, Yo

The Sacramento Area Council of Governments (SACOG) is an association of local governments in the six-county Sacramento Region of El Dorado, Placer, Sacramento, Sutter, Yolo, and Yuba counties (excluding the Tahoe Basin in Placer and El Dorado counties) and the 22 cities therein. SACOG provides planning and funding for the region and serves as a forum for the study and resolution of regional issues. SACOG prepares the region’s long range plan which considers both transportation and land use. Through the lens of rural planning, SACOG has actively engaged in a Rural-Urban Connections Strategy (RUCS) Program that has studied ways to enhance rural economies and natural assets. The RUCS Program includes a scenario analysis modeling tool that links a parcel-level crop map with environmental and economic factors, including a comprehensive profile of per acre operational cost and return metrics for each crop. The study described in this report looks at how new agricultural crops and markets coupled with improved irrigation techniques will support new specialty crop acreage in the SACOG area. While new and improved irrigation techniques can result in better crop yields and decreased water demands, increases in irrigation efficiency also result in reduced groundwater recharge from irrigation return flows. SACOG received grant funding from the California Department of Food and Agriculture (CDFA) to evaluate the feasibility of recharging groundwater on agricultural lands within the SACOG portion of the Sacramento Valley to benefit specialty crop production. The primary goal of the project is to bring together a broad range of different factors impacting groundwater recharge and infiltration and to identify areas across the region that are most suited for strategic flooding of specialty crop fields; in other words, areas that will most efficiently and effectively facilitate recharge, while minimizing cost to the specialty crop producer. Ultimately, this feasibility information will be incorporated into SACOG’s RUCS model to evaluate the potential benefits of recharging groundwater on agricultural land for the benefit of specialty crops.