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Effects of Stormwater Capture and Use on Urban Streamflows
Abstract
Cities across the globe manage stormwater to enhance water supplies. Capturing and using stormwater in urban watersheds can have benefits for groundwater recharge, reduced pollutant loading in downstream watersheds, and habitat management. In California, metropolitan areas in the southern coastal regions of the state have for decades captured an average of 493 Million Cubic Meters (400,000 acre-feet) of runoff annually to recharge groundwater. But in a state with highly managed watersheds and seasonal precipitation, capturing stormwater for water supply goals can affect urban streamflows. Using a model with simulation and optimization of regional urban water resources management in Los Angeles County (Artes), we analyze the potential effects of increasing stormwater capture and infiltration on urban streamflow volumes. Results indicate that for many watersheds in LA, further increasing stormwater capture and use would significantly reduce urban streamflow volumes, especially in downstream basins. But in some basins, streamflows are increased to preferentially direct water to existing stormwater capture basins. Results illustrate potential tradeoffs in water supply, in-stream water flows, and aquatic habitat that must be considered when looking to increase use of local water sources through more stormwater capture.
... While stormwater capture is advancing throughout the state, and considered part of more sustainable water management, there are important trade-offs that must be considered when pursuing stormwater capture over other water management options. Porse and Pincetl (2018) demonstrated that increasing stormwater capture and use could significantly reduce stream flows, negatively affecting aquatic habitats and downstream communities [22]. The location and context of the specific projects must be considered as part of analysis on multiple benefits and costs of stormwater capture. ...
... While stormwater capture is advancing throughout the state, and considered part of more sustainable water management, there are important trade-offs that must be considered when pursuing stormwater capture over other water management options. Porse and Pincetl (2018) demonstrated that increasing stormwater capture and use could significantly reduce stream flows, negatively affecting aquatic habitats and downstream communities [22]. The location and context of the specific projects must be considered as part of analysis on multiple benefits and costs of stormwater capture. ...
Urban stormwater is increasingly being considered a viable alternative water supply in California and throughout the southwestern U.S. However, current economic analyses of stormwater capture do not adequately examine differences in stormwater project types and do not evaluate co-benefits provided by the projects. As a result, urban stormwater capture is undervalued as a water supply option. To advance economic analyses of stormwater capture, we determined the levelized cost of water in U.S. dollar per acre-foot of water supply (AF; 1 AF = 1233.5 m³) for 50 proposed stormwater capture projects in California, characterizing the projects by water source, process, and water supply yield. In addition, we incorporated reported co-benefits of projects into the analysis to determine the net benefit of proposed projects. Proposed urban stormwater capture projects were more expensive than non-urban stormwater capture projects on a per-volume basis ($1,180 per AF and $531 per AF, respectively); however, this was primarily driven by the relatively large size of the non-urban stormwater capture projects examined. When incorporating the limited number of reported co-benefits of the projects, the expected levelized cost of water from urban stormwater capture projects decreased dramatically. For projects that reported even a limited number of additional benefits, the net levelized cost decreased from $1,030 per AF to $150 per AF, with some of the projects demonstrating a net benefit. Thus, scaling urban stormwater capture projects to capitalize on economies of scale and incorporating co-benefits of projects can dramatically improve the economic feasibility of these projects. This work demonstrates that stormwater capture can present a cost-effective water supply option in California, and that beyond California, fairer comparisons among projects and inclusion of co-benefits can provide decision makers with adequate information to maximize investments in water management.
... Permeable pavements are one of the most used compensatory techniques for stormwater runoff control worldwide, fostering the reduction of water flow to the public drainage system [1][2][3] and the discharge of pollutants into receiving water bodies [4,5], beyond favoring the recharge of groundwater aquifers [6]. Additionally, the filtration of solids and solid-bound contaminants in permeable pavements enables water purification (physical, chemical, and biological), improving the stormwater runoff quality [7]. ...
