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Mitigation & Conservation Strategy Update
 
 
NATOMAS LEVEE IMPROVEMENT PROGRAM

SUMMARY OF NLIP CONSERVATION STRATEGY & HABITAT MITIGATION ELEMENTS - PHASE 2 PROJECT

Project History

SAFCA’s NLIP entails improving the levee system that protects the 53,000-acre Natomas Basin (Basin) in Northern Sacramento and Southern Sutter Counties, California, including a portion of the City of Sacramento (Exhibit 1-1), to provide the Basin with at least a 100-year level of flood protection. The Basin is generally bounded by leveed reaches of the Natomas Cross Canal (NCC) on the north, the Sacramento River on the west, the American River on the south, and the Pleasant Grove Creek Canal (PGCC) and Natomas East Main Drainage Canal (NEMDC)/Steelhead Creek on the east. The Landside Improvements Project consists of the landside components of the larger NLIP. The Landside Improvements Project includes improvements to correct levee freeboard deficiencies and seepage potential along the NCC south levee, Sacramento River east levee, and the PGCC west levee, and related landscape and irrigation/drainage infrastructure improvements throughout the Natomas Basin.

The Landside Improvements Project consists of several phases of construction, spanning approximately 3 to 4 years, generally between 2009 and 2012. Phase 2 of SAFCA’s NLIP Landside Improvements Project (Phase 2 project), previously described as the 2008 construction phase, will be initiated in 2009 and completed in 2010.

The Phase 2 project consists of: Improvements along the 5.3-mile-long NCC south levee and the Sacramento River east levee from the NCC south levee to 2,000 feet south of the North Drainage Canal (Reaches 1–4B), relocation of the existing Elkhorn Irrigation Canal and construction of the Giant Garter Snake (GGS)/Drainage Canal between the North Drainage Canal and Elkhorn Reservoir (Exhibits 1-5 and 1-6), removal of the culvert under Garden Highway adjacent to the former Reclamation District (RD) 1000 Pumping Plant No. 2 site.

Habitat Conservation

The Natomas Basin provides habitat for a variety of wildlife species, ranging from those that utilize the widely distributed agricultural fields and levee maintenance zones to species that are restricted to remnant patches of native vegetation and the area’s historical agricultural irrigation and drainage ditches and canals. Many common wildlife species utilize the Natomas Levee Improvement Project (NLIP) area, and a number of special-status species also have potential to exist within and adjacent to the levee improvement areas. Special-status species identified to exist in the NLIP project footprint include the following:

  • Valley Elderberry Longhorn Beetle §link§
  • Giant Garter Snake §link§
  • Swainson’s Hawk §link§
  • Burrowing Owl §link§
  • Four Sacramento River Fish Species federally listed as threatened or endangered, two of which are also state listed.
  • Northwestern Pond Turtle 

Three special-status plant species were determined to have potential to exist within the Phase 2 project area and were not identified they include: Rose Mallow, Delta Tule Pea, and Sanford’s Arrowhead.

The Natomas Basin Habitat Conservation Plan (NBHCP) was developed by the City of Sacramento, Sutter County, and the Natomas Basin Conservancy (TNBC) (TNBC website: http://www.natomasbasin.org/) approved by the U.S. Fish and Wildlife Service (USFWS) in 2003 and the California Department of Fish and Game (CDFG) to promote conservation of the NBHCP-covered species in conjunction with economic and urban development in the Natomas Basin. The NBHCP establishes a conservation program designed to minimize and mitigate the expected loss of habitat values and take of “covered species” that could result from up to 17,500 acres of urban development in the Basin.

The NBHCP’s habitat preserve acquisition and management activities are implemented by TNBC, a private, nonprofit organization that began operating in 1998 and who serves as “plan operator” of the NBHCP. TNBC receives mitigation fees paid by developers and other NBHCP participants. These funds are used to acquire, establish, enhance, monitor, and manage habitat preserves in perpetuity. As development occurs within the Natomas Basin, and as TNBC acquires mitigation lands, site-specific management plans are implemented by TNBC to ensure that the objectives of the NBHCP are fulfilled. These management plans include excavation and grading of the acquired lands to create marsh habitats reflective of the floodplain conditions that prevailed in portions of the Natomas Basin before reclamation.

