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Independent Review Panel (IRP) Report for the 2017 Long-term Operations Biological Opinions (LOBO) Biennial Science Review (January 24, 2018)
Independent Review Panel (IRP) Report for the 2017 Long-term Operations Biological Opinions (LOBO) Biennial Science Review (January 24, 2018)Delta Stewardship Council (DSC) | January 31, 2018...Summary
Mojave Region Functionally Equivalent Storm Water Resources Plan
Mojave Region Functionally Equivalent Storm Water Resources PlanMojave Water Agency (MWA) | October 4, 2017...Summary
The State of California now recognizes the importance of incorporating storm water as a potential resource in a region’s water portfolio. Historically, storm water...
The State of California now recognizes the importance of incorporating storm water as a potential resource in a region’s water portfolio. Historically, storm water was thought of as a public risk (e.g., flooding) and a source of water quality impairment. Traditional approaches for storm water focused on diverting storm water into the storm drain system which ultimately and efficiently moved said water away from populated areas; the State is now supporting watershed-based approaches where storm water and dry weather runoff can yield benefits beyond flood control, such as water supply, water quality improvement, and habitat enhancement. To incentivize use of storm water, the State of California has linked storm water resources planning to state funding. Storm water and dry weather runoff capture projects seeking funding from any California bond act approved by voters after January 1, 2014 must be included in a Storm Water Resources Plan, which meets California Water Code.
Regional water planning has a long history in the Mojave region. In 2005, agencies in the Mojave service area, that share a common concern for the area’s water resources, met and agreed to develop an Integrated Regional Water Management Plan (IRWMP). The Region’s first IRWMP identified, defined, and established strategies to capitalize on all water management opportunities that were present at that time or would become possible in the Mojave Region in the future. Since that time the IRWMP has acted as a forum for regular collaboration. The IRWMP is a living document and the regional objectives as well as strategies to improvement water management are regularly updated. The IRWMP was last updated in 2014.
This Mojave Region Storm Water Resource Plan (SWRP) is an extension of the IRWMP process and is meant to bring an integrated and watershed-based approach to managing and creating benefits from storm water. This SWRP is regional and multi-agency. This SWRP includes all components required by the Water Code and will be submitted to the IRWM group. This SWRP will help entities in the Mojave Region identify, prioritize, and implement storm water projects.
Final Mojave Region Integrated Regional Water Management Plan
Final Mojave Region Integrated Regional Water Management PlanMojave Water Agency (MWA) | June 1, 2014...Summary
Water Supply and Habitat Resiliency for a Future Los Angeles River: Site-Specific Natural Enhancement Opportunities Informed by River Flow and Watershed-Wide Action
Water Supply and Habitat Resiliency for a Future Los Angeles River: Site-Specific Natural Enhancement Opportunities Informed by River Flow and Watershed-Wide ActionThe Nature Conservancy | December 15, 2016...Summary
The mission of The Nature Conservancy is to conserve the lands and waters on which all life depends. As the Conservancy engages with...
The mission of The Nature Conservancy is to conserve the lands and waters on which all life depends. As the Conservancy engages with the Los Angeles region, they are investigating what it means to carry out this mission in the highly urbanized Los Angeles River ecosystem. As a starting point, it is known that the basic ecological principles of science apply to all environmental systems, regardless of their location. Therefore, the Conservancy is testing these principles by applying them in the Elysian Valley of the Los Angeles River and identifying habitat enhancement requirements, opportunities, and constraints.
As a basic principle of ecological systems, a watershed’s hydrology determines the flow characteristics of its river system. These flows define what the biological characteristics of that river will be, which in turn determine what kinds of habitat enhancement projects will succeed at various locations along a river. The study of the Elysian Valley included one full year of multi-taxa biological surveys, a historical ecology investigation of the Elysian Valley, and a review of historic and existing hydrological and hydraulic conditions. Major findings of this study are:
- Multiple Flow Scenarios = Uncertainty: There are currently multiple visions for the flow characteristics of the Los Angeles River as a whole due to differing management priorities of the agencies and stakeholders that have governance over different aspects of this hydrologic system. Bringing the various hydrologic plans and possibilities for the watershed into a single integrated vision of system flow characteristics will allow certainty and clarity at the site level for the design of habitat projects anywhere in the River system, including the Conservancy’s study area.
