Annex H: R DISTRICTS - Water Resources

Annex H: RECLAMATION DISTRICTS

Sacramento County (Reclamation Districts) Annex H.1 Multi-Hazard Mitigation Plan Update

September 2011

H.1 Introduction

This Annex details the hazard mitigation planning elements specific to Reclamation District 341,

800, and 1000, participating jurisdictions to the Sacramento County LHMP Update. This annex

is not intended to be a standalone document, but appends to and supplements the information

contained in the base plan document. As such, all sections of the base plan, including the

planning process and other procedural requirements apply to and were met by the Reclamation

Districts. This annex provides additional information specific to each district, with a focus on

providing additional details on the risk assessment and mitigation strategy for this community.

H.2 Planning Process

As described above, the reclamation districts followed the planning process detailed in Section

3.0 of the base plan. In addition to providing representation on the Sacramento County Hazard

Mitigation Planning Committee (HMPC), the District formulated their own internal planning

team to support the broader planning process requirements. Internal planning participants

included staff from the following District departments:

Reclamation District 1000 General Manager

Wagner & Bonsignore Engineering (for RD 341 and RD 800)

Additional details on plan participation and district representatives are included in Appendix A.

H.3 Community Profile

The community profile for the reclamation districts in Sacramento County is detailed in the

following sections. Figure H.1 displays a map and the location of the reclamation districts

within Sacramento County. RD 341 is circled in red, RD 800 is circled in yellow, RD 1000 is

circled in green. A more detailed map provided by RD 341 is shown in Figure H.2.


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Figure H.1. Reclamation Districts in Sacramento County

Source: Sacramento County LAFCO


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Figure H.2. RD 341 Boundaries

Source: RD 341


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H.3.1 History

RD 341

In the Delta, for the last 5,000 years to the 1850s, relative sea-level rise was balanced by vertical

marsh growth through biomass accumulation and sediment deposition. A transition from

deposition of organic silt-clay to peat formation in the Delta largely reflects the decline in

inundation frequency and the maturation of the marsh plain towards mean higher high water

elevations. The resulting freshwater tidal marshes developed because a relatively large

freshwater inflow compared to the size of the tidal prism sustained a low salinity, which

supported highly productive organic peat formation through tule growth. The large roots of the

tule created an organic fabric that supported and aided rapid vertical growth. The living surface

was maintained within the intertidal zone (natural habitat), and marsh organic accretion

(injection of roots and rhizomes, and incorporation of surface litter) was able to sustain vertical

growth at rates in excess of relative sea-level rise. The gradual accumulation of the organic and

inorganic sediment must have also offset the loss and compaction of existing peat.

The development of today’s Delta began in late 1850 when the Swamp and Overflow Land Act

conveyed ownership of tall swamp and overflow land, including Delta marshes from the federal

government to the State of California. Reclamation of Sherman Island began shortly thereafter,

and by 1859, local property owners had constructed small peat levees of three to four feet in

height, with a base width of about eight feet, along the banks of the Sacramento River and

Mayberry Slough.

Today, Sherman Island is protected by approximately 18-miles of levee which encompass

approximately 9,937 acres of land, according to the 1995 Sacramento Delta San Joaquin Atlas.

Approximately 9 miles of levee are project levee, constructed by the US Army Corps of

Engineers, and approximately 9 miles of levee are non-project levee. The entire levee system is

maintained by RD 341. RD 341 maintains and operates five modern pumping stations on

Sherman Island: three on the San Joaquin River (south) side; one on the Sacramento River

(north) side; and one on Sherman Island’s northwest corner. The pumps are part of a larger

system of pumps, siphons irrigation ditches and canals used to circulate water and drain the

Island

RD 800

Reclamation District No. 800 is an area within Sacramento County lying along the Cosumnes

River and was originally created by action of the California State Legislature in 1907 (Statutes

1907,Ch 213). This original District, comprised of 2,136 acres, is located between Deer Creek

and the Cosumnes River east of Elk Grove in Sacramento County. In January 1997, a flood of

extraordinary size occurred on the Cosumnes River between Sloughhouse and Wilton requiring

considerable construction work to levees along the river. However, no levee breaks occurred on

those maintained by Reclamation District 800.


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As a result of the 1997 flood on the Cosumnes River, it became apparent that a public agency

was needed to maintain the levees and facilities along the river between Sloughhouse and Wilton

areas, outside the boundaries of Reclamation District 800. At the request of landowners along

the Cosumnes River whose lands were not included within Reclamation District 800, the

Trustees of the District sought an amendment to the act under which the District was formed, in

order to modify the boundaries and incorporate additional lands on the right bank of the

Cosumnes River and to include, for the first time, lands on the left bank of the river down to the

vicinity of Wilton.

To accommodate the above additions of land, SB 437 (Senator Patrick Johnston) was introduced

and adopted by the Legislature and signed by the Governor as Chapter 191, Statutes of 1997.

This action provided for the increase in District acreage from 2,136 to 25,435 acres. The total

potential levee length is 34.05 miles with 17.65 miles along the right (or north) bank and 16.40

miles along the left (or south) bank.

Since the 1997 flood, with assistance from the County of Sacramento and funding by the U.S.

Department of Agriculture, repairs were completed to levees along the Cosumnes River.

RD 1000

Reclamation District No. 1000 was created by an act of the State Legislature on April 8, 1911.

The purpose was to allow for the reclamation of what was then known as the American Basin for

agricultural purposes. The American Basin historically flooded from the Sacramento and

American Rivers overflowing their banks due to winter rains and runoff from the foothills giving

it the rich fertile soil to support the agriculture which dominated the early years in Natomas.