BASIS FOR CONCEPTUAL MITIGATION PLANNING & DESIGN

The NLIP Landside Improvements Project presents a unique, one-time opportunity to reconfigure and protect large nodes of habitat and connective corridors in the Basin at a landscape scale that will help to advance the goals and objectives of the NBHCP and assist the Federal Aviation Administration (FAA), USACE, and the local reclamation districts in achieving their management goals. The project’s conservation strategy, which is described in more detail in the April 2009, Mitigation and Monitoring Plan for SAFCA’s NLIP Landside Improvements Project and Appendices § link § will create, restore, and preserve sensitive habitats in the Basin. This conservation strategy has four primary goals or objectives:

  • Increase the amount of protected habitat and habitat corridors available for NBHCP-covered species.
  • Consolidate large areas of habitat, assisting in the expansion of TNBC reserve blocks in the northwestern and southwestern regions of the Basin.
  • Improve the connectivity between core habitat reserves and other existing natural habitats distributed throughout the Basin, improve linkages between isolated wildlife populations, and substantially increase acreage size of these critical habitats.
  • Meet regulatory compensatory mitigation requirements. A description of each of the mitigation components, including the basis for planning and design for each component, follows.
GIANT GARTER SNAKE DRAINAGE CANAL


BASIS FOR DESIGN

The GGS/Drainage Canal will be a below-grade canal designed to provide habitat for the Giant Garter Snake and local drainage and minor irrigation water conveyance for a portion of the Basin. Water will flow in the canal on the west side of the Basin, in a south to north direction from Elkhorn Reservoir to the North Drainage Canal, and in a north to south direction from Elkhorn Reservoir to the West Drainage Canal. The GGS/Drainage Canal will enhance habitat functionality by permanently linking known Giant Garter Snake population centers and TNBC preserves managed for Giant Garter Snakes in the northern and southern areas of the Basin. This will improve habitat connectivity between the North Drainage Canal and West Drainage Canal and will augment opportunities for movement and genetic diversity of this species throughout the Basin. Irrigation and drainage water currently flowing through the Airport West Ditch will also be incorporated into the GGS/Drainage Canal.

Improved slope grading and a bank vegetation management program designed to optimize habitat quality and eliminate or reduce the frequency of bank disturbance will provide continuous, high-quality shoreline cover and feeding and rearing area for Giant Garter Snake and other semi-aquatic species. Corridors with high-quality managed canal habitat will substantially enhance the viability, resilience, and exchange of Giant Garter Snake populations. The canal has also been designed to reduce the frequency and extent of maintenance disturbance to canal bed and banks, which will benefit the targeted species over the long-term.

HABITAT DESCRIPTION

The GGS/Drainage Canal will generally extend parallel to the Sacramento River east levee. It will extend from the North Drainage Canal near the RD 1000 Pumping Plant No. 2 in the north to the West Drainage Canal in the south by Interstate 5 (I-5). Construction of the GGS/Drainage Canal system will include bank modifications and plantings to improve the habitat quality of the West Drainage Canal from 1-5 to Fisherman’s Lake. The length of the entire GGS/Drainage Canal, including the reconstruction, will be approximately 43,800 linear feet (8.2 miles). The canal north of I-5 will be a major new canal and not a replacement of an existing canal of the same size and extent.

The 11,800-foot segment of the GGS/Drainage Canal that will be constructed during the Phase 2 project is north rth of Reservoir Road the canal will be set back a minimum of 200 feet from the projeof Elkhorn Reservoir and will be parallel to the new Elkhorn Irrigation Canal. § link § North of Reservoir Road the canal will be set back at a minimum of 200 feet from the projected levee toe. The majority of land designated for construction of the GGS/Drainage Canal in the Phase 2 Project is owned by the Sacramento County Airport System (SCAS).