This paper aims to advance the state of the art of pervious concrete design based on the paste-thickness approach by investigating critical design parameters that influence the mixture functionality. The discussions focus on the influence of granulometric composition and superplasticizer on the aggregate packing and the binder drainage test response. The results show that the superplasticizer influenced the binder drainage test response by increasing the cement consumption and reducing the w/c ratio and cementitious paste thickness, with no significant impact on the hydraulic conductivity of the pervious concrete mixtures. The maximum aggregate size influenced the compressive strength results regardless of the superplasticizer content. The larger the aggregate size, the higher the compressive strength, decreasing the air voids content and hydraulic conductivity. Larger aggregate size resulted in pervious concrete mixtures with better resistance to degradation, especially for single-sized and discontinuous granulometry. The aggregate size ratio influenced the functionality of the pervious concrete due to the smaller aggregates that probably filled the voids left by the larger ones, reducing the porosity and, consequently, the permeability of the mixtures. Uniform granulometry (single-sized grain) prevented the granular packing and increased air voids’ size and quantity. Continuous granulometry resulted in low air voids content but large pores size due to the better granular packing. The paper advances the state of the art by broadening the applicability of the paste thickness-based design approach for a wide range of granulometric compositions, different aggregate size ranges, and the use of superplasticizers.
... Permeable pavements that allow water infiltration are one of the most used compensatory techniques for stormwater runoff control by reducing water flow to the public drainage system (Bentarzi et al. 2016;Kayhanian et al. 2019;Vaz et al. 2020), reducing the discharge of pollutants into receiving water bodies (Castillo-Rodríguez et al. 2021;Kamali et al. 2017), and recharging groundwater aquifers (Porse and Pincetl 2019). The filtration of solids and solid-bound contaminants in permeable pavements improves the quality of stormwater runoff (Weiss et al. 2019). ...
This paper investigates the viability of recycling construction and demolition waste as aggregate in porous asphalt pavement for stormwater runoff management. The influence of granulometric composition, recycled aggregate content (0%, 12.5%, 25%, and 37.5%), and binder content (4% to 6%) was investigated. A comprehensive characterization to identify the minimum binder content that might ensure a suitable hydraulic conductivity with minimum influence in the mechanical properties and moisture-induced damage was performed. The tested mixtures presented suitable particle loss, tensile strength, moisture-induced damage, and hydraulic conductivity for application as porous asphalt mixture for urban stormwater runoff management. The use of recycled aggregate resulted in acceptable air voids content only in mixtures produced with a binder content of 4.5%. The porous asphalt mixture produced with granulometric composition GC3, 25% recycled aggregate, and 4.5% asphalt binder could be potentially used for the intended application in stormwater runoff management.
... In particular, recent writings from the research group of UCLA's Stephanie Pincetl suggest a coming conflict. Using a combination of socio-technical system analysis and hydrological modeling, these researchers find that management policies designed to maximize stormwater capture will adversely affect stream flows within the LA basin's watersheds, suggesting the need to accept tradeoffs between riparian habitat preservation and local water supply maximization (Mika, Gallo, and Porse 2018;Pincetl et al. 2019;Porse and Pincetl 2018). While noting the need for further study to adequately characterize the effects of new water management techniques on the local flow regime, this body of research highlights the inherent conflict between projects of riverscape restoration, or even preservation, and water supply enhancement. ...
Long a contested environment, Los Angeles’s eponymous, concrete-lined river underwent a significant transformation in 2010. Following a protracted review, the United States Environmental Protection Agency changed the river’s classification from a federally managed flood control channel to “traditional navigable waterway of the United States”, as defined by the federal Clean Water Act. Southern California’s environmentalist community celebrated this long-desired legal shift, which placed the river squarely in the public – and publicly accessible – domain. In the years that followed, this community’s discourse and practice around the river have developed around a pair of related-yet-divergent notions of this peculiar urban riparian environment. For some, the waterway is framed as a place to be sustained, restored, and made accessible to residents as unconventional ‘natural’ space and a valuable recreational amenity. Among others, it is understood as an underutilized source of a vital, scarce resource for the city: water. Drawing on long-term participant observation among Los Angeles-based environmental activists, NGO workers, and water managers, this chapter explores the social, material, and legal practices that have accreted around these interpretations of the river.
