«SONOMA COUNTY AGRICULTURAL COMMISSIONER’S OFFICE TABLE OF CONTENTS INTRODUCTION REGULATORY REQUIREMENTS CALIFORNIA TIGER SALAMANDER MAP CHAPTER ONE ...»
1.10. When planning a new vineyard or a replant, consider dry farming once vines mature and groundwater conditions within the root zone are favorable.
1.11. Ensure that you have a legal right to your water source.
1.12. Base layout and site development on a qualified expert’s recommendations with respect to any listed species protected under California or federal law. Avoid any action that constitutes take under the Federal Endangered Species Act or California Endangered Species Act, unless accompanied by an Incidental Take Statement or Incidental Take Permit issued by the appropriate agency.
Figure 1.1 Example Vineyard Layout 2 Figure 1.
2 Example Vineyard Layout Near Stream 3 CHAPTER TWO-Roads Fine sediments eroding from roads are a major source of sediment to streams in Sonoma County and throughout Northern California. Whether it is surface runoff or concentrated storm runoff, sediment and other pollutants are reaching streams and harming our natural resources.
Good planning, proper location and the use of progressive construction practices result in low maintenance, low impact roads.
Removing existing access roads from within the riparian zone will reduce fine sediment inputs, greatly improving spawning and rearing habitats for salmonids and eliminate the influence of the road on the stream system.
Environmental Concerns Fine sediment delivered from roads to streams reduces the flow of oxygenated water to embryos, limits invertebrate prey, fills in pools used for rearing, and cements spawning gravels, reducing the area available for adult salmonids to successfully spawn.
If roads are built too close to a stream, the result is often that streams are armored and straightened to protect the adjacent road. Simplified channels provide less cover and rearing habitat for salmonids. Furthermore, roads interrupt the functions of riparian zones in providing bank stability, filtering sediment and pollutants, and providing shade, large woody debris, and invertebrates to streams. Improperly sized or designed culverts are a common barrier to fish passage in Northern California stream systems.
Site Evaluation Use a map or aerial photo to view the location of the road system, including abandoned and unused roads and identify all potential sources of sediment to the stream. Identify stream crossings and the type and size of culverts. Examine the downstream side of stream crossings to see if there is erosion from concentrating flows or by directing flows into the streambank.
Best Management Practices for Agricultural Roads
2.1. Decommission or relocate existing roads away from the riparian zone whenever possible.
2.2. Weatherproof or harden daily traffic roads. Pave or chip seal before the rainy season to allow toxic compounds in the oils to solidify, degrade or volatilize from the road surface and not be delivered to waterways.
2.3. Establish a thick cover crop on temporary or seasonal ranch roads by October 15. Depending on traffic, this may require active seeding annually.
2.4. Use straw mulch during the rainy season in places where cover crops are sparse. Monitor and augment straw treatments as necessary.
4 2.5. Blade existing roads in dry weather when possible, but while moisture is still present in soil and aggregate to minimize dust and maximize compaction to prevent road fines from being discharged from the road surface.
2.6. Do not sidecast the bladed material to areas where the material can enter the stream directly or indirectly as sediment. Sidecast material can indirectly enter the stream when placed in a position where rain or road runoff can later deliver it to a channel that connects with the stream.
2.7. Out-slope roads wherever possible to prevent the concentration of flow within the ditch, to promote even draining of the road surface and to minimize disruption of the natural sheet flow pattern off the hill slope to the stream.
2.8. If unable to eliminate in-board ditches, crowning the road can remove half the road surface drainage from the ditch.
2.9. Use water bars and rolling dips to break-up slope length, diverting water to well-vegetated areas.
2.10. Maintain in-board ditches and line them, if needed, with geotextile fabric or rock.
2.11. Remove stream crossings wherever possible.
2.12. Replace culverts, fords, or Humboldt crossings with single span bridges where possible
2.13. Ensure that all stream crossings meet National Marine Fisheries Service and California Department of Fish & Game guidelines for fish passage.