Much of the land was owned by the Natomas Company of California. The Act gave the District

authority and responsibility for flood control and drainage in what has become the Natomas

Basin.

Reclamation of Natomas began in 1913 with construction of the perimeter levee system which

was completed in 1915. The original cost was approximately $2 million and was financed by the

sale of bonds. Some of these original bonds are still in the possession of the District. Following

completion of the levees, an interior drainage system consisting canals, ditches and drains was

constructed to collect both stormwater runoff from precipitation that falls within the leveed area

as well as agricultural runoff from irrigated farm land. The original system conveyed all the

runoff to a large pumping plant constructed in 1915 at the terminus of Second Bannon Slough

(Plant 1A). This plant still exists and is used today. It is located directly across the Garden

Highway from the District Office. A second pumping plant (Plant 2) was added at Pritchard

Lake in 1920 along the Sacramento River north of Elvertal Road, and a third plant (Plant 3) was

added in 1939 also located on the Sacramento River just north of San Juan Road. Eventually

five more pump plants were added at various locations in the District to accommodate more

development and relieve pressure on the original plants.


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The drainage system stayed in this configuration for a number of years. In the 1950’s and 1960’s

urbanization of the Natomas Basin began, predominantly because of its close proximity to

downtown Sacramento and the construction of the interstate highway system. The first area to

develop was the Gardenland area in the southern extremity of the basin tucked up against the

American River and Natomas East Main Drain Canal. In the 1960’s Sacramento Metropolitan

Airport was developed. A new pumping plant paid for by the County was constructed to handle

the increased runoff from the newly constructed airport.

Through the decades more development occurred starting with the South Natomas Community,

Arco Arena, and the surrounding areas. In the 1990’s North Natomas began developing bringing

thousands of new residents, businesses and supporting infrastructure. Industrial and commercial

development also expanded in the vicinity of the airport to support its growing needs. And the

airport itself has undergone and continues to undergo significant expansion to support the

growing passenger demands. In each case, the District worked with the appropriate agency to

insure the impacts of the development and increased runoff are mitigated and do not overburden

the existing drainage system. In most cases, large detention storage basins have been

incorporated into new development to temporarily store the increased urban runoff and allow it

to be bled back into our system at a rate similar to the pre-development condition. These

detention basins are augmented by improvements to the existing pumping plants to assist in

handling the increased urban runoff.

H.4 Hazard Identification and Summary

This section details how the risk varies across the Sacramento County planning area. Each

district’s planning team identified the hazards that affect the District and summarized their

frequency of occurrence, spatial extent, potential magnitude, and significance specific to each

district (see Table H.1). In the context of the plan’s planning area, there are no hazards that are

unique to the districts.

Information on past occurrences and the likelihood of future occurrences is detailed in Section 4,

Risk Assessment, of the base plan. Additional information for high and medium significant

hazards for the District is included in the Vulnerability Assessment section of this annex.


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Table H.1. RD 341 Hazard Summary

Hazard Frequency of Occurrence Spatial Extent

Potential Magnitude Significance

Agricultural Hazards: Insect Pests

Bird Strike

Dam Failure

Drought

Earthquake

Flood: 100/200/500-year Occasional Extensive Catastrophic High

Flood: Localized/Stormwater

Landslide

Levee Failure Occasional Extensive Catastrophic High

River/Stream/Creek Bank Erosion

Severe Weather: Extreme Heat

Severe Weather: Fog

Severe Weather: Freeze

Severe Weather: Heavy Rain and Storms

Likely Significant Critical Medium

Severe Weather: Tornadoes

Subsidence

Volcano

Wildfire

Guidelines for Hazard Rankings: Frequency of Occurrence: Highly Likely-Near 100 percent probability in next year Likely-Between 10 and 100 percent probability in next year or at least one chance in ten years Occasional-Between 1 and 10 percent probability in next year or at least one chance in next 100 years Unlikely-Less than 1 percent probability in next 100 years Spatial Extent: Limited-Less than 10 percent of planning area Significant-10-50 percent of planning area Extensive-50-100 percent of planning area

Potential Magnitude: Catastrophic-More than 50 percent of area

affected Critical-25 to 50 percent Limited-10 to 25 percent Negligible-Less than 10 percent

Significance (subjective): Low, Medium, High

Source: AMEC Data Collection Guide


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Bird Strike

Dam Failure

Drought

Earthquake

Earthquake: Liquefaction

Flood: 100/200/500-year Occasional Significant Catastrophic High


Landslide

Levee Failure Occasional Significant Catastrophic High


Highly Likely Significant Catastrophic High


Severe Weather: Fog




Subsidence

Volcano

Wildfire


Potential Magnitude: Catastrophic-More than 50 percent of area affected Critical-25 to 50 percent Limited-10 to 25 percent Negligible-Less than 10 percent Significance (subjective):

Low, Medium, High



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Bird Strike

Dam Failure Unlikely Extensive Critical Low

Drought

Earthquake

Earthquake: Liquefaction Unlikely Limited Limited Low

Flood: 100/200/500-year Likely Extensive Catastrophic High

Flood: Localized/Stormwater Occasional Limited Limited Medium

Landslide

Levee Failure Occasional Extensive Catastrophic Medium


Likely Significant Critical High


Severe Weather: Fog



Likely Limited Critical Medium


Subsidence

Volcano

Wildfire


Potential Magnitude: Catastrophic-More than 50 percent of area affected Critical-25 to 50 percent Limited-10 to 25 percent Negligible-Less than 10 percent Significance (subjective):

Low, Medium, High



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H.5 Vulnerability Assessment

The intent of this section is to assess each district’s vulnerability separate from that of the

planning area as a whole, which has already been assessed in Section 4.3 Vulnerability

Assessment of the base plan. This vulnerability assessment provides an inventory of the

population, property, and other assets located within the District and further analyzes those assets

at risk to identified hazards ranked of medium or high significance (as listed in Table H.1) to the

community. For more information about how hazards affect the County as a whole, see Chapter

4 Risk Assessment in the main plan.

H.5.1 Total Assets at Risk

This section identifies each district’s total assets at risk, including values at risk, critical

facilities, and infrastructure. Growth and development trends are also presented for the

community. This data is not hazard specific, but is representative of total assets at risk within a

community.