Most existing canals in the Basin have typically steep, horizontal-to-vertical side slopes of 2H:1V to 1H:1V. The GGS/Drainage Canal will be constructed with 3H:1V bank slopes § link§ thus requiring less frequent dredging, bank repair, and bank disturbance. The gentle side slopes will facilitate the shoreline growth of freshwater marsh plants, including native sedges and rushes that will provide habitat for Giant Garter Snake. § link § Upper canal banks will be planted with native perennial grasses to provide better cover for giant garter snake, discourage weeds, raise cutting height above the ground, and reduce the frequency of disturbance to bank vegetation. SAFCA will purchase specialized equipment and vehicles, such as a large hydraulic-arm excavator, to increase the efficiency and ease of canal maintenance and reduce or eliminate the need to drag a bucket, scraper, or V-plow on canal banks. Giant Garter Snake hibernacula (rock piles keyed into the bank), about 50 feet long, will be placed along the canal bank slopes approximately every 300–500 feet.
§ link § Rock piles may extend to the toe of the bank if unstable soils necessitate additional support for the hibernacula.

The GGS/Drainage Canal will be 6–7 feet deep, will have a 10 to 12-foot-wide bottom width, and will have a top bank flush with the ground surface. The GGS/Drainage Canal will have a series of check structures approximately every 2000 feet along its length to maintain consistent water levels in the canal during the snake’s active season (April–October). These water control structures will be planted with the same types of vegetation as the rest of the canal to provide Giant Garter Snakes cover while they pass the structure. Supplemental water will be provided from the surrounding irrigation system. Water depth in the canal is designed to be 4.5 feet ± 6 inches, which will help to minimize tule growth and submerged aquatic weeds in the bottom of the channel. Water will flow at approximately 5 cfs to avoid eutrophication and anaerobic conditions. A maintenance right of way (including a dirt access road) approximately 20 feet wide will be constructed on one side of the canal between the GGS/Drainage Canal and the adjacent Elkhorn Irrigation Canal, and a 10-foot upland native perennial grassland easement (mowed to approximately 6 inches) will be maintained on the other side.


ELKHORN IRRIGATION CANAL


BASIS FOR DESIGN

The new Elkhorn Irrigation Canal will be a “highline canal,” which will flow above grade, confined by flanking earth berms, so that diverted river water can flow by gravity to distribution canals serving agricultural fields. This canal will replace the existing NMCWC irrigation canal, which will be decommissioned during levee improvements. The relocated Elkhorn Irrigation Canal is expected to provide Giant Garter Snake habitat and foraging habitat for Swainson’s Hawk along its banks and right-of-ways. The canal’s design (e.g., gentle side slopes, wider easement area and improved maintenance roads) and modified management of the bank vegetation will reduce the frequency and intensity of bank disturbance and provide some continuous shoreline cover for Giant Garter Snake and other semi-aquatic species. Further, it will facilitate long-term implementation of NCMWC’s existing best management practices (BMPs) designed to improved habitat stewardship. Other secondary functions include water filtration and sediment storage.

HABITAT DESCRIPTION

Most of the new Elkhorn Irrigation Canal will be aligned parallel to Garden Highway, as close to the edge of the levee improvements as possible. In some areas there will be a seepage berm extending from the levee with an overall width of up to 300 - 500 feet. A 50-foot maintenance corridor and a 20-footwide overhead utility corridor will be located between the toe of the new levee’s landside slope and the edge of the relocated canal right-of-way.

Much of the Phase 2 project segment of the new Elkhorn Irrigation Canal falls within lands owned by the SCAS. The canal will have a 10 to 12-foot-wide bottom and 3H:1V slopes.
§ link § The canal will be approximately 6–7 feet deep with a 5 - 6 foot maximum water depth during the irrigation season. The canal is designed to maintain flow demand and existing water delivery levels at various service points.