- Flows Drive Biology: The study area currently has higher flood and much higher dry weather flow rates than its historic condition. These high flow rates are supporting and encouraging non-native and invasive species. This leads to a lower level of biological diversity and resiliency than what would exist under lower flow rates, particularly during dry weather conditions.
- Prioritize Complementary Habitats: Enhancing and increasing the amount of perennial riparian habitat in-stream alone will not create as much biological value as identifying complementary enhancement opportunities outside of the River channel in adjacent upper terrace floodplain and upland habitats (e.g. alluvial scrub, mulefat scrub, willow scrub, oak-sycamore woodland, sage scrub, and grassland).
- River Adjacent Land Use: Land uses adjacent to the River and throughout the watershed are a part of the solution and part of the Los Angeles River’s biological and hydrologic system. The landscaping and hydrology of these areas should be designed to provide a value-added role to the habitat functions of the Los Angeles River ecosystem.
Next steps for advancing the discussion of habitat enhancement include working with local stakeholders and agencies to find consensus on a flow condition for the River and its Watershed as a whole. In the study area itself there are six complementary project opportunities that could be implemented in the near term to advance understanding of habitat enhancement for the Los Angeles River. These smaller, localized projects can be used as pilot projects for the complicated jurisdictional and regulatory processes that all future habitat projects will have to navigate. They will provide a manageable and controlled process that will bring the necessary agencies together to identify the most effective processes for future projects throughout the Los Angeles River ecosystem.
Groundwater Vulnerability Study Santa Clara County, California$0.00
Groundwater Vulnerability Study Santa Clara County, CaliforniaSanta Clara Valley Water District | October 18, 2010...Summary
The Santa Clara Valley Water District (District) is the primary water resources agency in Santa Clara County. This Groundwater Vulnerability Study was conducted...
The Santa Clara Valley Water District (District) is the primary water resources agency in Santa Clara County. This Groundwater Vulnerability Study was conducted to predict the vulnerability of groundwater to potentially contaminating land use activities to aid the District in its management and protection activities. Groundwater vulnerability is comprised of two key components: 1) groundwater sensitivity and 2) potentially contaminating activities. Groundwater sensitivity is generally defined as the relative ease with which a contaminant on or near the land surface can migrate to the aquifer of interest based on the intrinsic characteristics of the aquifer and the overlying unsaturated materials. Groundwater sensitivity is combined with the potentially contaminating activities risk to characterize overall groundwater vulnerability.
The Study Area is comprised of three groundwater subbasins: the Santa Clara, the Coyote, and the Llagas. Each has unique hydrogeologic characteristics as well as unique current and historic land uses. Water-bearing units in the Study Area have been grouped into two major aquifer systems, the Shallow Aquifer and Principal Aquifer. Groundwater vulnerability was assessed separately for each aquifer. Generally, the Shallow Aquifer occurs above regional confining layers. The Principal Aquifer lies beneath the Shallow Aquifer and supplies most of the groundwater produced for beneficial uses in the Study Area. The Principal Aquifer occurs under semi-confined to confined conditions. In areas where confining layers do not exist or are not laterally and vertically extensive, only the Principal Aquifer occurs. Accordingly, in the recharge zones, depth to water was characterized as the first encountered groundwater for both the Shallow and Principal aquifers. In contrast, the Shallow and Principal aquifers were uniquely defined in the confined areas with the Shallow Aquifer characterized by the first encountered groundwater and the Principal Aquifer defined by the top screened interval of wells tapping the primary groundwater production zone.