Values at Risk

Significant assets directly within the each district include a range of properties and infrastructure.

These may include District-owned property, critical facilities and infrastructure, cultural and

natural resources and others. An inventory of key district assets is provided in Table H.4, Table

H.5, and Table H.6. Total value of these assets exceeds $11.5 million for RD 341 (without the

value of the levees), $100 million for RD 800, and $2,061 for RD 1000.

Table H.4. Key Assets in RD 341

Name of Asset Facility Type Replacement Value Hazard Info

Agricultural High Potential Loss Facilities $6,132,830 Flood, Levee Failure

Agricultural-Irrigated from District Facilities

High Potential Loss Facilities $4,003,440 Flood, Levee Failure

Marina-Recreation High Potential Loss Facilities $14,980 Flood, Levee Failure

Urban High Potential Loss Facilities $79,510 Flood, Levee Failure

Commercial High Potential Loss Facilities $7,520 Flood, Levee Failure

Utilities (Including easements)

Transportation and Lifeline $558,300 Flood, Levee Failure

Source: RD 341



RD 800 levees Levee In excess of $100,000,000 Flood

Source: RD 800


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RD 1000 Plant 1A and 1B Essential $20 million Flood

RD 1000 Plant 2 Essential $5 million Flood






RD 1000 Levee system Essential $2 billion Flood

Sacramento International Airport

Transportation County Flood

City of Sacramento River Pump Stations (3)

Essential City Flood

City of Sacramento Drainage Pump Stations

Essential City Flood

Schools (2 high schools, middle and elementary

High Potential Natomas USD Flood

Fire Stations Essential City Flood

Senior Housing High Potential City Flood

Interstate 5 and 80 Highway 99

Transportation Caltrans Flood

Day Care Centers High Potential City Flood

Hazardous Material Sites High Potential City Flood

Source: RD 1000

H.5.2 Priority Hazards: Vulnerability Assessment

This section provides the vulnerability assessment, including any quantifiable loss estimates, for

those hazards identified above in Table H.1 as high or medium significance hazards. Impacts of

past events and vulnerability of the District to specific hazards are further discussed below (see

Section 4.1 Hazard Identification for more detailed information about these hazards and their

impacts on the Sacramento County planning area). Methodologies for calculating loss estimates

are the same as those described in Section 4.3 of the base plan. In general, the most vulnerable

structures are those located within the floodplain or within levee and dam inundation areas,

unreinforced masonry buildings, and buildings built prior to the introduction of modern building

codes.


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Flood

RD 341

Through discussion of the visual inspections, the District Board members, District

superintendent and District engineer have determined that Sherman Island levees are most

vulnerable to failure cause by flooding. Should a high water flood event cause levees to

collapse, Sherman Island would be fully inundated, risking the $11 million in district assets

discussed in Table H.4.

Areas of the existing levee system most susceptible to overtopping are those which do not meet

the PL 84-99 height standard. An inventory of levee sections and their respective heights is

maintained by the District. Analysis of this inventory shows that the levee along the San Joaquin

River from about levee station 330+00 to 510+00 contains stretches which are below the HMP

height standard (1 foot above 1:100 year flood event) and therefore are susceptible to

overtopping. Figure H.3 depicts levee flood protection levels for each individual section of the

Sherman Island levees.

Figure H.3. Level of Levee Flood Protection in Reclamation District 341

Source: Reclamation District 341 Five Year Plan (2009)


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RD 800

Flooding would occur as a result of levee failure or overtopping. Levee failure from either

breaching or overtopping would result in the total loss of levee embankment material, as was the

case in the 1997 flood event. Levee embankment failure within the current District boundary

from the 1997 event resulted in multiple levee failure sites along the Cosumnes River. The

resulting damage to agricultural lands was extensive, with the most damage occurring

immediately adjacent to the levee breach causing severe erosion to agricultural lands, deposition

of sands and debris and the complete destruction of adjacent vineyards and irrigation systems.

RD 1000

Currently no new development is allowed within Natomas due do the recent de-certification of

the perimeter levee system by FEMA. Levee improvements are under construction to restore the

levee system which would allow for additional development. The current general plans for the

City of Sacramento, Sacramento County, and Sutter County all anticipate significant future

development within Natomas pending completion of the levee improvements and improvements

in the economy.

As noted in this document, the current levee system does not meet the FEMA 100-year standard

and therefore the District is vulnerable to a catastrophic flood from the potential failure of the

perimeter levee system. The current population in Natomas is 100,000 based on the 2010 census

and the Corps of Engineer’s estimates total property damages (both public and private) would

likely exceed $10 billion.

