Little Salado Creek

Project Lead: Stanislaus County

Potential Project Partners:
USACE

Short Project Description:
Construction of a project to partially divert, retain, and percolate up to 1,030 cubic feet per second (cfs) of flow from Little Salado Creek.

Long Project Description:
The County proposes to place the portion of Salado Creek that traverses the 1,532-acre former Crows Landing Air Facility in an underground conveyance. The existing channel conveyance capacity will need to be upgraded to convey the calculated design storm runoff flows. This can be achieved by upsizing the existing underground channel sections and creating new underground conveyances that will replace and exceed the capacity aboveground conveyances. Three segments of the creek would be placed underground:

  • An approximately 4,000 foot segment of the creek that extends northeast from the culvert beneath the Delta Mendota Canal at Davis Road to the culvert on the south side of Runway 11-29;
  • An approximately 1,300-foot segment of the creek that extends from the north side of runway 11-29 to the west side of Runway 16-34; and
  • An approximately 5,800-foot segment of the creek that extends from the east side of runway 16-34 to the existing 24-inch diameter drain pipe at Marshall Road.

The County has considered options that would allow the creek to remain aboveground within its project boundaries, but open channels would not be considered compatible with its plans to reuse airport pavements for the development of a general aviation facility. Federal Aviation Administration (FAA) guidance at Advisory Circular 150/5200-33B, “Wildlife Hazard Attractants on and Near Airports” warn against the creation of open water or wet areas that support wildlife habitat within 10,000 feet of aircraft movement areas. The 1,532-acre site does not provide sufficient area to accommodate FAA’s advised separation. The County does intend to incorporate a groundwater recharge component into the project through the use of perforated pipe in the segments listed above or several other potential methods. The design of the proposed conveyances will be developed following additional hydrological studies.

Unique Project Characteristics:
None specified

Project Status Planning
Project Cost $5,000,000
Project Timeframe 1-5 years
Cost-sharing Stanislaus County, USACE and State for construction; Stanislaus County for maintenance. County may form a Benefit Assessment District for maintenance,; and a local levee district may be formed to operate and maintain flood control portions of the project.
Multi-benefit Project Yes
Types of benefits The project would improve flood risk management and provide groundwater recharge, making it a multi-benefit project.
Source of Project Stanislaus County

Background Information:
The Storm Drainage Water Quality Master Plan was prepared in 2007 for the West Park development provides background information on flows from Little Salado Creek in the project area. The existing study area, consists primarily of agricultural lands and the former Crows Landing Naval Air Facility. The following paragraphs are based or were taken from the 2007 storm drainage master plan.

As illustrated in Figure 2.0, bBoth the Delta-Mendota Canal (DMC) and the California Aqueduct (CAQ) traverse the study area, with the DMC acting as a natural drainage boundary because water cannot flow from one side to the other without being intercepted by the canal. The DMC facility has historically been used for both irrigation and for drainage purposes. The DMC splits the study area roughly down the middle, creating westerly and easterly drainage subareas. The only connection for the two drainage areas is at the Little Salado Creek double box culvert crossing beneath the DMC.

Storm runoff from the Little Salado Creek watershed and west of the CAQ enters the project area from across both Interstate 5 and the CAQ, via two 78-inch diameter pipes, which then open out into a control structure just east of the CAQ. From that point, runoff then enters a 24-inch diameter pipe, which runs east toward the DMC. Just before reaching the DMC, the 24-inch pipe terminates into an open ditch that drains towards and through the double box culverts crossing beneath the DMC. On the east side of the DMC, the box culverts drain out into an open channel ditch that continues in a northeasterly direction toward the low point at the intersection of State Route 33 and Marshall Road. Along the way to this discharge point, it crosses beneath anthe Aairfield through multiple culverts. On the east side of the DMC, Little Salado Creek serves as a tailwater irrigation drain ditch for the surrounding agricultural fields. At its terminus discharge point from the Project site, water drains through a 24-inch diameter drain pipe that flows east along Marshall Road for about 4.5 miles to its final discharge point at the San Joaquin River.

Salado Creek enters the project area at the proposed northwest boundary just north of the intersection of Oak Flat Road and Interstate 5, just south of the proposed stormwater quality detention basin. Storm runoff west of the CAQ crosses over the Aqueduct via an open box culvert overchute and then continues north by means of an open channel until it reaches the DMC. At the DMC, it crosses over the canal via another open box culvert overchute which then drains into an open channel that flows toward the City of Patterson. Also, at the upstream side of the DMC are three recently constructed 60-inch diameter overflow pipes that discharge excess storm runoff directly into the DMC (see photographs below of both overchutes at the CAQ and DMC). From the information gathered thus far, it is not known what flood analysis studies were completed for Salado Creek with these spillover pipes. The limits of this study are outside the scope to evaluate in more detail the impacts of the spill over pipes on Salado Creek. More detailed hydraulic and hydrologic analysis will need to be explored in subsequent reports.