The gentle side slopes are designed to facilitate the shoreline growth of freshwater plants. Perennial grasses will be planted on the canal banks to provide cover for Giant Garter Snake, discourage weeds, raise cutting height above the ground, and reduce the frequency at which bank vegetation is disturbed. Outer canal banks (dry side of berms) will be seeded and managed as grassland.

The top of the west (levee-side) canal embankment will serve as a patrol road for operators to monitor water levels, adjust water control structures for level control, operate irrigation turnouts, and maintain the canal as needed (i.e., dredge sediment, remove organic debris). The patrol road will be 15 feet wide with a gravel surface. The east (field-side) canal embankment top will also be 15 feet wide to provide access for maintenance equipment (e.g., for dredging and mowing). Access along the east embankment will provide for joint use of the area for flood control in the wet season and irrigation in the dry season.

In addition to the irrigation service and Giant Garter Snake habitat functions described above, the new Elkhorn Irrigation Canal would provide incidental groundwater recharge through the unlined (permeable earth banks and bed) main canal as well as unlined secondary delivery canals served by the main canal.


BOOKFIELD PROPERTY (RICE HABITAT)


BASIS FOR DESIGN

The 353-acre Brookfield property, located in the northeastern part of the Basin, § link § is currently used for rice production and will be used as a borrow site for levee construction. After the borrow material is extracted, the property will be returned to rice production and part of it will be preserved in perpetuity. Rice fields support foraging and rearing habitat for the Giant Garter Snake. By protecting rice fields in the northeast Basin the mitigation plan will create a large area that is managed in perpetuity for Giant Garter Snake, thus contributing to Giant Garter Snake recovery in the Basin. In addition, the preserved rice fields will be cultivated in a manner to maximize habitat suitability and minimize potential for snake injury and mortality, thus improving the habitat quality of the existing rice fields.

Because few surveys for Giant Garter Snakes have been conducted in the northeastern part of the Basin, Giant Garter Snakes have not yet been documented in this portion of the Basin. Nonetheless, Giant Garter Snake is known to occur in suitable habitat throughout the Basin, including areas to the west (e.g., TNBC preserves along the NCC) south (e.g., Snake Alley and nearby TNBC preserves) and east. Therefore, it is likely that Giant Garter Snake will use the rice fields in this portion of the Basin as foraging and rearing habitat.

SAFCA will improve the canal on the south side of the property, improving its connection under State Route (SR) 99/70 to other habitats managed for Giant Garter Snake farther west along the NCC. SAFCA will also improve surface-water irrigation to the site to reduce the site’s dependence on groundwater. In this way SAFCA will contribute to maintaining a balance of the groundwater aquifer, which otherwise could be negatively affected by new cutoff walls to be installed in the levees. A balanced groundwater aquifer would also improve habitat connectivity between rice fields and the existing canal network which are used as movement corridors by the snake.

HABITAT DESCRIPTION

Some of the borrow material for the Phase 2 project will come from the Brookfield property. All of the property used for borrow will be restored to rice production when borrow activities are complete. Half of the acreage used for borrow activities, up to 175 acres (1/2 of 353) will be preserved under a conservation easement (granted to TNBC) restricting land use to rice production. 58.96 acres of the entire 353-acre Brookfield property are also considered USACE jurisdictional irrigated wetlands. These irrigated wetlands are spread fairly uniformly across the 353-acre site. Portions of these irrigated wetlands fall within the area of property to be disturbed, restored, and preserved. Therefore, it is estimated that up to approximately 30 acres of these irrigated wetlands will be preserved for the Phase 2 project.

The Brookfield site is a privately owned property located between Howsley Road and Fifield Road, west of the PGCC west levee in the northeastern part of the Basin. As of summer 2008, the property was in rice cultivation. The rice field is a series of flat patties separated by berms or terraces to maintain constant water surface elevations. Interior berms are 4–5 feet wide and 2–3 feet high. Exterior berms typically include roads along drains, roads separating fields, and roads along irrigation canals. The exterior berm roads are typically 15–20 feet wide and 2–3 feet high.