The District has eight pump stations in the interior basin used to pump the stormwater and

agricultural runoff from the basin into the adjacent riverine system. A catastrophic levee failure

could eventually damage all eight of the pump stations and require their reconstruction. Table

H.6 shows the estimated replacement cost for each of the pump stations. In addition, the District

has a corporation yard and a main office in Natomas. The main office is located on top of the

existing Sacramento River levee and would likely not be physically damaged by a catastrophic

flood event though it would not be functional due to loss of utilities including power as a result

of the flood. The corporation yard would be damaged due to a flood event and could result in a

loss of the District’s equipment fleet unless it can be relocated to high ground before flood

waters affect the corporation yard. This would be dependant on the location of a levee breach in

relation to the yard.


RD 1000

The Natomas basin which is the jurisdiction of Reclamation District No. 1000, is a low-lying

basin surrounded on all four sides by levees. The District operates and maintains miles of canals

and drainage ditches which collect local rainfall from within the Natomas basin and transports


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the water to a system of eight pump stations for discharge into the adjacent river systems. The

major interior canals in the urbanized area (City of Sacramento) in the southern quarter of the

Natomas basin also have a levee system to contain the 100-year flood within the canals. If the

pump stations are not operable due to power failure in the area, the canals are at risk of

overflowing creating localized flooding. Flooding would be shallow (less than 3 feet),

significantly less than from a failure of the perimeter levee; however, it would impact emergency

response and evacuation routes should the perimeter levee system subsequently fail.

Levee Failure

Floods can threaten each reclamation district from several sources. Usually, the possibility of

flooding can be anticipated from eight to twenty hours before the “Emergency Period” is

reached. However, as demonstrated in Linda, California, in February 1986, it is possible for a

levee to collapse with little or no warning when there are still four or more feet of freeboard

available.

Generally, levees fail due to overtopping or collapse. A catastrophic levee failure resulting from

collapse probably will occur very quickly with relatively little warning. Such a failure would

occur where the levee is saturated and the high hydrostatic water pressure on the river side,

coupled with erosion of the levee from high water flows or an inherent defect in the levee, causes

an almost instant collapse of a portion of the levee. Under such circumstances, structures located

relatively near the break will suffer immediate and extensive damage. Several hundred yards

away from the break the energy of the flood waters will be dispersed sufficiently to reduce, but

not eliminate, flooding damage to structures in its path. The flood water will flow in a relatively

shallow path toward any low point in the affected area. Flood water will collect in these low

areas and the levels will rise as the flow continues. When the rivers are high, it is not possible to

close or repair a levee break until the water surface in the river and the flooded area equalize.

A major overtopping of a levee, if flow persists, will result in severe erosion of the levee crowns

on the landward side and cause levee failure over a period of minutes to several hours. A severe

levee overtopping can, therefore, be considered as a levee break for the purpose of determining

the extent of flooding that any area will suffer. Generally, overtopping can be predicted based on

river stages and the warning given depending on the source of the flood waters

RD 341

In addition to the costs incurred to repair or replace the assets destroyed by Sherman Island levee

failure, an immediate cost would be pumping out the Island. To estimate the cost of restoring

Sherman Island, the 2004 failure of the Upper Jones Tract was considered, an Island of 6,259

acres which cost approximately $120 million to restore. This equates to about $19,100 per acre,

and assuming inflation of 4% a year, would be about $22,200 in 2009. Accordingly, it would

cost approximately $221 million to pump out and restore Sherman Island (9,937 acres X $22,200

per/acre). This estimate is conservative in that it does not account for the elevations on the

interior of Sherman Island, which are up to 20 feet below sea level. Sherman will likely


September 2011

impound a greater volume of water per acre than Upper Jones Tract, and per acre restoration

costs will therefore be greater.

Electrical Infrastructure Affected

In addition to the dewatering costs, three major electric transmission lines (greater then 500kV)

cross Sherman Island: the California Oregon Transmission Project, operated by the Western

Area Power Administration, the Pacific Gas and Electric Company (PG&E) Table Mountain-

Tesla line, and the PG&E Vaca-Dixon-Tesla line. These lines work mainly to interconnect

California loads and generation with loads and generation in the Pacific Northwest. The three

lines through the Delta are operated as a coordinated grouping, with maximum imports or

exports limited to provide some joint redundancy to help ensure reliability.

The combined load on these three lines is typically around 4,000 MW, though under some

circumstances it can be as high as 4,800 MW (Mirzadeh 2006). This is approximately ten

percent of statewide summer loads, which is less than the required planning reserve margin of 15

percent. However, other outages may occur at the same time as this disruption, so under some

circumstances the loss of all three lines due to the failure of the Sherman Island levee system

could cause operating problems.

PG&E also operates two other lines with less than 500kV capacity to provide local service to

Sherman Island and nearby Delta Islands. Failure of the Sherman Island levee system would

impact the ability of PG&E to serve the local delta community. The DRMS report estimates the

cost of a two month outage of two 500 kV lines to be $42,000,000.

Oil and Gas Production Affected

Sherman Island has 60 natural gas and oil wells, and approximately 1,082 acres of gas and oil

production fields. In addition, the levees protect 145,514 feet of a natural gas pipeline which

originates in Canada and crosses Sherman Island. Failure of the Sherman Island levee system

would interrupt gas service through the pipeline and gas production and storage occurring on

Sherman Island.

Civil Infrastructure Affected

Sherman Island levees also protect State Highway 160 and the drawbridge at Three Mile Slough.

State Route 160 connects Sherman Island to the mainland Sacramento County on the northeast

corner via Threemile Slough Bridge (Bridge 24-0121), and to Contra Costa County on the

island’s west side, via the Antioch Bridge (Bridge 28-0009). Failure of the Sherman Island levee

system and resulting loss of State Route 160 and access to the Antioch Bridge would severely

impact truck and vehicular traffic relying on this roadway. The Sherman Island Five Year Plan

(2009) estimated that the closure of State Highway 160 would cost approximately $70,000 per

day.