... The model simulation and optimization of regional urban water resources management were utilized to analyze the potential influence on urban streamflow volumes by increasing stormwater capture and infiltration, in Los Angeles County, USA (Porse & Pincetl, 2018). The results showed that the urban streamflow volumes significantly decreased with the increase of stormwater capture, especially in downstream basins. ...
A comprehensive review of the research papers published in 2018 focusing on nonpoint source (NPS) pollution is presented in this review article. The identification of pollution from different sources and estimation of NPS pollution using various models are summarized in this review paper. Various innovative techniques are also examined to abate NPS pollution.
Practitioner points
The non‐point source pollution in 2018 is systematically reviewed and documented.
This review evaluates and summarizes the identification, quantification, reduction, and management of NPS pollution.
Future perspectives of NPS pollution research are discussed.
... But tradeoffs exist. For instance, capturing, and using more stormwater for groundwater recharge may reduce flows in the highly channelized urban streams of LA County (Porse and Pincetl 2018). The LA River basin, in particular, is a useful case study in examining these tradeoffs. ...
Acute water shortages for large metropolitan regions are likely to become more frequent as climate changes impact historic precipitation levels and urban population grows. California and Los Angeles County have just experienced a severe four year drought followed by a year of high precipitation, and likely drought conditions again in Southern California. We show how the embedded preferences for distant sources, and their local manifestations, have created and/or exacerbated fluctuations in local water availability and suboptimal management. As a socio technical system, water management in the Los Angeles metropolitan region has created a kind of scarcity lock-in in years of low rainfall. We come to this through a decade of coupled research examining landscapes and water use, the development of the complex institutional water management infrastructure, hydrology and a systems network model. Such integrated research is a model for other regions to unpack and understand the actual water resources of a metropolitan region, how it is managed and potential ability to become more water self reliant if the institutions collaborate and manage the resource both parsimoniously, but also in an integrated and conjunctive manner. The Los Angeles County metropolitan region, we find, could transition to a nearly water self sufficient system.
Studies on water quality are necessary, as catchments of small watercourses are exposed to anthropogenic influences associated with agricultural activities, settlement, transport and other undertakings, leading to water pollution. There has been insufficient research performed on the valley’s ability to retain nutrients during floods, contributing to water accumulation. The main object of the study was to identify the retention capacity of river valleys under various aspects of human urbanization. To represent soil water retention, the Soil Conservation Service Curve Number (SCS-CN) method was used. Spatiotemporal autoregressive models were exploited to investigate the relationship between pollutants in precipitation and surface water in rivers. In contrast, multivariate analysis was used to identify and reveal patterns of land use for specific chemical compounds in the headwaters. The canonical-correlation analysis (CCA) showed that Mg+2 and Ca+2 cations in rainwater and surface waters play the main roles in the geochemical cycle in urban and rural areas. In the urban catchment area, the strongest relations were found for NO3−, K+ and Na+. The average NO3− concentration in urban headwater was 8.3 mg·dm−3, the highest in the study area. The relationship between NO3− concentration in headwater and rainwater was found for all study catchments using spatial autoregression (SAR). High concentrations of SO42− in surface water have been identified in urban areas. Severe water erosion raises the risk of nutrient leaching in soils prone to surface runoff. As a consequence of low soil permeability and urbanization, retention capacity is significantly reduced in areas with low soil permeability. Land development plans should take spatial retention capacity into consideration. To ensure that large reservoirs can retain water in the face of climate change, riparian buffer zones (protective zones in valleys for small water bodies as well as Nature-based Solution) are important.
