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.

Temporal and Spatial Patterns of Groundwater Recharge Across a Small Watershed in the California Sierra Nevada Mountains

Frontiers in Water (Frontiers) | May 17th, 2022

Mountain-block groundwater recharge is a crucial freshwater source in arid to semiarid watersheds worldwide; yet its quantification is difficult due to (1) hydrogeologica

Mountain-block groundwater recharge is a crucial freshwater source in arid to semiarid watersheds worldwide; yet its quantification is difficult due to (1) hydrogeological heterogeneities especially in bedrock-dominated regimes, (2) drastic altitudinal ranges in climate, land use and land cover, and (3) mixing with deep groundwater derived from adjacent basins (i.e., interbasin groundwater flow). In this study, we test the utility of soil water-balance (SWB) modeling to quantify mountain-block groundwater recharge in the South Fork Tule River watershed in the California Sierra Nevada Mountains. This 1,018 km2 watershed is instrumented with 3 USGS stream gages that allow for the development of a refined recharge (i.e., baseflow) calibration dataset via multi-objective optimization-based hydrograph separation. The SWB model was used to compute groundwater recharge and other water balance components at a daily time step using a 30-m grid cell size for a 40-year (1980–2019) study period. Mean annual recharge and runoff were estimated at 3.7 in/yr (3.0 m3/s) and 1.4 in/yr (1.2 m3/s), respectively, with modified Nash Sutcliffe Efficiency indices of 0.61 between baseflow and SWB-derived recharge, and 0.90 between hydrograph separation- and SWB-derived runoff. There is a strong correlation between annual recharge and rainfall (Pearson R = 0.95, p < 0.001) which attests to short residence times in the unsaturated zone and the immediate impact of droughts in 1990, 1999, and 2013. However, results of a modified Mann-Kendall trend analysis indicate no directional trends in recharge or runoff throughout the study period. Parameter sensitivity analyses reveal a persistent overprediction of recharge over baseflow that is particularly pronounced in the upper reaches of the watershed. This is likely related to the SWB model only considering soil characteristics at the surface and not simulating the fate of potential recharge below the root zone where it may be impeded from reaching the aquifer by shallow, impermeable bedrock. This limitation should be considered carefully for future water supply projections in this and comparable bedrock-dominated settings.

The Basin Characterization Model—A Regional Water Balance Software Package

U.S. Geological Survey (USGS) | March 22nd, 2021

This report documents the computer software package, Basin Characterization Model, version 8 (BCMv8)—a monthly, gridded, regional water-balance model—and provides det

This report documents the computer software package, Basin Characterization Model, version 8 (BCMv8)—a monthly, gridded, regional water-balance model—and provides detailed operational instructions and example applications. After several years of many applications and uses of a previous version, CA-BCM, published in 2014, the BCMv8 was refined to improve the accuracy of the water-balance components, particularly the recharge estimate, which is the most difficult to accurately assess. The improvement of the various water-balance components targeted the actual evapotranspiration component, which, in turn, reduced the uncertainty of the recharge estimate. The improvement of this component was enabled by the availability of a national, gridded actual-evapotranspiration product from the U.S. Geological Survey that was unique in its scope to combine remotely sensed spatial variability and ground-based long-term water-balance constraints. This dataset provided the ability to assess monthly actual evapotranspiration for 62 vegetation types and to perform regional calibration in watersheds throughout California with the objective of closing the water balance using improved estimates for each component. The refinements, including vegetation-specific evapotranspiration, enabled the development of applications that could explore various aspects of landscape disturbance, such as wildfire, forest management, or urbanization. The improvements to BCMv8 also provided the ability to assess long-term sustainability of water resources under a variety of management applications or future climate projections.

The Big Water Supply Shift: Groundwater Key to Water Security in California's Changing Climate

Union of Concerned Scientists | November 1st, 2015

For more than a century, California has relied on its snowmelt-fed reservoirs, rivers, and streams for the majority of its water, but drought and climate chang

For more than a century, California has relied on its snowmelt-fed reservoirs, rivers, and streams for the majority of its water, but drought and climate change are depleting those traditional supplies. Snow is already melting as many as 30 days earlier than in the mid-twentieth century, meaning less water is available during the hotter months when water demand is highest. California is increasingly turning to groundwater to meet its water needs. Today, groundwater supplies up to 50 percent of California’s water, but California’s prolonged drought has led to the over-pumping of groundwater, overdrafting the Central Valley’s aquifers. Sustainable groundwater management will allow the state to adapt to climate change while increasing water reliability in the future.

The effects of artificial recharge on groundwater levels and water quality in the west hydrogeologic unit of the Warren Subbasin, San Bernardino County, California

U.S. Geological Survey (USGS) | November 4th, 2013

The importance of imperviousness

Watershed Protection Techniques, Center for Watershed Protection | December 1st, 1994

The emerging field of urban watershed protection often lacks a unifying theme to guide the efforts of its many participants—planners, engineers, landscape architects

The emerging field of urban watershed protection often lacks a unifying theme to guide the efforts of its many participants—planners, engineers, landscape architects, scientists, and local officials. The lack of a common theme has often made it difficult to achieve a consistent result at either the individual development site or cumulatively, at the watershed scale. In this article a unifying theme is proposed based on a physically defined unit: imperviousness. Imperviousness here is defined as the sum of roads, parking lots, sidewalks, rooftops, and other impermeable surfaces of the urban landscape. This variable can be easily measured at all scales of development, as the percentage of area that is not “green.” Imperviousness is a very useful indicator with which to measure the impacts of land development on aquatic systems. Reviewed here is the scientific evidence that relates imperviousness to specific changes in the hydrology, habitat structure, water quality and biodiversity of aquatic systems. This research, conducted in many geographic areas, concentrating on many different variables, and employing widely different methods, has yielded a surprisingly similar conclusion: stream degradation occurs at relatively low levels of imperviousness (~10%). Most importantly, imperviousness is one of the few variables that can be explicitly quantified, managed and controlled at each stage of land development. The remainder of this article details the relationship between imperviousness and stream quality.