September 2011

RD 800

Potential for severe damage to the Wilton Road crossing over the Cosumnes River would require

detouring of extensive daily high volume traffic of Wilton Road. Closure of the road would

severely delay public safety agency emergency response. Truck and vehicular traffic impacts

would have severe economical impacts to the local economy.

RD 1000

The levees around Natomas were designed to handle the historical “flood of record” which was

the 1907 and 1909 floods on the Sacramento River. Another large flood event occurred in 1937

which the system safely passed with only minor problems. Again, in 1955 an even larger flood

roared through the Central Valley around Christmas. The Natomas levees held with some minor

sloughing along the Sacramento River near the Sacramento/Sutter County line. However, as a

result of this flood, the Army Corps of Engineers raised the Natomas Cross Canal and Pleasant

Grove Creek Canal levees as much as two to three feet in anticipation of future even larger flood

events. In addition, by 1955 Folsom Dam was operational which provided additional flood

storage capacity along the American River on the District’s southern flank.

For the next thirty years, smaller floods came and went without incident until February 1986.

During a 10 day period starting on Valentine’s Day 1986, over 19 inches of rain fell on the

Central Valley resulting in the current “flood of record” on the Sacramento and American River

basins. The District levees were seriously challenged as large areas experienced significant

seepage causing the backside of the levees to erode. Approximately 10,000 feet of levee along

the Sacramento River west of the airport sustained major sloughing. A flood fight was initiated

by the District and eventually the Army Corps of Engineers assumed responsibility. Were it not

for the quick action by the District and the extended efforts by the Corps it is likely a levee

failure would have occurred somewhere along the Sacramento River during that flood.

Following 1986, levee repairs were constructed by the Corps of Engineers to remediate the levee

seepage problem. This work was completed in the early 1990’s. In addition, a joint powers

authority known as the Sacramento Area Flood Control Agency or SAFCA was formed to

develop a comprehensive flood control project for the entire Sacramento area. On New Year’s

day 1997 a flood eerily similar to the 1986 event hit Sacramento cresting at almost the same river

level. Because of the improvements constructed by the Corps several years earlier, the Natomas

levees safely passed this flood with some seepage but little to no levee damage. However, this

flood caused levee failures elsewhere in the Sacramento River system and has awoken a concern

about potential “underseepage” issues and their potential to cause a levee failure in the future. In

addition since these two very large flood events occurred within such a short time frame, experts

now believe we should plan our flood control system and levees for even larger floods;

especially levees protecting urban areas where damages would be extensive and the potential for

loss of life high. This was further engrained in our planning efforts by the flooding in New


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Orleans as the result of Hurricane Katrina in 2006 and the resulting catastrophic damages and

lives lost.

More urbanization is anticipated in Natomas including continued buildout of North Natomas,

more commercial/industrial development associated with Sacramento International Airport, and

even plans for a new large community in the south Sutter County area in the vicinity of Riego

and Sankey Roads. See the previous section for a detailed description of RD 1000 facilities that

would be affected by a flood due to a levee failure in Natomas.


Stream bank erosion is a natural process, but acceleration of this natural process leads to a

disproportionate sediment supply, stream channel instability, land loss, habitat loss and other

adverse effects. As farmers settled the valleys in the 1800s, the Gold Rush drew prospectors to

the hills. As mining in the Sierra Nevada turned to the more “efficient” methods of hydraulic

mining, the use of environmentally destructive high-pressure water jets washed entire

mountainsides into local streams and rivers. As a result, the enormous amounts of silt deposited

in the riverbeds of the Central Valley increased flood risk. As a remedy to these rising riverbeds,

levees were built very close to the river channels to keep water velocity high and thereby scour

away the sediment. However, the design of these narrow channels has been too successful.

While the Gold Rush silt is long gone, the erosive force of the constrained river continues to eat

away at the levee system and stream banks within the districts.

RD 341

Due to the public benefit provided by Sherman Island levees and the valuable local and non-local

assets they protect, District employees conduct visual inspections of the Sherman Island levee

system every day of the year. In addition, the superintendent, Board president and District

engineer survey the levee a minimum of twice a month and participate in an annual inspection of

the levee from the waterside. These inspections are invaluable for identifying issues such as

seepage, cracking, erosion and lack of splash cap and riprap.

According to the District’s Five Year Plan, levee erosion is an ongoing problem. Areas of the

existing levee system most susceptible to failure due to flooding resulting from erosion are those

areas with inadequate riprap protection. The large expanse of waterway of the Sacramento River

adjacent to Sherman Island provides the necessary distance, or fetch, when accompanied by high

winds can produce large waves. The existing rip rap protection lacks the required coverage of

the waterside slope to protect the levee from wind generated waves. The existing large

breakwater quarry stones and limited amount of rip rap are below the high tide level of the

Sacramento River exposing the unprotected levee embankment material to wind generated

erosion damage. High winds originating from the north during periods of high tide and/or high

storm runoff will seriously erode the unprotected levee slope. Accordingly, the District feels that

the lack of riprap slope protection is a critical issue which could affect the stability of the levee,

should erosion damage occur.


September 2011

Figure H.4. Erosion Sites in Reclamation District 341 Levees

Source: RD 341 Five Year Plan (2009)

RD 800

The waterside levee slope of the Cosumnes River is heavily vegetated and considered to be high

value habitat with an abundance of endangered species. Consequently, the vulnerability to

stream bank erosion is high, the cost to mitigate for habitat loss prevents the District from

repairing existing eroded areas.