Rice is typically planted in May and harvested between late August and October, depending on the planting date, rice variety, seasonal growth progress, and rainfall events that may interrupt the harvesting process. The rice is harvested with combines, collected in a storage tank on the combine, transferred to a grain cart, and transferred to a truck.

After rice harvest and drainage of rice fields, rice stubble or straw decomposition is managed with different practices to minimize disease and residue. Several approaches are used:

  • The rice stubble is disked (stubble disk) and subsequently flooded via irrigation.

  • The rice stubble is disked prior to winter rains. No irrigation water is applied.

  • The rice stubble is plowed to bury the residue.

  • The rice stubble is cut, windrowed, baled, and removed from the field with little stubble remaining on the field.
  • The rice stubble is burned in the fall or spring. The amount of burning allowed is limited

The use of fallowing and crop rotation is a function of water availability, disease and pest control, weed control, and the price of rice. Low rice prices occasionally result in a reduction in acreage (fallow). Crop rotations include such crops as wheat, safflower, and corn. Disease control is usually accomplished with the rice stubble management techniques described above. Weed control is accomplished with crop rotations and herbicides. Weed control on the berms varies from allowing the weeds to grow unchecked to maintaining the growth via herbicides. The area devoted to berms is not harvested and weed growth can compromise rice production and crop quality.


MANAGED NATIVE PERENNIAL GRASSLANDS


BASIS FOR DESIGN

To partially mitigate impacts on cropland and grassland suitable for Swainson’s Hawk foraging habitat, SAFCA will create managed native perennial grassland habitats on the new levee slopes, seepage berms, access rights-of way, and canal embankments.. This grassland will be drill-seeded with a mix of native perennial grasses, § link§ and then managed to minimize colonization by ruderal annual grasses and broad-leaved weeds. This grassland will provide moderate-quality Swainson’s Hawk foraging habitat. In addition, grasslands on and adjacent to canal banks will provide basking and aestivation habitat for Giant Garter Snakes.

From a Swainson’s Hawk foraging habitat perspective, the quality of foraging cover is related to the availability of rodent prey. Cover types supporting an available rodent base include native grassland, ruderal grassland, agricultural fields soon after crop harvest and disking, alfalfa and other cut-hay crops, fallow fields, and lightly grazed pasture. Native perennial grasslands may attract larger populations of small mammals than ruderal annual grasslands or some annual croplands. Native perennial grassland cover is available to small mammals year-round. Ruderal annual vegetation has a growth spurt in spring and is typically dry and less palatable by mid-summer. It is also significantly more prone to wildfire and once burned provides little or no habitat. In contrast, perennial grasses grow throughout early spring to late fall, providing a more palatable food source and more cumulative food biomass for small mammals, and are less prone to wildfire. In addition, although rodents may occur in abundance in tall grass or weeds, the height of the vegetation provides them better cover from predators, making the rodents less available to foraging Swainson’s Hawk or other raptors. For prey to be available, vegetative cover must be short (i.e., ideally about 4–12 inches). Mowers will be set to approximately 6" above grade, which is the minimum practical mowing height for the equipment, and the lowest setting to avoid damage to the root crown of bunchgrasses where new growth originates.

Many of the managed grassland sites will connect with adjacent TNBC properties that are managed for Swainson’s Hawk foraging habitat and nesting habitat. Also, much of the managed grassland will be located in close proximity to new woodland nodes and a new woodland corridor created as part of this MMP to provide nesting habitat (see below). New woodlands adjacent to foraging habitat will provide optimal habitat conditions. By connecting these properties, the mitigation project will create a larger contiguous area to be managed for Swainson’s Hawk than currently exists. This will increase the habitat value and functions that these individual properties would otherwise provide in isolation and will contribute to Swainson’s Hawk recovery in the Basin. In addition, grasslands that will be temporarily impacted on existing levee slopes will be enhanced once restored on new levee slopes. Managed native perennial grassland is higher quality foraging habitat than unmanaged ruderal annual grassland found on and next to the existing levee, maintenance roads, and canal systems affected by the NLIP.

