BILL ANALYSIS �
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| SENATE COMMITTEE ON NATURAL RESOURCES AND WATER |
| Senator Fran Pavley, Chair |
| 2013-2014 Regular Session |
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BILL NO: SB 1259 HEARING DATE: April 29, 2014
AUTHOR: Pavley URGENCY: No
VERSION: April 3, 2014 CONSULTANT: Dennis O'Connor
DUAL REFERRAL: No FISCAL: Yes
SUBJECT: Desiltation Studies.
BACKGROUND AND EXISTING LAW
1.Under current law, the Department of Water Resources (DWR),
under the police power of the state, supervises the
construction, enlargement, alteration, repair, maintenance,
operation, and removal of dams and reservoirs for the
protection of life and property. To this end, DWR is
authorized to initiate investigations and gather data as
needed to study of the various features of the design and
construction of dams, reservoirs, and associated facilities.
2.Current law establishes as the policy of the state that The
California Water Plan, as amended, is accepted as the master
plan which guides the orderly and coordinated development,
management, and efficient utilization of the water resources
of the state. DWR is required to update the California Water
Plan quinquennially (every 5 years).
As part of updating The California Water Plan, DWR is required
to conduct a study to determine the amount of water needed to
meet the state's future needs and to recommend programs,
policies, and facilities to meet those needs.
One year before issuing each update to The California Water
Plan, DWR is required to release a preliminary draft of the
assumptions and other estimates upon which the study will be
based, to interested persons and entities throughout the state
for their review and comments. Existing law prescribes a broad
list of subjects which DWR is required to release those
assumptions and estimates. These include topics such as
hydrology, groundwater conditions, land use patterns, levels
of conservation, demographic projections, etc.
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3.In 2009, Water Resources Research published a paper by J. Toby
Minear and G. Matt Kondolf titled "Estimating reservoir
sedimentation rates at large spatial and temporal scales: A
case study of California." Based on their modeling, the
authors estimated "[s]tatewide reservoirs have likely filled
with 2.1 billion m3 of sediment to date, decreasing total
reservoir capacity by 4.5%. About 200 reservoirs have likely
lost more than half their initial capacity to sedimentation."
2.1 billion m3 of sediment is equivalent to about 1.7 million
acre-feet.
PROPOSED LAW
This bill would do three things.
1.Authorize DWR to initiate investigations and gather data as
needed to study the loss of storage capacity behind dams
resulting from siltation.
2.Require DWR to complete an initial study by January 1, 2017,
and further require that the study include an evaluation of
cost-effective strategies for sediment removal, relative to
the costs of alternative methods of flood protection and water
supply.
3.Require that the results of any siltation study be reflected
in the quinquennial update of the California Water Plan.
ARGUMENTS IN SUPPORT
According to the author, "Studies suggest that the state's
reservoirs have lost a significant amount of storage capacity
due to siltation. Restoring that storage capacity could greatly
increase the state's ability to store water; potentially by
millions of acre-feet. Unfortunately, we don't have sufficient
information to know which reservoirs are most impacted and which
have the greatest potential for cost-effective sediment removal.
"SB 1259 addresses this problem by directing DWR to study the
loss of storage capacity behind dams resulting from siltation.
The initial study is to be completed by January 2017, and
include an evaluation of cost-effective strategies for sediment
removal, relative to the costs of alternative methods of flood
protection and water supply. This information would then be
used to help update the California Water Plan."
ARGUMENTS IN OPPOSITION: None
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COMMENTS
Sedimentation A Real Problem In LA Co. According to the Los
Angeles County Department of Public Works (DPW), "The 2009
Station Fire was the largest fire in the Los Angeles County
recorded history and burned over 160,000 acres before
containment. Generally, it takes five years or more for a
watershed to recover from a wildfire. Heavy sedimentation from
the denuded ground surface is expected to accumulate in the Los
Angeles County Flood Control District's reservoirs during the
recovery period which will reduce the reservoirs' storage
capacity and potentially cover and/or damage dam outlet works
critical for flood control. Several of the District's reservoirs
have been impacted by this sedimentation and require immediate
attention. Over the next several years, the District will strive
to maintain operations by removing sediment from the reservoirs.
This will restore flood capacity and full operability of the
outlet works as well as maximize water conservation efforts."
DWP has sediment removal projects for:
Big Tujunga Dam and Reservoir
Cogswell Dam and Reservoir
Devil's Gate Dam and Reservoir
Morris Dam and Reservoir
Pacoima Dam and Reservoir
Little Real Data. According to a 2011 article by Matt Weiser in
the High Country News, "Utah is one of the few Western states
that have even attempted to assess sedimentation. In a March
2010 report, the state's Department of Water Resources estimated
that in 40 years, Utah's total storage capacity will have
declined 25 percent. Its reservoirs lose about 12,340 acre-feet
a year to sedimentation, yet the state needs about double that
amount annually in additional supply to keep up with population
growth. The reservoirs 'cannot be considered renewable resources
unless sedimentation is adequately addressed,' the report
states."
"But Utah was able to find data for only 18 of its 133
reservoirs larger than 1,000 acre-feet. Nationally, the state of
knowledge is equally poor. John Gray, a hydrologist at the U.S.
Geological Survey in Reston, Va., manages the nation's only
large database on reservoir sedimentation, which includes
surveys of 1,824 large and small reservoirs across the country
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compiled by the Soil Conservation Service, now the Natural
Resources Conservation Service."
"Most of the surveys are much older than [the Bureau of
Reclamation's] and haven't been updated in at least two decades;
many were completed using crude techniques - measuring reservoir
depth with weighted rope, or noting how much piano wire sank to
the bottom from a boat crossing a known transect. As a result,
it's hard to know for sure how rapidly the nation's reservoirs
are filling, or how full they are. 'We're just not even the tip
of the iceberg here,' Gray says. 'We should be ... getting a lot
more data on this, and where there are problems, start alerting
those locations. There's time to address this.' "
Related Measures:
AB 2725 (Brown) - among other things, would require DWR, as a
part of updating the California Water Plan, to include
assumptions and estimates regarding urban waterway
restoration.
SUGGESTED AMENDMENTS: None
SUPPORT:
Sierra Club California
OPPOSITION: None Received
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