RD 1000

RD 1000 conducted bank erosion studies in 1999 and 2004 to identify sites where erosion is of

concern and could lead to levee erosion if not addressed. The District has continued to monitor

these sites since 2004. In addition, the Army Corps of Engineers and California Department of

Water Resources undertakes annual inspections of the Sacramento River to identify erosion sites

that could impact the integrity of the adjacent levee system. Four sites both on the Corps list and

the in the District’s reports have now been repaired through contracts with the Corps of

Engineers. These sites are along the Sacrmento River adjacent to Natomas at River Miles 78.0,

77.2, 73.5 and 68.9.

During the winter of 2011, RD 1000 staff undertook emergency repairs at approximate RM 68.4

as high water during this past season eroded a significant portion of the bank and was threatening

the adjacent levee. This site is just downstream of the work done by the Corps of Engineers at


September 2011

RM 68.9 and is part of an approximately 5800 foot reach of eroding bank site identified in the

District’s report that is being monitored.

In addition to this site, the District’s studies in 1999 and 2004 have identified 6 additional small

erosion sites which are being monitored and are being requested to be repaired through the

Sacramento River Bank Protection Project though it currently has not been identified by the

Corps for remedial work.


RD800

According to historical hazard data, severe weather is an annual occurrence in the District.

Damage and disaster declarations related to severe weather have occurred and will continue to

occur in the future. Heavy rain and thunderstorms are the most frequent type of severe weather

occurrence in the area. Wind and lightning often accompany these storms and have caused

damage in the past. Problems associated with the primary effects of severe weather include

flooding, pavement deterioration, washouts, high water crossings, landslide/mudslides, debris

flows, and downed trees. However, it is the secondary effects of heavy rain and storms that are

of concern to RD 800. Heavy rains can cause flooding, levee failure, and stream bank erosion.

Flooding, levee failure, and stream bank erosion can cost RD 800 millions in damages.

H.6 Capability Assessment

Capabilities are the programs and policies currently in use to reduce hazard impacts or that could

be used to implement hazard mitigation activities. This capability assessment is divided into five

sections: regulatory mitigation capabilities, administrative and technical mitigation capabilities,

fiscal mitigation capabilities, mitigation outreach and partnerships, and other mitigation efforts.

H.6.1 Regulatory Mitigation Capabilities

Table H.7 lists regulatory mitigation capabilities, including planning and land management tools,

typically used by local jurisdictions to implement hazard mitigation activities and indicates those

that are in place in the reclamation districts.

Table H.7. District Regulatory Mitigation Capabilities

Regulatory Tool (ordinances, codes, plans)

RD341 RD800 RD1000

Date Comments Y/N Y/N Y/N

General plan N N N

Zoning ordinance N N N

Subdivision ordinance N N N

Growth management ordinance N N N


September 2011

Regulatory Tool (ordinances, codes, plans)

RD341 RD800 RD1000

Date Comments Y/N Y/N Y/N

Floodplain ordinance N N N

Other special purpose ordinance (stormwater, steep slope, wildfire)

Y Y Y RD 800: Encroachment permit regulations RD 1000: Title 23 California Water Code

Building code N N N Version:

BCEGS Rating N N N

Fire department ISO rating N N N Rating:

Erosion or sediment control program Y Y Y RD 800: Erosion control implanted as needed RD 1000: Erosion control measures on levee and canal slopes as necessary

Stormwater management program N N N

Site plan review requirements N N Y RD 1000: Proposed projects which impact levees or drainage facilities require permits from District and include plan review and sign off

Capital improvements plan N N Y RD 1000: District currently developing a CIP

Economic development plan N N N

Local emergency operations plan N N Y RD 1000: Emergency Response Plan as required by State

Community Wildfire Protection Plans N N N

Flood insurance study or other engineering study for streams

N N N

Elevation certificates N N N

Other N


H.6.2 Administrative/Technical Mitigation Capabilities

Table H.8 identifies the District department(s) responsible for activities related to mitigation and

loss prevention in each reclamation district.

Table H.8. District Administrative and Technical Mitigation Capabilities

Personnel Resources

RD341 RD800 RD1000

Department/Position Comments Y/N Y/N Y/N

Planner/Engineer with knowledge of land development/land management practices

Y Y Y RD 800: Consulting engineering firm RD 1000: General Manager is Registered Civil Engineer.


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Personnel Resources

RD341 RD800 RD1000

Department/Position Comments Y/N Y/N Y/N

Engineer/Professional trained in construction practices related to buildings and/or infrastructure

Y Y Y RD 1000: District General Manager

Planner/Engineer/Scientist with an understanding of natural hazards

Y Y Y RD 1000: District General Manager

Personnel skilled in GIS Y Y Y RD 1000: District General Manager

Full time building official N N N

Floodplain Manager N N N

Emergency Manager N N Y RD 1000: District General Manager

Grant writer N N Y RD 1000: Consultant

Other personnel N N N

GIS Data – Hazard areas N N N

GIS Data - Critical facilities N N N

GIS Data – Building footprints N N N

GIS Data – Land use N N Y RD 1000: Consultant Assessment Engineer

GIS Data – Links to Assessor’s data N N Y RD 1000: Consultant Assessment Engineer

Warning Systems/Services (Reverse 9-11, cable override, outdoor warning signals)

N N N

Other


H.6.3 Fiscal Mitigation Capabilities

Table H.9 identifies financial tools or resources that each reclamation district could potentially

use to help fund mitigation activities.