The southern area and lateral margins of the Santa Clara Subbasin are unconfined recharge areas. An extensive regional aquitard occurs in the northern interior portion of the subbasin. The Santa Clara Subbasin is currently highly developed with residential, commercial, and industrial areas. Due to the high density of urban land uses including major industrial manufacturing and processing facilities, point-source contamination is prevalent but generally contained in the Shallow Aquifer. This is due, in part, to the protection offered by the significant confining layers found in the northern portion of the subbasin. The Santa Clara Subbasin is currently undergoing continued urban expansion and redevelopment of formerly industrial areas to residential use.
No significant laterally extensive confining layers exist in the Coyote Subbasin, and groundwater generally occurs under unconfined conditions. Compared with the Santa Clara Subbasin, the Coyote Subbasin is relatively rural, undeveloped, and mostly unincorporated with far fewer industrial/commercial contaminant release sites. Due to generally unconfined conditions, the Coyote Subbasin is hydrogeologically sensitive to groundwater contamination. Existing water quality impacts are related to agricultural practices and rural (e.g., septic) land use. Coyote Valley has a high potential for future residential and commercial development.
Groundwater in the Llagas Subbasin occurs under unconfined to confined conditions. Generally unconfined recharge areas are found in the northern portion of the subbasin, while confining layers become more frequent and laterally and vertically extensive in the southern areas. Accordingly, the northern portion of the subbasin is relatively more hydrogeologically sensitive to groundwater contamination compared with the southern subbasin. The Llagas Subbasin has urban development focused in the north and south with the central portion of the subbasin comprised predominantly of agricultural development and large residential parcels. The Llagas Subbasin is currently impacted by high levels of nitrate associated with rural land use and agriculture and perchlorate from historic releases from a flare manufacturer.
A comprehensive literature review was conducted to identify established methods to conduct vulnerability assessments. Based on the evaluation of available groundwater sensitivity assessment methods and an understanding of available hydrogeologic and water quality information for the Study Area, a statistical method was selected to quantify the sensitivity to contamination of the Shallow Aquifer and Principal Aquifer. Water quality data (i.e., nitrate concentrations and distribution) were used for calibration and verification purposes to identify and rank groundwater sensitivity factors. Based on the logistic regression statistical analysis, four factors were found to be the most important in characterizing groundwater sensitivity. These include 1) soil media characteristics in the vadose zone, 2) groundwater recharge, 3) depth to top of screen, and 4) annual groundwater production. Groundwater recharge in the Study Area includes a significant amount of artificial recharge conducted by the District. Traditionally, artificial recharge and groundwater production would not be considered intrinsic aquifer characteristics. However, for this Study, groundwater sensitivity did include consideration of quasiintrinsic characteristics such as artificial recharge and production. In addition to the objective statistical analysis, subjective refinements relative to artificial recharge areas and characterization of depth to water/aquifer were applied based on observation, technical judgment, and limitations in the nitrate data set. These refinements included subjectively ranking areas near artificial recharge areas as highly sensitive and using depth to first encountered groundwater to represent the depth to water factor for the Principal Aquifer in the recharge zones. This results in higher sensitivity in the recharge areas for the Principal Aquifer.
Figures ES-1 and ES-2 show the sensitivity of the Shallow and Principal aquifers, respectively. Not surprisingly, the sensitivity assessment found that the Shallow Aquifer is more sensitive than the Principal Aquifer.
In addition, the analysis indicates that the sensitivity of the Shallow and Principal aquifers is generally highest in the Llagas Subbasin, followed by the Coyote Subbasin, and Santa Clara Subbasin. Despite the protection afforded by the regional confining layer in the southern portion of the Llagas Subbasin, both the Shallow and Principal aquifers are highly sensitive to contamination due to high recharge rates and permeable soils. The sensitivity of the Shallow and Principal aquifers in the Coyote Subbasin are also relatively high due primarily to shallow aquifer conditions, high recharge rates, and large amounts of groundwater production. Although the confined zone in the Santa Clara Subbasin affords relatively good protection from surface contamination, the outer western confined zone appears to be highly sensitive to contamination due to the significant groundwater production in this area.