2.14. Design culverts to pass 100-year flow.
2.15. Check culverts periodically during the rainy season to ensure that they are not plugged with debris.
2.16. Minimize erosion downstream of culverts by using energy dissipaters.
2.17. Monitor energy dissipaters to make sure that they do not wash away or shift.
2.18. Maintain culverts at the level and gradient of the stream bed. In non-fish bearing streams, with “shotgun” culverts, use pipe extenders (e.g., elephant trunks) to bring the discharge down to the level and gradient of the stream.
5 Figure 2.1 Example Outsloped Road Figure 2.1 Example Insloped Road 6 CHAPTER THREE-Cover Crops/Tillage Practices Planting cover crops is the most cost effective method to reduce the introduction of sediment, nutrients, and pesticides to the stream channel through overland flow.
In addition to their ability to prevent sheet erosion, cover crops can serve many agronomic purposes such as improving tilth, fixing nitrogen in the soil, and providing habitat for beneficial insects.
Protecting bare soil surfaces is one of the best ways to prevent soil loss. Grasses, depending on the type, provide short-term soil stabilization for disturbed areas during construction of your project and can serve as long-term permanent soil stabilization for disturbed areas. There are many different seed mixtures you can choose from. Here are some key things to
consider when choosing and planting a cover crop:
• Most important, be sure that your seed mixture provides overstory (tall fast growing plants like rye, grass, or barley) and understory (low growing broadleaf plants like clover) protection.
For example, a mixture of oats and barley will only provide overstory protection and will only be slightly more effective than if you did nothing. The raindrops can still fall down between the tall plant stalks and dislodge soil particles. If you mix in some clover and brando brome, you will get understory protection and the soil will have better protection.
• The amount of seed you will need depends on the mix you choose. It can range from 30 lbs per acre for a more permanent type of cover crop to 90 lbs per acre for a quick erosion control soil builder mix. Your seed company will be able to help you determine what mix is best for your project and give you the recommended seed rate.
• Broadcast your seed in the fall. In order to have adequate protection by the start of the rainy season (October 15), the seed should be planted by mid-September. Initial irrigation will be required for most grasses with follow-up irrigation and fertilization. The cover crop should look like a lawn by October 15 (for new plantings and November 15 for replants) in order to provide adequate protection for the soil during the first heavy rains. If you cannot plant by mid-September and irrigate the seed, then you may plant your seed in October and cover it with straw mulch applied at the rate of two tons per acre.
Environmental Concerns Surface runoff can carry sediment, nutrients, and pesticides directly to a stream, where they affect salmonids and their habitat.
7 Site Evaluation Inventory all areas that have rilling and eroded channels. Also, note areas that have sparse natural vegetation or areas where the cover crop has not taken. These areas may need some soil amendments or may need to be reseeded with a different seed mix
3.1. Establish thick cover crops by October 15 and maintain them throughout the rainy season (until April 1st).
3.2. Use straw mulch (2 tons/acre) in areas where cover crops are planted late in the fall or if rain is likely after the cover crop has been tilled and there is no perimeter erosion control.
3.3. Whenever possible, avoid tilling early in the spring or late in the fall. Leave filter strip areas or other perimeter erosion control in place if the vineyard rows are tilled early.
3.4. Minimize tillage practices, especially if slopes are greater than nominal (5-10%) or if soils are highly erodible.
3.5. Filter strip areas or other perimeter erosion control should be left in place if the vineyard/orchard rows are tilled early.
3.6. Do not till turn-around areas except for the infrequent need to reduce compaction. In this case, promptly cover the soil with straw and replant with a cover crop before the rainy season.
3.7. If you till regularly, use sedimentation basins or vegetated filter strips to filter sediment before it reaches the stream.
3.8. Avoid bringing equipment into the vineyard/orchard during the wet season. Close seasonal roads to traffic and maintain permanent roads to prevent erosion.