Table H.9. District Fiscal Mitigation Capabilities

Financial Resources

Accessible/Eligible to Use (Y/N)

Comments RD341 RD800 RD1000

Community Development Block Grants

Y Y N RD 800: Usually do not meet cost/benefit requirements

Capital improvements project funding N N Y


September 2011

Financial Resources

Accessible/Eligible to Use (Y/N)

Comments RD341 RD800 RD1000

Authority to levy taxes for specific purposes

Y Y Y RD 800: Requires 2/3 majority vote to increase assessments RD 1000: For increase in assessments must comply with Propositon 218 which requires vote

Fees for water, sewer, gas, or electric services

N N N

Impact fees for new development N N Y RD 1000: District requires impact fee and/or mitigation for new development

Incur debt through general obligation bonds

N N Y RD 1000: District has authority but currently has no GO Bonds outstanding

Incur debt through special tax bonds N N N

Incur debt through private activities N N N

Withhold spending in hazard prone areas

N N N

Other


H.6.4 Mitigation Outreach and Partnerships

RD 341

None at this time.

RD 800

None at this time.

RD 1000

RD 1000 has worked with other partners in the Natomas Basin including the Sacramento Area

Flood Control Agency, Natomas Central Mutual Water Company, Natomas Basin Conservancy,

Sacramento County Airports and the City of Sacramento on projects of mutual benefit that

address public safety and the District’s flood control mission.

H.6.5 Other Mitigation Projects and Efforts

RD 341

The Reclamation District 341 5 Year Plan (2009) lists may mitigation projects and efforts.

These are shown in Figure H.5 and Figure H.6.


September 2011

Figure H.5. Reclamation District 341 Strategy to Meet Desired Levels of Protection



September 2011

Figure H.6. Reclamation District 341 Strategy to Meet Desired Levels of Protection

(cont.)



September 2011

RD 800

Levee maintenance practices designed to protect District levee system includes annual vegetation

management and rodent control. Due to environmental protection limitations, District disaster

reduction practices are limited.

RD 1000

Efforts are currently underway to address both these potential risks with the goal of providing

Natomas at least 200 year level of flood protection (a 0.5% risk of flooding in any given year)

and looking for opportunities to improve the system even beyond this level; particularly as

urbanization of the basin continues.

As described previously, perimeter levee improvements (Natomas Levee Improvement Project)

are currently being constructed by the Sacramento Area Flood Control Agency (SAFCA) with

local assessment funds and State Bond funds. This project will only address a portion of the

perimeter levee issues. The remaining levee improvements are to subsequently be completed by

the Corps of Engineers as federal funds are appropriated

H.7 Mitigation Strategy

This section describes the mitigation strategy process and mitigation action plan for each

reclamation district’s inclusion with the Sacramento County Multi-Hazard Mitigation Plan

update.

H.7.1 Mitigation Goals and Objectives

RD 341 adopts the hazard mitigation goals and objectives developed by the HMPC and

described in Chapter 5 Mitigation Strategy of the base plan.





H.7.2 Mitigation Actions

The planning team for each reclamation district identified and prioritized the following

mitigation actions based on the risk assessment and in accordance with the process outline in

Section 5, Mitigation Strategy, of the base plan. Background information and information on

how each action will be implemented and administered, such as ideas for implementation,

responsible office, potential funding, estimated cost, and timeline are also included. General

processes and information on plan implementation and maintenance of this LHMP by all


September 2011

participating jurisdictions is included in Section 7, Plan Implementation and Maintenance, of the

base plan.

1. RD 341 – Implement the Recommended Actions of the Sherman Island Five Year Plan

Hazards Addressed: Levee failure, flooding, subsidence

Issue/Background Statement: In accordance with the Requirements for the Five Year Plan, the

District has identified projects which have a levee improvement component in addition to a

habitat enhancement or subsidence reversal component (multi-objective projects). The projects

recommended in the Five Year Plan are shown on Figure H.5 and Figure H.6.

Other Alternatives: No action

Existing Planning Mechanisms through which Action will be Implemented: The RD 341

Five Year Plan.

Responsible Office: Engineering

Priority (H, M, L): High

Cost Estimate: Cost estimates for each action are shown on Figure H.5 and Figure H.6.

Benefits (Losses Avoided): Increased life safety and property protection.

Potential Funding: To be determined. The District is assuming that the work described will be

undertaken as a series of Special Projects funded through Project Funding Agreements between

the District and the Delta Suisun Marsh office.

Schedule: Within 5 years

2. RD 800 – Highway 16 Levee Rehabilitation Project

Hazards Addressed: Improve levee adjacent to major highway and two single family

residences.

Issue/Background Statement: Existing reach of levee approximately 1,400 feet in length was

adopted into the District when the District boundaries were expanded. Reach of levee was

constructed by private landowners many years ago, lacks crown width required for levee patrol

or maintenance activities. Existing levee consists mainly of sand and silts, rehabilitation project

would import embankment material, mix with existing levee material to increase levee stability

and integrity.

Other Alternatives: None


September 2011

Existing Planning Mechanisms through which Action will be Implemented: Implemented

through Districts’ Engineer office.

Responsible Office: RD 800

Priority (H, M, L): H

Cost Estimate: Approximately $400,000

Benefits (Losses Avoided): Minimize threat of levee failure at this location; benefit family

residence on land side of levee and State Highway 16 (Jackson Highway).

