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Cliff Feldheim, Chief
Environmental Planning and Information Branch
Suisun Marsh Program
3500 Industrial Blvd.
West Sacramento, CA 95691
(916) 376-9693
Email:cliff.feldheim@water.ca.gov
Mailing Address:
P.O. Box 942836
Sacramento, CA 94236-0001

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The Suisun Marsh - Physical Facilities constructed by DWR and USBR:

Several facilities have been constructed by DWR and USBR and operate in the Suisun Marsh. These facilities are identified in the Plan of Protection for the Suisun Marsh and the 1987 SMPA. The purpose of these facilities is to provide lower salinity water to managed wetlands. The Initial Facilities, including the Roaring River Distribution System, Morrow Island Distribution System, and Goodyear Slough Outfall, were constructed in 1979 and 1980. The Suisun Marsh Salinity Control Gates were installed and became operational in 1988. Other facilities constructed under the SMPA include the Cygnus Drain and the Lower Joice Island Diversion. The existing facilities are described in detail in this chapter. Several additional large-scale facilities are identified in the Plan of Protection for the Suisun Marsh and the original SMPA, and were to be phased in for salinity control in the Suisun Marsh. However, due to the effectiveness of the Initial Facilities and the SMSCG, and increased outflows, there are no plans to construct additional facilities. More photos of the facilities are available on the Suisun Marsh Facilities Photos page.

Suisun Marsh Salinity Control Gates
(Click on a photo to enlarge)

Top view of gates close-up of gates
Suisun Marsh Salinity Control Gates Close-up of Suisun Marsh Salinity Control Gates (Sep 1987)

© California Department of Water Resources

The Suisun Marsh Salinity Control Gates (SMSCG) were completed and began operating in October 1988. The first year of operation was used to test the gates, and official operation began in November 1989. The facility consists of a boat lock, a series of three radial gates, and flashboards. The SMSCG control salinity by restricting the flow of higher salinity water from Grizzly Bay into Montezuma Slough during incoming tides and retaining lower salinity Sacramento River water from the previous ebb tide. Operation of the SMSCG in this fashion lowers salinity in Suisun Marsh channels and results in a net movement of water from east to west. When Delta outflow is low to moderate and the SMSCG are not operating, net movement of water is from west to east, resulting in higher salinity water in Montezuma Slough. The SMSCG usually begin operating in early October and, depending on salinity conditions, may continue operating through the end of the control season in May.

flashboard removal thumbnail flashboard removal 2 thumbnail
Attaching cables to flashboard Removing flashboard

When the channel water salinity decreases sufficiently below the salinity standards, or at the end of the control season, the flashboards are removed and the SMSCG raised to allow unrestricted movement through Montezuma Slough. Details of annual SMSCG operations can be found in Summary of Salinity Conditions in Suisun Marsh During Water Years 1984–1992 (DWR 1994b), or the Suisun Marsh Monitoring Program Data Summary produced annually by DWR's Environmental Services Office.

Roaring River Distribution System

The Roaring River Distribution System is located near the eastern end of Montezuma Slough. It is designed to tidally pump water from Montezuma Slough to provide for the seasonal water management needs of Suisun Marsh landowners and the Department of Fish and Game on Hammond, Simmons , Wheeler, Dutton, and Van Sickle islands. The system was completed and became operational in 1980.

Fish screens were installed and tested on two intake culverts in 1980 and on the remaining six culverts in 1983. The fish screens at the Roaring River intakes were originally designed for an average approach velocity of 0.5 feet per second. (The design approach velocity is the design flow deivided by the screen area.) An approach velocity of 0.2 feet per second has since been required by the Fish and Wildlife Service for protection of Delta Smelt. During 1997, DWR automated the slide gates on the diversion culverts to throttle diversion flow and maintain 0.2 feet per second screen velocity.

Morrow Island Distribution System (MIDS)
(Click on a photo to enlarge)

MIDS dewatered MIDS Culverts
MIDS Dewatered MIDS Culverts

The Morrow Island Distribution System, in the western Suisun Marsh, was also constructed in 1979 and 1980. The system is composed of two channels known as M-line and C-line. The channels divert water from Goodyear Slough to the easternmost area of Morrow Island. The purpose of the system is to allow wetland managers to fill their ponds with lower salinity water from Goodyear Slough or the Morrow Island Distribution System and drain into Grizzly Bay or Suisun Slough. This reduces the introduction of high-salinity drainage water into Goodyear Slough.

Goodyear Slough Outfall

The Goodyear Slough Outfall was constructed to connect the south end of Goodyear Slough to Suisun Bay. Prior to construction of the Outfall, Goodyear Slough was a dead-end run. The system was designed to increase circulation and reduce salinity in Goodyear Slough and to provide lower salinity water to the wetland managers who flood their ponds with Goodyear Slough water.

Lower Joice Island Unit

The Lower Joice Island Unit consists of two 36-inch diameter intake culverts on Montezuma Slough near Hunter Cut and two 36-inch diameter culverts on Suisun Slough, also near Hunter Cut. Both sets of culverts were called for in the original SMPA and installed in the existing levee in 1991. The facilities include combination gates on the slough side and flap gates on the landward side. The Lower Joice Island facility allows more rapid filling of the site and is connected to the existing distribution system on Individual Ownership Number 424. This facility enables the individual ownership to properly manage its wetlands on Lower Joice Island. Construction of the Lower Joice Island Facility was authorized under SRCD's regional general permit. Under the original SMPA, DWR was responsible for constructing the Lower Joice Island Unit and the individual ownership had the responsibility for operation and maintenance.

Cygnus Unit

The Cygnus Unit includes the installation of a 36-inch drain gate with flashboard riser on Individual Ownership Number 415. Installation of this drain gate was authorized under SRCD's regional general permit and installed in 1991. The individual landowner is responsible for operation and maintenance of this gate.

Cost-Share Facilities

In addition to the facilities mentioned previously, numerous small facilities exist in the Suisun Marsh, many of which were installed or replaced under the DWR and USBR individual cost-share program. The individual ownership cost-share program, as specified in the SMPA, is a program to improve the landowners ability to drain managed wetlands. Under this program, DWR and USBR reimburse 75% the landowners of the cost of replacing culverts (enlarging or lowering) and drain gates, and installing pumps. The individual landowners are responsible for the remaining 25%. The proposed facilities must be specified as "Needed Improvements" in the Individual Ownership Management Plans before being approved for inclusion in this program.