Unlike the sensitivity assessment, it is not possible to statistically calibrate potentially contaminating activities risk. Accordingly, potentially contaminating activities are commonly identified and ranked based on subjective observation and experience (e.g., California Drinking Water Source Assessment and Protection Program). For the potentially contaminating activities risk ranking, emphasis was placed on accurately characterizing the maximum risks so as not to underestimate potential risks.
The potentially contaminating activities risk analysis included four main risk factors or categories—general plan land use, potentially contaminating business activities, known contaminated sites, and supplemental data. Twenty-nine land use categories were selected and ranked with respect to groundwater impacts. Relative risk ranks were developed for 48 categories of business activities. Known and open contamination sites were given the highest ranking with a lower ranking for closed sites. Additional supplemental data for irrigated agriculture, septic system density, mines, landfills, and petroleum pipelines were also ranked and included in the analysis. These various risk factors were combined to generate the overall potentially contaminating activities risk distribution map. The potentially contaminating activities risk analysis found large portions of the Santa Clara Subbasin are at high risk due to its high level of development with commercial and industrial areas and many associated industrial and commercial contaminant release sites along with the lingering impacts of agricultural releases. Relatively lower overall risks are associated with the Coyote Subbasin, which is relatively rural, undeveloped, and mostly unincorporated with far fewer industrial/commercial contaminant release sites. Nonetheless, most of the subbasin shows a moderate level of risk associated with irrigated agriculture. It is important to note that the Coyote Valley has the most potential for future development and thus the most potential for an increase in risk in the future. Relatively lower overall potentially contaminating activities risk (compared with the Santa Clara Subbasin) is found in the Llagas Subbasin due to its more rural nature. Areas of relatively higher risk are associated with commercial and industrial development in the vicinity of the cities of Morgan Hill and Gilroy. Moderate risk is found in the central portion of the subbasin associated with irrigated agriculture. While continued conversion of rural to urban land use in the vicinity of the cities of Morgan Hill and Gilroy in the future will likely increase risk in these areas, the central portion of the subbasin is expected to remain relatively unchanged with respect to risk, given the established zoning.
The sensitivity assessment and potentially contaminating activities risk were combined to create the overall vulnerability maps for the Shallow and Principal aquifers. Figures ES-3 and ES-4 show the vulnerability of the Shallow and Principal aquifers, respectively. As might be expected, the vulnerability of the Shallow Aquifer is greater than the Principal Aquifer in areas of confinement in the Santa Clara Subbasin. The density of commercial/industrial sites and known contamination release sites in the northern Santa Clara Subbasin make the Shallow Aquifer highly vulnerable to contamination. The Principal Aquifer has fewer areas of very high vulnerability compared with the Shallow Aquifer due to the relative lower sensitivity of the Principal Aquifer.
The Llagas and Coyote subbasins exhibit high to very high groundwater vulnerability in both the Shallow and Principal aquifers. The high vulnerability is driven primarily by the high sensitivity in these two subbasins. Given the potential for future development in the Coyote Subbasin, the high degree of vulnerability of the subbasin requires the highest level of effort directed toward protection.
Following completion of the vulnerability assessment, a web-based geographical information system tool was developed, which incorporated the sensitivity, potentially contaminating activities risk, and vulnerability maps. Additional maps are also provided to enhance the usefulness of the tool. The tool enables District staff to work interactively with the vulnerability study analysis. The tool enables District staff to evaluate potential impacts of land use changes, prioritize basin management activities, prioritize review of known contamination sites, update existing data layers, update or modify risk factors, and add supplemental data layers.
Clean Water Act Jurisdiction Following the U.S. Supreme Court’s Decision in Rapanos v. United States & Carabell v. United States
Clean Water Act Jurisdiction Following the U.S. Supreme Court’s Decision in Rapanos v. United States & Carabell v. United StatesU.S. Environmental Protection Agency (EPA) | December 2, 2008...Summary
Congress enacted the Clean Water Act ("CWA" or "the Act") "to restore and maintain the chemical, physical, and biological integrity of the Nation's...
