BACKGROUND
Through the Water Augmentation Study,
the Council for Watershed Health researches and demonstrates storm water infiltration solutions
to increase local supplies of water and reduce water quality impacts.
Overview
The Water Augmentation Study (WAS) is a long-term research project led by the Council
for Watershed Health, to explore the potential for increasing
local water supplies and reducing urban runoff pollution by increasing infiltration
of stormwater runoff. The project was initiated in January 2000, as a result of
a number of concerns:
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1. Impacts of urbanization on the LA region and the resulting increase in runoff
over time. Runoff volumes have increased tenfold over the past 75 years.
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2. Impacts of runoff-transported pollutants on rivers, coastal waters and beaches.
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3. Interest in utilizing this “wasted” resource as a potential addition to local
water supplies, in order to reduce reliance on declining supplies of imported water.
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4. Uncertainty surrounding the impacts of capturing polluted stormwater for infiltration,
in terms of both groundwater quality and quantity.
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The Los Angeles basin relies on
imported water for two-thirds of its water supply – sources which are becoming increasingly
restricted. In 2008, a combination of drought and regulatory restrictions has drastically
cut the amount of water available for import. As urbanization has increased the
area of paved surfaces over the past several decades, urban runoff has increased
tenfold. On average, about 500,000 acre-feet of runoff flows to the ocean annually
from the Los Angeles basin, about one-third of our annual water use.
Opportunities for additional surface water storage are limited in the developed
LA basin, but the groundwater aquifers have much unused capacity. If the questions
surrounding the feasibility of utilizing stormwater runoff for groundwater recharge
could be resolved, the result may be greater self-sufficiency for the Los Angeles
Basin in terms of water supply reliability.
The Council
for Watershed Health has forged a unique partnership between local water, public
works, and wastewater agencies, the State of California , and the US Bureau of Reclamation
to more fully evaluate capacity and feasibility of new stormwater management practices
through infiltration, and whether these can be achieved without impacting groundwater
quality. At the same time, we are evaluating the benefits of enhancing environmental
health, increasing green space in our neighborhoods, providing jobs, and increasing
our water supply reliability.
WEB LINKS
Water Augumentation Study
Elemer Avenue Retrofit
GWAM
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No Web Links Available for this project
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STUDY APPROACH
The Water Augmentation Study has
developed through three phases. The Phase 1 Pilot Study completed in 2002 began
an investigation of the groundwater quality ramifications of infiltrating stormwater,
by monitoring water quality at two sites in the Los Angeles area. Phase 2, completed
in 2007, expanded the study by adding four new sites and monitoring surface and
groundwater quality at all six locations. The monitoring program was structured
to assess infiltration characteristics and water quality ramifications of different
land use, soils, and types of Best Management Practices for infiltration. The data
from Phase 2 found that storm water infiltration did not negatively impact groundwater.
Phase 3 of our study is taking a closer look at the viability of region-wide infiltration
in terms of potential quantity, physical constraints, social and institutional issues,
and will compare the costs of developing this water supply relative to other possible
sources. Phase 3 incorporates a demonstration project on a neighborhood scale in
Sun Valley (The Elmer Avenue Neighborhood Retrofit), to show how existing infrastructure
can be retrofit to locally manage stormwater and incorporate a variety of other
sustainable watershed management practices. The overall goal of Phase 3 is to develop
a regional strategy for developing this potentially significant new source of water
for Southern California.
ELMER AVENUE RETROFIT
Through the Elmer Avenue Neighborhood Retrofit Project, the Council for Watershed Health and its partners are building the first “Green Street” in the City of Los Angeles to use bio-swales and an infiltration gallery under a street to address storm water. Designed to reduce flooding, improve water quality, and recharge our local groundwater supplies, the street demonstrates multiple alternative storm water best management practices (BMPs).
Based on the positive results of the Los Angeles Basin Water Augmentation Study, a one block section of Elmer Avenue in Sun Valley is being retrofit with state of the art BMPs to capture runoff, improve water conservation, reduce pollution to our rivers, restore habitat, provide green space, and beautify the community. Specific techniques include bio-swales and sub-surface galleries for infiltration, native drought-tolerant landscapes, smart-irrigation controllers, permeable surfaces, and solar street lights.
The demonstration project is being monitored to evaluate surface water quality improvements, quantify groundwater recharge, water conserved on landscapes, changes in property values, and additional multiple benefits. Homeowners are receiving training in the maintenance and care of their new landscapes over the course of the project. This neighborhood-scale project provides a real-world model of sustainable design and serves as an example to integrate many on-going efforts in the region to address flood management, water quality, local supplies, and environmental restoration.
Construction of the first phase of construction of the project was initiated in November 2008 and was completed in May 2010. The monitoring is continuing and the second phase of construction, the Elmer Paseo, is in progress. Check back here for updates on the materials to download including photos, plans, monitoring program and data, and the Elmer Paseo plans.
The Council for Watershed Health partnered with the City of Los Angeles, U.S. Bureau of Reclamation, Metropolitan Water District of Southern California, Water Replenishment District of Southern California, Los Angeles Department of Water and Power, County of Los Angeles Department of Public Works, TreePeople, Urban Semillas, and City of Santa Monica. Additional funding was provided by the California Department of Water Resources.
GWAM
The Ground Water Augmentation Model (GWAM), developed in partnership between the Council for Watershed Health and the US Bureau of Reclamation, estimates the amount of deep percolation (groundwater recharge) and storm water runoff generated within the urbanized portion of the Greater Los Angeles Region. Using runoff-diversion-to-infiltration scenarios, the model shows the potential increase in groundwater recharge given changes to the urban landscape.
Within an average year under baseline conditions, GWAM estimates that 16% of precipitation percolates past the root zone as deep percolation (~194,000 acre/feet) in the modeled area of Greater Los Angeles, while 48% of precipitation becomes runoff which flows into our existing storm systems, rivers, and ocean (~600,000 acre/feet). Further calculations indicate that if the first ¾” of runoff from storms on every parcel was conserved for infiltration there would be a potential increase of ~578,000 acre/feet/year to groundwater recharge, and stormwater runoff volume would potentially decrease to only 17% of precipitation (~206,000 acre/feet/year). This represents 384,000 acre/feet/year of additional groundwater recharge, a volume sufficient for the annual needs of three-quarters of a million (768,000) typical Southern California families (MWD, 2010).
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