Federal regulations for municipal separate storm sewer systems (MS4s) in the United States have been in place since 1990 as part of the Nation Pollutant Discharge Elimination System (NPDES), aiming to reduce sediment and pollutant loads originating from urban areas. However, small-municipality (Phase II) MS4s frequently grapple with several challenges, resulting in a lack of stakeholder buy-in and actionable stormwater management plans. We identify five common challenges concerning MS4 requirements based on literature review, professional experience, and feedback solicited from stakeholders, municipal managers, and fellow professionals and offer real-world examples of efficient, effective MS4 frameworks and/or solutions. The five challenges are summarized as beliefs that: (1) agricultural land use is the largest pollutant contributor and the root cause of pollution problems; (2) stormwater management only benefits downstream communities; (3) large, expensive projects are required to comply with regulations; (4) maintenance, monitoring, and inspection of best management practices (BMPs) is overwhelmingly complex and expensive; and (5) a lack of direct funding makes complying with regulations an impossible task. These challenges are universal in nature for Phase II MS4 permittees and can create real barriers for effective stormwater management. However, we found many examples of methods or techniques to effectively address these five specific challenges, making them well-suited and important for discussion. BMPs can create tangible improvements for surrounding communities (e.g., reduced streambank erosion and flooding), and improved understanding of the structure and options within the MS4 program will help small municipalities make informed choices about management plans.
Los Angeles imports water over long distances to supplement local supplies. Reduced reliability of the available imports is driving many local agencies to promote conservation and enhance local water sources. These include stormwater capture, water reuse and groundwater. But financial considerations are often a significant impediment to project development, especially when comparing new and existing sources. Here we demonstrate a comprehensive approach for evaluating the economic implications of shifting to local water reliance in Los Angeles County. We show that local water supplies are economically competitive. Results from integrated hydroeconomic modelling of urban water in Los Angeles identify cost-effective water supply portfolios and conservation targets. Considering costs across the ‘full-cycles’ of urban water supply that span agency boundaries yields better comparisons of planning alternatives. Throughout the region, many water retailers could successfully mitigate effects of imported water cuts while still supporting drought-tolerant landscapes, but some would suffer due to over-reliance on imports. Updating economic assessment methods would support needed innovations to achieve local reliance in Los Angeles, including infrastructure investments, institutional reforms, many more drought-tolerant landscapes and reallocated groundwater rights. A large-scale economic analysis of the economics of water supplies in the greater Los Angeles area, based on the ‘full-cycle’ costs of water sources such as imported water, groundwater, and reused and storm-water capture. The study showcases an updated model and framework for urban water studies that can be applied to other cities.
Integrated water management seeks to balance the interests of multiple stakeholders who desire many end-uses for water within the context of institutions and regulations. This problem is particularly complex in transboundary and water-scarce basins. In the Big Bend region of the Rio Grande/Bravo, an arid, monsoonal climate combines with multiple human and environmental water demands and established treaty requirements to stress available water resources. We analyzed reservoir operation strategies in the basin to integrate environmental flow (EF) considerations into existing management objectives using a linear programming model to assess reservoir operation policies. Five potential EF regimes are evaluated for improving aquatic and riparian habitat in the Big Bend region. The model uses the historical hydrologic record of river inflows, data for flood control and bi-national water allocation requirements, and parameters for human demands and infrastructure; to compare current and optimized operations of Luis L. Leon reservoir for multiple objectives. Results indicate that alternative operational policies for monthly reservoir storage (compared to historic values) can increase EF allocations without affecting water deliveries or treaty allocations. Some tradeoffs may exist, however, in managing reservoirs for both EFs and flood control. Our approach informs management strategies for the water-stressed basin that seek to incorporate environmental goals into existing infrastructure and operations.