Congress enacted the Clean Water Act ("CWA" or "the Act") "to restore and maintain the chemical, physical, and biological integrity of the Nation's waters." One of the mechanisms adopted by Congress to achieve that purpose is a prohibition on the discharge of any pollutants, including dredged or fill material, into "navigable waters" except in compliance with other specified sections of the Act.
In most cases, this means compliance with a permit issued pursuant to CWA §402 or §404. The Act defines the term "discharge of a pollutant" as "any addition of any pollutant to navigable waters from any point source" and provides that "[t]he term `navigable waters' means the waters of the United States, including the territorial seas[,]."
In Rapanos, the Supreme Court addressed where the Federal government can apply the Clean Water Act, specifically by determining whether a wetland or tributary is a "water of the United States." The justices issued five separate opinions in Rapanos (one plurality opinion, two concurring opinions, and two dissenting opinions), with no single opinion commanding a majority of the Court.
The Rapanos Decision
Four justices, in a plurality opinion authored by Justice Scalia, rejected the argument that the term "waters of the United States" is limited to only those waters that are navigable in the traditional sense and their abutting wetlands. However, the plurality concluded that the agencies' regulatory authority should extend only to "relatively permanent, standing or continuously flowing bodies of water" connected to traditional navigable waters, and to "wetlands with a continuous surface connection to" such relatively permanent waters .
Justice Kennedy did not join the plurality's opinion but instead authored an opinion concurring in the judgment vacating and remanding the cases to the Sixth Circuit Court of Appeals. Justice Kennedy agreed with the plurality that the statutory term "waters of the United States" extends beyond water bodies that are traditionally considered navigable." Justice Kennedy, however, found the plurality's interpretation of the scope of the CWA to be "inconsistent with the Act's text,structure,andpurpose[,]" and he instead presented a different standard for evaluating CWA jurisdiction over wetlands and other waterbodies.' Justice Kennedy concluded that wetlands are"waters of the United States" "if the wetlands, either alone or in combination with similarly situated lands in the region, significantly affect the chemical, physical, and biological integrity of other covered waters more readily understood as `navigable.' When, in contrast, wetlands' effects on water quality are speculative or insubstantial, they fall outside the zone fairly encompassed by the statutory term 'navigable waters.'
Four justices, in a dissenting opinion authored by Justice Stevens, concluded that EPA's and the Corps' interpretation of "waters of the United States" was a reasonable interpretation of the Clean Water Act.
When there is no majority opinion in a Supreme Court case, controlling legal principles may be derived from those principles espoused by five or more justices. Thus, regulatory jurisdiction under the CWA exists over a water body if either the plurality's or Justice Kennedy's standard is satisfied. Since Rapanos, the United States has filed pleadings in a number of cases interpreting the decision in this manner.
The agencies are issuing this memorandum in recognition of the fact that EPA regions and Corps districts need guidance to ensure that jurisdictional determinations, permitting actions, and other relevant actions are consistent with the decision and supported by the administrative record. Therefore, the agencies have evaluated the Rapanos opinions to identify those waters that are subject to CWA jurisdiction under the reasoning of a majority of the justices. This approach is appropriate for a guidance document. The agencies will continue to monitor implementation of the Rapanos decision in the field and recognize that further consideration of jurisdictional issues, including clarification and definition of key terminology, may be appropriate in the future, either through issuance of additional guidance or through rulemaking.
Initial Characterization of the Groundwater System near the Lower Colorado Water Supply Project, Imperial Valley, California$0.00
Initial Characterization of the Groundwater System near the Lower Colorado Water Supply Project, Imperial Valley, CaliforniaU.S. Geological Survey (USGS) | October 13, 2015...Summary
In 2009, the U.S. Geological Survey, in cooperation with the city of Needles, began a study of the hydrogeology along the All-American Canal,...
In 2009, the U.S. Geological Survey, in cooperation with the city of Needles, began a study of the hydrogeology along the All-American Canal, which conveys water from the Colorado River to the Imperial Valley.