HABITAT DESCRIPTION

Managed Grassland in the Flood Control Footprint

The project will expand the existing slopes of the Sacramento River east levee and NCC south levee. Along portions of the Sacramento River east levee, SAFCA will construct 100- or 300-foot-wide earthen seepage berms with a nearly flat slope (50H:1V or less). (In one or more locations, this berm will be up to 500 feet wide.) A 70-foot-wide maintenance and overhead utility access right-of-way will be created parallel to the landside toe of the new levee and seepage berms. Additional setback buffer land will flank some of these features, and property acquisition for the proposed project will leave SAFCA with remnant portions of acquired parcels that are not essential to flood control uses. With the exception of the crown of the levee, managed native perennial grassland will be created in these areas and on levee/berm surfaces. § link § These grasslands will be mowed to approximately 6–12 inches.

Most of the property within the Phase 2 Project’s flood control footprint will be acquired or placed under permanent easement by SAFCA as part of the project. The Phase 2 areas are located primarily in Sutter County within the Basin, with a smaller proportion (i.e., the flood control footprint along Reaches 4A and 4B of the Sacramento River east levee) in Sacramento County northwest and west of the Sacramento city limits. Phase 2 lands are currently a combination of un-irrigated grassland, field crops, rice, canals, and woodlands. The surrounding area is rural and consists primarily of agricultural lands and TNBC reserves, with a few scattered residences.

Managed Grassland on Canal Embankments

Adjacent to the newly constructed GGS/Drainage Canal and new Elkhorn Irrigation Canal will be embankments and access rights-of-way on which native perennial grasslands will be established. Many of these grasslands will be mowed to approximately 6–12 inches (which is consistent with standard Reclamation District 100 maintenance practices); however, the grasslands directly adjacent to the canals may be maintained at a taller height to provide cover and to avoid damage to Giant Garter Snakes. § link §

Most of the property within the Phase 2 Project’s canal alignments is currently owned primarily by the SCAS. These areas are located in Sacramento County northwest and west of the Sacramento city limits. These lands are currently a combination of un-irrigated grassland, field crops, rice, canals, and woodlands. The surrounding area is rural and consists primarily of agricultural lands, with a few scattered residences.


AGRICULTURAL UPLAND SWAINSON'S HAWK FORAGING HABITAT


BASIS FOR DESIGN

To reduce impacts to Swainson’s Hawk foraging habitat, SAFCA will create, enhance, and preserve in perpetuity Agricultural Upland Swainson’s Hawk Foraging Habitats. Biologists have determined that Swainson’s Hawk prefer agricultural habitats with cultivation activities that attract prey such as voles and other small mammals and harvest activities that expose them to aerial predation. The multiphase NLIP Landside Improvements Project will result in the creation or preservation of many more total acres of foraging habitat than the total acres of foraging habitat affected by the project. This is because much of the affected acreage is higher-value cropland, while most of the mitigation acreage will be moderate-value managed native perennial grassland established within the flood control footprint (levee slopes and operations and maintenance corridors). The project will include approximately 150 acres of cropland outside the project footprint that will be managed to provide high-quality foraging values. The types of crops produced on these lands will be defined in a site-specific management plan prepared for each mitigation site, and may include rotations and varying management regimes of hay clovers and other crop species suitable to the site conditions. The management plan will include required management criteria to maximize foraging habitat value for Swainson’s Hawk. Criteria used to define suitable crop types for each mitigation site will be consistent with research described in Estep 1989, Estep 2008, and Woodbridge 1998.