The dominant source of coastal pollution adversely affecting the regional coastal water quality is the seasonally variable urban runoff discharged via southern California's rivers. Here, we use a surface transport model of coastal circulation driven by current maps from high frequency radar to compute two-year hindcasts to assess the temporal and spatial statistics of 20 southern California stormwater discharges. These models provide a quantitative, statistical measure of the spatial extent of the discharge plumes in the coastal receiving waters, defined here as a discharge's "exposure". We use these exposure maps from this synthesis effort to (1) assess the probability of stormwater connectivity to nearby Marine Protected Areas, and (2) develop a methodology to estimate the mass transport of stormwater discharges. The results of the spatial and temporal analysis are found to be relevant to the hindcast assessment of coastal discharges and for use in forecasting transport of southern California discharges.
Copyright © 2014 Elsevier Ltd. All rights reserved.
Streamflow augmentation has the potential to become an important application of recycled water in water scarce areas. We assessed the economic and ecological merits of a recycled water project that opted for an inland release of tertiary-treated recycled water in a small stream and wetland compared to an ocean outfall discharge. Costs for the status-quo scenario of discharging secondary-treated effluent to the ocean were compared to those of the implemented scenario of inland streamflow augmentation using recycled water. The benefits of the inland-discharge scenario were greater than the increase in associated costs by US$1.8M, with recreational value and scenic amenity generating the greatest value. We also compared physical habitat quality, water quality, and benthic macroinvertebrate community upstream and downstream of the recycled water discharge to estimate the effect of streamflow augmentation on the ecosystem. The physical-habitat quality was higher downstream of the discharge, although streamflow came in unnatural diurnal pulses. Water quality remained relatively unchanged with respect to dissolved oxygen, pH, and ammonia-nitrogen, although temperatures were elevated. Benthic macroinvertebrates were present in higher abundances, although the diversity was relatively low. A federally-listed species, the California red-legged frog (Rana draytonii), was present. Our results may support decision-making for wastewater treatment alternatives and recycled water applications in Mediterranean climates.
Environmental flow assessment frameworks have begun to consider changes to flow regimes resulting from land-use change. Urban stormwater runoff, which degrades streams through altered volume, pattern and quality of flow, presents a problem that challenges dominant approaches to stormwater and water resource management, and to environmental flow assessment. We used evidence of ecological response to different stormwater drainage systems to develop methods for input to environmental flow assessment. We identified the nature of hydrologic change resulting from conventional urban stormwater runoff, and the mechanisms by which such hydrologic change is prevented in streams where ecological condition has been protected. We also quantified the increase in total volume resulting from urban stormwater runoff, by comparing annual streamflow volumes from undeveloped catchments with the volumes that would run off impervious surfaces under the same rainfall regimes. In catchments with as little as 5-10% total imperviousness, conventional stormwater drainage, associated with poor in-stream ecological condition, reduces contributions to baseflows and increases the frequency and magnitude of storm flows, but in similarly impervious catchments in which streams retain good ecological condition, informal drainage to forested hillslopes, without a direct piped discharge to the stream, results in little such hydrologic change. In urbanized catchments, dispersed urban stormwater retention measures can potentially protect urban stream ecosystems by mimicking the hydrologic effects of informal drainage, if sufficient water is harvested and kept out of the stream, and if discharged water is treated to a suitable quality. Urban stormwater is a new class of environmental flow problem: one that requires reduction of a large excess volume of water to maintain riverine ecological integrity. It is the best type of problem, because solving it provides an opportunity to solve other problems such as the provision of water for human use.
Los Angeles, which relies on large infrastructure systems that import water over hundreds of miles, faces a future of reduced imports. Within Los Angeles and its hundreds of water agencies, the capacity to adapt to future changes is influenced by laws, institutions, and hydrogeology. This paper presents a systems analysis of urban water management in metropolitan Los Angeles County to assess opportunities for increasing local water reliance. A network flow model was developed to investigate management tradeoffs across engineered, social, and environmental systems. With an aggressive regional demand target, increased stormwater capture (300%), and prioritized water reuse from existing facilities, imported water supplies can be cut by 30% while maintaining landscapes, economic productivity, and groundwater resources. Further reducing imports (by 40-50%) is possible through actions to promote additional reuse, recharge, conservation, and groundwater access. Reducing imported water without significant conservation results in likely groundwater overdraft. Fragmented networks of agencies in Los Angeles create an uneven landscape of vulnerability to water shortages. The paper discusses model applications, research needs, and policy implications of results for dry-climate cities.