The focus of this study was to gain a better understanding of the effect of lining the All-American Canal, and other management actions, on future total dissolved solids concentrations in groundwater pumped by Lower Colorado Water Supply Project wells that is delivered to the All-American Canal. The study included the compilation and evaluation of previously published hydrogeologic and geochemical information, establishment of a groundwater-elevation and groundwater-quality monitoring network, results of monitoring groundwater elevations and groundwater quality from 2009 to 2011, site-specific hydrologic investigations of the Lower Colorado Water Supply Project area, examination of groundwater salinity by depth by using time-domain electromagnetic surveys, and monitoring of groundwater-storage change by using microgravity methods.
Prior to the completion of the All-American Canal in 1940, groundwater in the study area flowed from east to west, and groundwater was recharged primarily by underflow from the Colorado River Valley. After construction of the All-American Canal, groundwater elevations were altered in the study area as seepage of Colorado River water from the All-American Canal and other canals became the dominant recharge source. By 2005, groundwater elevations had increased by as much as 50–70 feet along the All-American Canal.
Superimposed on the east-to-west groundwater gradient was groundwater movement away from the All-American Canal to the north and, most likely, to the south into Mexico. After lining the All-American Canal, from 2007 to 2010, groundwater elevations declined as seepage from the All-American Canal decreased. Between 2005 (the last complete groundwater-elevation survey prior to lining the All-American Canal) and 2011, groundwater elevations declined 20–40 feet along the All-American Canal and as much as 40–45 feet in the vicinity of Lower Colorado Water Supply Project pumping wells.
Water-quality and isotope data were used to differentiate historically recharged groundwater from groundwater more recently recharged by seepage of Colorado River surface water from the All-American Canal. Prior to the completion of the All-American Canal in 1940, groundwater in the southern part of the study area was primarily sodium-chloride/sulfate type water that had relatively low total dissolved solids concentrations (500–820 milligrams per liter). During 2007–11, groundwater in the southern part of the study area, near the All-American Canal, ranged from sodium-chloride type water to mixed-cation-sulfate type water that had total dissolved solids concentrations generally less than 879 milligrams per liter.
The stable-isotopic signature of groundwater near the All-American Canal sampled in 2009–11 indicated inputs of Colorado River water that had been affected by evaporation, and radioactive isotopes indicated that a substantial fraction of water had been recharged recently, within the past 60 years. This contrasted with historically recharged groundwater near the All-American Canal, which had higher sodium and chloride concentrations, and lower calcium and sulfate concentrations, than recent recharge from the All-American Canal.
Groundwater at a distance from the All-American Canal, in the East Mesa, Algodones Dunes, Pilot Knob Mesa, and Cargo Muchacho Mountains piedmont, was found to have higher total dissolved solids concentrations (generally greater than 1,000 milligrams per liter) than recently recharged groundwater near the All-American Canal. Time-domain electromagnetic data indicated that low-salinity groundwater was present down to about 377 feet below land surface near the All-American Canal; groundwater salinity at depth increased with distance north from the All-American Canal. Groundwater several miles or more from the canal also did not contain tritium and had a residence time on the order of thousands to tens of thousands of years. The groundwater in the piedmont of the Cargo Muchacho Mountains had a distinctly light stable-isotopic signature indicative of recharge by runoff from local precipitation, whereas the stable isotopic signature of groundwater in the East Mesa and the Algodones Dunes indicated a mixture of local precipitation and historic Colorado River recharge sources.
During and after lining the All-American Canal (2007–11), groundwater elevations in the Lower Colorado Water Supply Project area declined, while total dissolved solids concentrations remained relatively constant. The total dissolved solids concentrations in well LCWSP-2 ranged from 650 to 800 milligrams per liter during this study. Depth-specific water-quality and isotope sampling at well LCWSP-2 indicated the groundwater pumped from the deeper part of the screened interval (240–280 feet below land surface) contained a greater proportion of historical groundwater than the groundwater pumped from the shallower part of the screened interval (350–385 feet below land surface). Age-tracer data at well LCWSP-2 indicated that all depths of the screened interval had received recent recharge from seepage of Colorado River water from the All-American Canal.