Approximately 90 cropland acres have been identified at the Novak and Lauppe properties and the remaining acreage (60 acres) will be identified as part of the Phase 3 and Phase 4 projects. Like the grasslands described above, in order to maximize the value of preserved foraging crops, mitigation locations were selected and are being purchased to connect with or be in close proximity of TNBC properties that are managed for Swainson’s Hawk foraging habitat and nesting habitat, and new landside woodlands that will be created as part of this MMP to provide nesting habitat. By connecting these properties, the mitigation project will create a larger contiguous area managed for Swainson’s Hawk than currently exists. This will increase the habitat value and functions that these individual properties would otherwise provide in isolation and will contribute to Swainson’s Hawk recovery in the Basin.

HABITAT DESCRIPTION

Two properties have been identified for forage crop creation, enhancement, and preservation: the Lauppe property and the Lauppe property is located along Reach 2 of the Sacramento River east levee, in the northwest area of the Basin. It is surrounded by agricultural lands and the Sacramento River. This 20.6-acre property is used to produce field crops, including rotations of alfalfa and other high-value foraging crops. A house and associated outbuildings are located on about 3.5 acres of the property. The house and outbuildings will be removed from the property, and most of these 3.5 acres plus an additional 3 acres of cropland will be used to create the adjacent levee and woodland corridor. The remaining 14 acres will be enhanced by farming field crops that provide high-quality forage habitat, including rotations of alfalfa crops. All 14 acres of Agricultural Upland Swainson’s Hawk Foraging Habitat will be preserved in perpetuity.

The Novak property is located along Reach 12A of the Sacramento River east levee, in the southwest area of the Basin. This property is surrounded by agricultural lands and the Sacramento River. The 94-acre property includes approximately 33 acres of orchards, and approximately 61 acres of cropland, which were fallow in 2007. The orchards and crops will be removed as part of the project so that the site can be used for borrow material and for construction of the new Riverside Canal during a future phase. Following borrow and construction activities, the remaining 76 acres of land will be enhanced by farming field crops that provide high-quality foraging habitat, including rotations of alfalfa. These 76 acres of Agricultural Upland Swainson’s Hawk Foraging Habitat will be preserved in perpetuity as mitigation.


LANDSIDE WOODLANDS


BASIS FOR DESIGN

To mitigate the loss of woodlands SAFCA will acquire cropland and ruderal grassland properties, establish woodlands on this land, preserve these properties in perpetuity, and preserve additional landside Valley Oak Woodland already in existence.

Two types of landside woodlands will be created: a 100–200 foot wide corridor of woodlands running generally north-south along the east side of the new levees, and larger nodes of woodland groves created contiguous to the linear corridor as well as adjacent to existing high quality Valley Oak Woodlands. § link § Trees provide nesting habitat for Swainson’s Hawk and enhance the value of foraging habitat (i.e., new woodland + foraging land = optimal habitat). Large areas within the Basin have few or no mature trees or recruitment of saplings, so additional trees could increase long term habitat values for Swainson’s Hawk. Increasing landside woodlands in the Basin is expected to bring new nesting opportunities to areas farther inland from the levees where those habitat values have been lost, and to make existing Swainson’s Hawk foraging habitat on interior agricultural fields more accessible. This will increase the productivity of these lands as foraging habitat.

The priority for woodland corridors is for tall, fast-growing tree species to be planted adjacent to Swainson’s Hawk foraging fields to increase potential nest sites for Swainson’s Hawk and other bird species, to maximize habitat-edge transitions between nesting and foraging habitat, and to minimize distances between nesting and foraging areas.

New woodland corridors will be wider than most of the existing tree rows, and more contiguous than other landside woodlands that are scattered throughout the Basin in small groves or narrow tree rows along the edges of fields, canals, and roads. Establishing the woodland corridors will substantially increase the acreage and spatial distribution of landside woodlands adjacent to surrounding protected and managed native perennial grasslands, cropland, and wetlands. This, in turn, will provide an important opportunity to diversify the complexity of the landscape and increase beneficial habitat edge effects. Where possible landside woodland corridors will be established along levee reaches where there are gaps in the riverside forest community. This will increase the interface of landside woodlands connected to the riverside riparian forest and will enhance daily and seasonal movement corridors for wildlife and avian populations between habitat types, and between foraging and breeding areas.

