«SONOMA COUNTY AGRICULTURAL COMMISSIONER’S OFFICE TABLE OF CONTENTS INTRODUCTION REGULATORY REQUIREMENTS CALIFORNIA TIGER SALAMANDER MAP CHAPTER ONE ...»
Best Management Practices for
Agricultural Erosion and Sediment Control
SONOMA COUNTY AGRICULTURAL COMMISSIONER’S OFFICE
TABLE OF CONTENTS
CALIFORNIA TIGER SALAMANDER MAP
LAYOUT AND SITE DEVELOPMENT
BEST MANAGEMENT PRACTICES
EXAMPLE VINEYARD LAYOUT
EXAMPLE VINEYARD LAYOUT NEAR STREAM
BEST MANAGEMENT PRACTICES FOR AGRICULTURAL ROADS
EXAMPLE OUTSLOPED ROAD
EXAMPLE INSLOPED ROAD
CHAPTER THREECOVER CROPS, TILLAGE PRACTICES AND EROSION CONTROL
BEST MANAGEMENT PRACTICES
EXAMPLE 3.1 COVER CROP SEED MIX
EXAMPLE 3.2 TRACKING IN STRAW MULCH
EXAMPLE 3.3 STRAW BALE SEDIMENT BARRIER
EXAMPLE 3.4 STRAW WATTLE INSTALLATION
BEST MANAGEMENT PRACTICES
EXAMPLE 4.1-STORM DRAIN OUTFALL MODIFICATION
EXAMPLE 4.2-STORM DRAIN OUTFALL MODIFICATION AT TOP OF STREAM BANK
EXAMPLE 4.3 VINEYARD INLET WITH SEDIMENT TRAP
EXAMPLE 4.4CONCRETE INLET WITH SEDIMENT TRAP
EXAMPLE 4.5 ROCK OUTLET FOR STORM DRAINS
EXAMPLE 4.6 ROCK OUTLET FOR SWALES
EXAMPLE SEDIMENT BASIN
EXAMPLE AG ROAD WATER BAR
EXAMPLE TEMPORARY DRAINAGE SWALE
CHAPTER FIVERIPARIAN ZONES
BEST MANAGEMENT PRACTICES
REQUIRED STREAM SETBACKS
LEVEL I PROJECTS AND ALL REPLANTS
LEVEL II PROJECTS
EXAMPLE VINEYARD SETBACK/FILTER STRIP
REQUIRED WETLAND AND POND SETBACKS
CHAPTER SIX TREE REMOVAL AND EROSION CONTROL
BEST MANAGEMENT PRACTICES
MONITORING AND REPORTING
APPENDIX POTENTIALLY COHESIONLESS SOILS MAP
POTENTIALLY COHESIONLESS SOILS MAP UNITS
SOIL LOSS RATIO (PERMANENT AND TEMPORARY BMPS)
LENGTH OF SLOPE (LS) VALUES
On December 9, 2008, the Sonoma County Board of Supervisors adopted Ordinance No. 5819, amending the Sonoma County Code and the previously adopted 2007 California Building Code with respect to the regulation of grading, drainage, and vineyard and orchard site development.
One of the requirements of this ordinance is compliance with best management practice guidelines. The minimum requirements discussed in this handbook are specific to agricultural practices in Sonoma County for Sonoma County soul types and weather conditions.
The purpose of the Sonoma County Best Management Practices handbook is to provide the minimum requirements to control water quality impacts from accelerated erosion due to agricultural activities in Sonoma County. The intent of this handbook is to show what basic practices are effective in reducing erosion and sedimentation and to show how to install these practices.
It is not the intent of this handbook to provide design criteria for engineered structures. Steeper slopes and projects with grading and drainage components may need structures designed by a licensed engineer.
The process of soil erosion by water involves the detachment of particles from the soil mass, the transportation of the particles by runoff, and the eventual deposition of particles in the form of sediment. Most of the energy responsible for erosion is provided by the impact force of falling raindrops or by the force of surface storm water runoff. Disturbance of soil from farming practices can add to the problem by loosening and pulverizing soil particles, thereby making them more easily moved by rainfall and runoff and by removing the vegetative cover that protects and holds together soil and slows runoff velocity thereby decreasing its capability of transporting soil particles downslope.