Los Angeles has a long history of importing water; however, drought, climate change, and environmental mitigation have forced the City to focus on developing more local water sources (target of 50% local supply by 2035). This study aims to improve understanding of water cycling in Los Angeles, including the impacts of imported water and water conservation policies. We evaluate the influence of local water restrictions on discharge records for 12 years in the Ballona Creek (urban) and Topanga Creek (natural) watersheds. Results show imported water has significantly altered the timing and volume of streamflow in the urban Ballona watershed, resulting in runoff ratios above one (more streamflow than precipitation). Further analysis comparing pre- vs. during-mandatory water conservation periods shows there is a significant decrease in dry season streamflow during-conservation in Ballona, indicating that prior to conservation efforts, heavy irrigation and other outdoor water use practices were contributing to streamflow. The difference between summer streamflow pre- vs. during-conservation is enough to serve 160,000 customers in Los Angeles. If Los Angeles returns to more watering days, educating the public on proper irrigation rates is critical for ensuring efficient irrigation and conserving water; however, if water restrictions remain in place, the City must take the new flow volumes into account for complying with water quality standards in the region.
Urbanization decreases the natural storage of a watershed, which changes the timing characteristics of the runoff. Stormwater management (SWM) basins are an attempt to put the storage lost through development back into the runoff process. While SWM basins provide the proper volume of storage, they fail to return the timing characteristics to those that existed prior to development. A study of a 2.12 sq mile watershed in Montgomery County, Md., showed that a SWM basin increased both peak flows and bedload transport rates in the channel downstream from the facility.- from ASCE Publications Abstracts
Studies have shown that the urbanization of a catchment can drastically
change the flood characteristics of a river. Published results are
synthesized to show the general relationship between the increase in
flood flows following urbanization and both the percentage of the basin
paved and the flood recurrence interval. In general, (1) floods with a
return period of a year or longer are not affected by a 5% paving of
their catchment, (2) small floods may be increased by 10 times by
urbanization, (3) floods with a return period of 100 yr may be doubled
in size by a 30% paving of the basin, and (4) the effect of urbanization
declines, in relative terms, as flood recurrence intervals increase.
In arid counties, such as Australia, the storage and extractive use of water is causing significant environmental damage and
traditional economic objectives of efficiency and maximising financial returns from surface water resources are often at conflict
the long-term sustainability of riverine ecosystems. Policy options for acquiring water to improve environmental flow regimes
include (a) reducing announced allocations, (b) recouping a proportion of traded water, and (c) have the government enter
the market and purchase water. This article makes a contribution to environmental water policy by quantitatively evaluating
and comparing these policy options for restoring environmental flow regimes. A case study of the Murrumbidgee Catchment located
in New South Wales, Australia is used to highlight the conflicts and tradeoffs between water management objectives in fully
allocated arid river basins.
KeywordsEnvironmental flows-Water trading-Environmental trader
The low impact development (LID) approach has been recommended as an alternative to traditional stormwater design. Research
on individual LID practices such as bioretention, pervious pavements, and grassed swales has increased in recent years. Bioretention
cells have been effective in retaining large volumes of runoff and pollutants on site, and consistently reduced concentrations
of certain pollutants such as metals. However, retention of certain pollutants such as nitrate–nitrogen and phosphorus has
been problematic. Porous pavements have been extremely effective in infiltrating stormwater runoff. Concerns have been raised
about groundwater contamination, but research has shown that this is not a problem in most settings. Green roofs have been
found to retain a large percentage of rainfall (63% on average) in a variety of climates. A common thread across bioretention,
green roofs and grassed swales was found: the export of phosphorus. The issue appears to be linked to high phosphorus levels
in the soil media, or possibly to fertilization of turf or planted areas. Solutions to this problem have been recommended.