The woodland groves will provide superior refuge, habitat diversity, and cover for many wildlife species. These woodland groves will also promote successful nesting by a variety of native birds deeper within the grove canopy, where nest parasitism by crows, cowbirds, and starlings is less of a factor in breeding success. The establishment of larger woodland groves will likely also attract Oak Woodland bird species, such as Oak Titmouse, Acorn and Nutall’s Woodpecker, Western Scrub-Jay, and Raptor Species.

The sites will provide connectivity between adjacent TNBC properties that are managed for Swainson’s Hawk habitat. By connecting these properties, the project will create a larger contiguous area managed for Swainson’s Hawk than currently exists. This will increase the habitat value and functions that these individual properties would otherwise provide in isolation, and will contribute to Swainson’s Hawk recovery in the Basin.

HABITAT DESCRIPTION

These landside woodlands will consist of a mixture of native oak woodland and riparian species, including Elderberry shrubs, but the dominant tree species will be Valley Oak, Sycamore, and Cottonwood § link §

Cummings North Property

The Cummings North property, § link § is adjacent to the Sacramento River east levee in Reach 1, will be enhanced and preserved in perpetuity. The surrounding area is rural and consists primarily of agricultural lands and TNBC reserves, with a few scattered residences. This 22-acre property contains some mature oak woodland and ruderal grassland adjacent to cropland. Existing ruderal annual grassland in the interior of the surrounding woodland will be converted to native perennial grassland, with tree, shrub and elderberry clusters planted within the meadow. In addition, the woodland perimeter will be expanded to maximize habitat-edge transitions between nesting and foraging habitat.

Lausevic Property

The Lausevic property, which is east of the Sacramento River east levee in Reach 2, has also been acquired by SAFCA, and will be enhanced and preserved in perpetuity. This 23-acre property is adjacent to the Sacramento River on the west and the largely abandoned Rio Ramaza residential subdivision on the east. § link § The Rio Ramaza subdivision contains some scattered woodland groves, but consists mostly of ruderal grasslands and scattered houses and roadways. The Lausevic property and the Rio Ramaza subdivision are surrounded by cropland and by TNBC preserves containing woodlands, grasslands, and agricultural crops.

The Lausevic property contains some high quality woodland groves, including a large valley oak woodland, but consists mostly of ruderal grasslands. Woodland groves, elderberry clusters, and native perennial grassland will be created on the portions of the property that consist of ruderal grassland. Woodland plantings will be contiguous with existing mature oak and riparian woodlands both within and bordering the Lausevic parcel boundaries. Existing woodlands will also be preserved in perpetuity.

Woodland Corridor

Woodland corridors will be created along Reaches 1–4A adjacent to the Sacramento River east levee. The woodland corridors will be created on the east side of the levee access rights-of-way, immediately adjacent to agricultural fields, and contiguous with new and existing woodland nodes. Most of the corridors will be approximately 100–200 feet wide, but they will be substantially wider in some areas. The corridors will be several hundred to a few thousand feet long, depending on location and land use constraints, and they will not extend into the Airport RPZ (Runway Protection Zone). § link §

The woodland corridors will be created on property that will be acquired by SAFCA as a part of the project. The woodland corridors are located in relatively flat agricultural areas. The Alluvial soils bordering the Sacramento River are mostly loams found along historic high-flow overbank channels where river alluvium deposited. These soils include sandy loam and silt loam, ranging from 0% to 2% slopes. These particular soil types such as the Columbia loams flanking the river represent the location of historical riparian forest and oak woodland, and are ideal for the growth and long-term viability of created woodland corridors. The surrounding area is rural and consists primarily of agricultural lands, fallow ruderal fields, and TNBC reserves, with a few scattered residences.

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