Raindrops strike the ground with a velocity of approximately 20 mph. The force of the raindrops breaks apart soil particles, and surface runoff transports the particles downslope. If the soil is not protected from the force of raindrops it will be lost from the agricultural operation and eventually it will be deposited as silt in a creek or waterway where it can have water quality impacts and harm fish habitat.
Drainage features such as pipe with inlets, water bars, swales, and perforated pipe can discharge sufficient water to create a gully, sediment plume, or both, that can extend to a stream channel.
These structures are very effective in some situations, provided they have a sediment collection component.
Technical support was provided by Munselle Civil Engineering and Enterra Associates.
Front cover photographs are (clockwise starting from upper left): Rock lined channel designed by Atterbury & Associates, Inc., olive orchard at Kunde Winery, sediment basin designed by Atterbury & Associates, Inc., and erosion control featuring cover crop, straw mulch, and straw wattles designed by Edwards Engineering.
Development of agricultural land for new crop planting or replanting may require permits from various regulatory agencies. The following are some guidelines to help determine if permits would be required and the agencies to contact.
Planting New Vineyard/Orchard or Replanting Existing Vineyard/Orchard If your project is to plant new vineyard/orchard or replant existing vineyard/orchard, you will need to contact and obtain a permit from the !gricultural ommissioner’s Office (707-565-2371).
Oak trees are protected in certain areas of the county. heck with the !gricultural ommissioner’s Office or Permit and Resource Management Department (707-565-1900) to see if a permit is needed. Redwood, fir, and pine trees may not be removed without first contacting the California Department of Forestry (707-963-3601).
Grading and Drainage
If your project involves moving more than 50 cubic yards of soil or stockpiling more than 50 cubic yards of material, you may need a grading permit from the !gricultural ommissioner’s Office (707Also, if you are placing fill in the Laguna de Santa Rosa or within the Flood Prone Urban Area (see maps at PRMD) you may need a grading permit. In order to obtain a grading permit you may need to submit engineered plans.
If you are altering surface flow runoff by adding or changing existing drainage swales or installing drainpipe with inlets, you may need drainage review from the !gricultural ommissioner’s Office.
This review may require you to submit an engineered drainage plan. Re-directing subsurface flow with perforated pipe or french drains may not require drainage review. You must not discharge the pipe directly into a creek or onto a creek bank. Make sure the discharge end of the pipe is protected with rock rip-rap.
Altering a Creek or Stream Bed
A creek or stream is defined by the Department of Fish and Game (CDFG) as any drainage way having a defined bed and bank. These features may be under the jurisdiction of the CDFG. You may not substantially alter or obstruct a creek or stream or its bank subject to state jurisdiction without first obtaining a Streambed Alteration Agreement from the CDFG (707-944-5500). Activities which may require this prior approval include the diversion of a stream or creek, construction of a discharge pipe within a creek or stream, depositing or disposing of debris, waste, or other material containing crumbled, flaked, or ground pavement where it may pass into a creek or stream, the placement of a culvert into a creek or stream or construction of a stream or creek crossing.
Wetlands and Vernal Pools
Areas that are seasonally or perennially saturated with water can represent unique aquatic plant habitat such as wetland and vernal pools. Many of these areas are habitat for endangered species of both plants and animals. A common misconception is that these areas are springs and can be drained with the addition of subsurface drainage. Wet areas may be jurisdictional waters of the United States and may be regulated by the State of California. Their development for an agricultural crop may require a permit from the United States Army Corp of Engineers (415-977-8439) and/or
Endangered Species Both Federal Endangered Species Act (FESA) and the California Endangered Species Act (CESA) prohibit the “take” of a protected wildlife species. Under S!, “take” includes activities that kill or injure a listed species, or activities that result in habitat impacts that cause actual death or injury.
Under S!, “take” means to "hunt, pursue, catch, capture, or kill, or attempt to hunt, pursue, catch, capture, or kill" a listed species.