Contrary to popular belief, research has shown that bioretention and pervious pavements continue to infiltrate even with frost
in the ground. Although issues have been identified with retention of certain pollutants, the LID approach has been found
to result in increased retention of stormwater and pollutants on site, mimicking pre-development hydrologic function. Future
research needs have also been identified.
The electronic version of this book has been prepared by scanning TIFF 600 dpi bitonal images of the pages of the text. Original source: Effluent America : cities, industry, energy, and the environment / Martin V. Melosi.; Melosi, Martin V., 1947-; xiii, 325 p. ; 24 cm.; Pittsburgh :; This electronic text file was created by Optical Character Recognition (OCR). No corrections have been made to the OCR-ed text and no editing has been done to the content of the original document. Encoding has been done through an automated process using the recommendations for Level 2 of the TEI in Libraries Guidelines. Digital page images are linked to the text file.
Garbage, wastewater, hazardous waste: these are the lenses through which Melosi views nineteenth- and twentieth-century America. In broad overviews and specific case studies, Melosi treats the relationship between industrial expansion and urban growth from an ecological perspective.
THE GREAT MORTALITY AMONG CHILDREN of the working class, and especially among those of the factory operatives, is proof enough of the unwholesome conditions under which they pass their first years. These influences are at work, of course, among the children who survive, but not quite so powerfully as upon those who succumb. The result in the most favourable case is a tendency to disease, or some check in development, and consequent less than normal vigour of the constitution. A nine-year-old child of a factory operative that has grown up in want, privation, and changing conditions, in cold and damp, with insufficient clothing and unwholesome dwellings, is far from having the working strength of a child brought up under healthier conditions. At nine years of age it is sent into the mill to work 61/2 hours (formerly 8, earlier still, 12 to 14, even 16 hours) daily, until the thirteenth year; then twelve hours until the eighteenth year. The old enfeebling influences continue, while the work is added to them. . . . but in no case can its [the child’s] presence in the damp, heavy air of the factory, often at once warm and wet, contribute to good health; and, in any case, it is unpardonable to sacrifice to the greed of an unfeeling bourgeoisie the time of children which should be devoted solely to their physical and mental development, and to withdraw them from school and the fresh air in order to wear them out for the benefit of the manufacturers. . . .
Development continues at a rapid pace throughout the country. Runoff from the impervious surfaces in these watersheds continues to be a major cause of degradation to freshwater bodies and estuaries. Low impact development techniques have been recommended to reduce these impacts. In this study, stormwater runoff and pollutant concentrations were measured as development progressed in both a traditional development, and a development that used low impact development techniques. Increases in total impervious area in each watershed were also measured. Regression relationships were developed between total impervious area and stormwater runoff/pollutant export. Significant, logarithmic increases in stormwater runoff and nitrogen and phosphorus export were found as development occurred in the traditional subdivision. The increases in stormwater runoff and pollutant export were more than two orders of magnitude. TN and TP export after development was 10 and 1 kg ha(-1) yr(-1), respectively, which was consistent with export from other urban/developed areas. In contrast, stormwater runoff and pollutant export from the low impact subdivision remained unchanged from pre-development levels. TN and TP export from the low impact subdivision were consistent with export values from forested watersheds. The results of this study indicate that the use of low impact development techniques on a watershed scale can greatly reduce the impacts of development on local waterways.
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Evaluating the effect of changes in flow and water temperature on stream habitats and communities in the Los Angeles/Ventura Region: Conceptual Approach and Summary of Available Data
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Stormwater and green infrastructure: the next generation of Los Angeles Stormwater infrastructure
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Effects of climate change on tidal marshes along a latitudinal gradient in California
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Intensive groundwater use in urban areas: the case of megacities
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Development of recommended flow targets to support biological integrity based on regional flow-ecology relationships for benthic macroinvertebrates in southern California streams
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