Potential Funding: Unknown

Schedule: Unknown

3. Reclamation District No. 1000 – Main Drainage Canal Bank Stabilization and Sediment

Removal

Hazards Addressed: Localized Flooding and Protection of Environmental and Recreational

Amenities

Issue/Background: The Natomas Basin which is jurisdictional boundaries for Reclamation

District No. 1000 is surround by a ring levee system protecting the basin and its 100,000

residents, Sacramento International Airport and other commercial/industrial development from

flooding. As a result, all the rainfall that falls within the basin must be collected and pumped

out. Reclamation District No. 1000 is responsible for collecting the stormwater runoff in the

main drainage canals and pumping the runoff over the levee system into the adjacent river. The

Main Drainage Canal is located at the southern end of the basin and conveys stormwater runoff

to Pumping Plants 1A and 1B to be discharged into the Sacramento River. Over time, the canal

has collected sediment from the agricultural and urban runoff which decreases the canal’s

capacity to carry flows. In addition, the flows in the canal have eroded the adjacent bank

creating an unstable situation which impedes access for maintenance and if left unabated will

eventually destabilize the entire bank and adjacent upland area which contains habitat and a City

of Sacramento bike trail.

Reclamation District No. 1000 proposes to mitigate this problem by removing the excess

sediment from the canal bottom to restore its hydraulic capacity and stabilize the adjacent bank

with a combination of toe and slope protection measures.

Other Alternatives: The only alternative to maintain the canal’s hydraulic capacity would be to

enlarge the canal horizontally which would require removal of single family and multi-family

residential structures which is impractical.


September 2011

Existing Planning Mechanism(s) through which Action Will Be Implemented: Reclamation

District No. 1000 would be the lead agency under CEQA and process the required environmental

documents and obtain all necessary permits.

Responsible Office: Reclamation District No. 1000

Cost Estimate: $3.0 million


Benefits (Losses Avoided): Avoid potential flooding of adjacent properties due to insufficient

hydraulic capacity during design flood event; avoid loss of adjacent habitat due to bank collapse;

and avoid loss of recreational amenity (City bike trail)

Potential Funding: City of Sacramento North Natomas Assessment District (for sediment

removal only); Reclamation District No. 1000 Capital Improvement Fund; State grants;

Schedule: Sediment removal to be done in 2012; bank stabilization will be done concurrently if

funding is available; otherwise will follow when funds can be identified.

4. Reclamation District No. 1000 – Security of District Facilities

Hazards Addressed: Localized flooding due to lost pumping capacity

Issue/Background: The Natomas Basin which is jurisdictional boundaries for Reclamation

District No. 1000 is surround by a ring levee system protecting the basin and its 100,000

residents, Sacramento International Airport and other commercial/industrial development from

flooding. As a result, all the rainfall that falls within the basin must be collected and pumped

out. Reclamation District No. 1000 is responsible for collecting the stormwater runoff in the

main drainage canals and pumping the runoff over the levee system into the adjacent river.

In recent years, the District has experienced an increase in theft and vandalism at its pumping

plants primarily related to the copper wiring contained in the plants. When the copper wiring is

cut and/or removed, the plant is inoperable for an extended period. Should the theft correspond

with a major storm event and the pump station be inoperable, the water level will exceed the

capacity of the canal and flood the adjacent urban area.

The project would include installation of security cameras at all the critical District facilities with

the capability to remotely monitor the site and be able to call law enforcement and/or private

security patrols when a break-in has been identified.

Other Alternatives: Alternatives would include full time security patrols which are labor

intensive and do not allow monitoring at several locations simultaneously. A no action plan

would allow the thefts to continue and result in flood damages if they occur during a flood event.


September 2011



documents and obtain all necessary permits.


Cost Estimate: $250,000 initial set up and annual operation and maintenance costs.


Benefits (Losses Avoided): Avoid potential flooding of adjacent properties due to loss of

pumping capacity from theft/vandalism at pumping plants.

Potential Funding: Reclamation District No. 1000 Capital Improvement Fund; State grants;

FEMA mitigation grant funding; Homeland Security

Schedule: District’s security contractor is developing a work scope for implementation in

2012.

5. Reclamation District No. 1000 – Bank and Levee erosion

Hazards Addressed: Levee failure and catastrophic flooding

Issue/Background: The Sacramento River flood control system is continuing to erode

horizontally as the dredged mine tailings have now been flushed down the system. The eroding

river banks have reached critical junctures at some locations and now have begun to erode the

levee system which is protecting the Natomas Basin. If not arrested, the erosion could cause a

failure in the levee and result in the catastrophic flooding of Natomas with over 100,000

residents, Sacramento International Airport and significant commercial/industrial development.

Flood depths would exceed 20 feet in some areas.

In some areas, the erosion has not reached the levee, but if not addressed eventually will which

results in costly bank protection projects with large amounts of rock being placed in the river. It

also results in loss of significant riverine habitat values on the existing banks which are lost over

time as the bank erodes. This erosion can be slowed or in some cases stopped through simpler

more biotechnical projects which are significantly less costly to implement but are not cost

shared by the Corps of Engineers or State of California

The District would propose mitigation projects as these locations of active erosion which have

not reached the critical phase with the less costly alternatives to traditional bank protection

projects to allow the preservation of habitat values along the bank.

Other Alternatives: Alternatives would be to allow the erosion to continue resulting in habitat

losses and do a more costly traditional bank protection project.


September 2011



documents and obtain all necessary permits. Alternatively, the District could approach the State

of California to be the lead agency though they have not been supportive of this alternative

approach in the past.


Cost Estimate: Estimate ranges from $1 million to $5 million depending on the number of

sites.


Benefits (Losses Avoided): Avoid potential levee failure and catastrophic flooding of Natomas

Basin.

Potential Funding: Reclamation District No. 1000 Capital Improvement Fund; State funding;

FEMA mitigation grant funding;

Schedule: Schedule is driven by funding availability. District has no funds in its current budget

for this work, but project implementation could occur in 2012 if outside funding is available.

Annex H: R DISTRICTS - Water Resources

Documents