California Tiger Salamander: On July 22, 2002, the United States Fish and Wildlife Service listed the Sonoma population of the California tiger salamander (CTS) as endangered under the FESA. On July 20, 2010, the State of alifornia listed the TS as “threatened” under the S!. TS require vernal pools and other temporary bodies of water for breeding and upland habitat (including ground squirrel holes) for growth and survival. CTS migrate between upland and aquatic areas during the fall months. CTS are known to exist in distinct areas of Sonoma County. If you are uncertain whether CTS may exist on your property we encourage you to consult with a qualified biologist.
Other Protected Species: Certain other plant and animal species present in Sonoma County are listed species under the FESA and CESA. If you are uncertain whether any protected species may exist on your property, we encourage you to consult with a qualified biologist.
If your proposed project involves activities that might “take” any listed species under alifornia or federal law, you will need to consult an expert as to your obligations under the FESA and CESA or contact the United States Fish and Wildlife Service (USFWS) (916-414-6600) and/or the California Department of Fish and Game (707-944-5500) directly to discuss your project and its potential impacts. If your proposed project involves activities that might “take” any listed species and also requires a federal permit, such as a permit from the United States Army Corp of Engineers as described above or relies on federal funding, consultation with USFWS will be required
iiiivCHAPTER ONE-Layout/Site Development
The layout of a vineyard/orchard can substantially affect the quantity of runoff delivered to a stream. Vineyards/orchards should be planned to take advantage of natural drainage features and maximize infiltration. Steps should be taken to minimize impacts on stream flow. Select varieties of grapes that are appropriate for the soil type, water source and frost conditions.
Environmental Concerns Steep slopes are more vulnerable to erosion compared to gentle slopes. When fine sediments are eroded from adjacent hillsides, they can settle within the stream channel, fill in pools necessary for rearing, and smother gravels needed for spawning.
Riparian areas provide stability to the natural drainage features of the land and are an important habitat component of streams. Trees provide shade that keeps water cool. Increased peak flows in a stream increase the likelihood that juvenile salmonids will be flushed downstream away from their rearing habitats. Reduced aquifer recharge reduces summer low flows and may result in a dewatering of streams and salmonid death Site Evaluation Examine the property for any signs of instability. Identify soil types, slopes, and types of vegetation, water source, frost prone areas, ponds, wetlands, designated and undesignated streams and riparian zones. Inventory existing roads and drainage improvements. To inform the landowner of site specific biotic resources, have a qualified expert conduct an assessment or studies for potential impacts to any listed species under California or federal law.
Best Management Practices
1.1. In accordance with the ounty’s rading, rainage, Vineyard/Orchard Site evelopment ordinance, for new vineyards/orchards or replanted vineyards/orchards on steep slopes or highly erodible soils, follow plans prepared by a qualified civil engineer.
1.2. Avoid disturbing any areas with landslides, gullies and slips.
1.3. Reduce the length of slopes draining to riparian areas using numerous drop inlets with sediment traps, vegetated filter strips, or rolling dips.
1.4. Incorporate structural erosion control systems to intercept and diffuse water flow and encourage infiltration into vineyard design: Use drop inlets with sediment traps; daylight underground outlets to vegetated swales; energy dissipaters; infiltration galleries; or sediment basins to prevent excess sediment from entering streams.
1.5. Plan vineyard/orchard blocks and developed areas supporting the vineyard/orchard to drain to a grassy filter area or a detention/sedimentation pond to remove pollutants.
1.6. Riparian areas should be avoided if still intact, and if altered, they should be re-vegetated and restored (see Chapter 5 for more details).
1.7. Consolidate all-weather surfaced access roads, staging areas, and parking away from the riparian zone.
1 1.8. Consider the most efficient use of the water for irrigation and frost protection. Avoid planting in frost prone areas (e.g. near trees or buildings) that would require a water source for frost protection. Consider planting in frost prone areas if the area can be protected by wind machines.
1.9. Avoid planting early budding varieties in frost prone areas that would require sprinkler frost protection (e.g., areas where cold air is trapped by natural topography or vegetation).