3.9. Keep on site extra erosion control materials such as straw bales or wattles, gravel or geo-textile fabric and train vineyard crews in their proper installation.
3.10. Check the site after each rainfall event Example 3.1 Cover Crop Seed Mixes 8 Straw Mulch The most effective erosion control practice (both in terms of protection and cost) is the use of cover crop and straw mulch. Straw provides a cushion between the disturbed soil and the velocity of the raindrop. It’s the best insurance for protection from the early rains if you cannot plant your cover crop in mid-September and irrigate it.
In order for straw to be effective, you must apply it at the rate of two tons per acre (about 42 bales per acre). You should not be able to see any soil once the straw is
Rice straw is the cleanest straw available (in terms of other weed seeds) but it is a coarse straw and therefore takes longer to degrade. Any straw or grass hay will work provided it’s applied at the rate of two tons per acre.
If you are in an area that has high winds in the fall you must anchor your straw into the ground. You can do this by tracking it in (see example) or by crimping it.
Otherwise, be prepared to replace the straw that gets blown away.
Keep extra straw bales stored for emergency erosion control repairs. If you have an area that starts to gully you can stuff the gully with straw. You can also build emergency dikes to control drainage (see sediment barrier example).
9 Example 3.2 Tracking Straw Mulch
1. Roughen slope with bulldozer.
2. Broadcast seed and fertilizer.
3. Spread straw mulch 3” thick (2 tons/acre).
4. Punch straw mulch into slope by running bulldozer up and down the slope.
5. Tracking with machinery on sandy soil provides roughening without undue compaction.
Example3.3 Straw Bale Sediment Barriers 10 Straw Wattles Straw wattles or fiber rolls are designed to slow down runoff, filter and trap sediment before the runoff gets into watercourses.
Straw wattles are porous and allow water to filter through fibers and trap sediment. They also slow down runoff thereby reducing sheet and rill erosion.
11 Example 3.4 Straw Wattle Installation
CHAPTER FOUR12 CHAPTER FOUR-Drainage Drainage systems should be designed and maintained to maximize infiltration and minimize sediment delivery to stream by dissipating flow energy, spreading flow, and encouraging infiltration. Drainage systems need to be periodically monitored and maintained to address erosion issues before they cause severe erosion or require costly repairs. It is better to have numerous discharge points in order to avoid the scouring effects of concentrated flow. Drainage systems can, and in some cases should, be designed to discharge into an off-channel water supply reservoir rather than directly to streams.
Drainage systems in new vineyards/orchards or replants in Sonoma County are required by county ordinance to be designed for at least a 25year storm. They can require design or design approval by an approved civil engineer and should incorporate natural features of the landscape (such as swales) into the drainage system.
Environmental Concerns Excess fine sediment suffocates developing salmonid embryos, reduces the availability of invertebrate prey to juvenile salmonids, reduces the depth of pools used for rearing, and embeds spawning gravels. Drainage systems should be designed to allow for infiltration and filtration of fine sediment to maintain quality instream habitat conditions for salmon and steelhead.
Drainage systems that rapidly transport rainfall to a stream increase peak flows and decrease groundwater recharge. Changing the natural hydrograph can act as a barrier for fish migrating upstream as adults or downstream as smolts.
Site Evaluation Inventory all streams, natural drainage swales, wetlands and ponds, existing drainage structures such as culverts under roads, drainage ditches, inlets, outfalls, and sediment ponds.
Evaluate any existing erosion problems and unstable areas.
Best Management Practices 4.1 In accordance with the Sonoma County Grading Drainage and Vineyard and Orchard Site Development Ordinance, design drainage system to handle a 25-year storm; obtain designs or design approval from a civil engineer as required.
4.2 Incorporate natural drainage features into the vineyard/orchard plan to maintain natural sheet flow whenever possible. Consider using vegetated swales as an option to drain pipe whenever possible.
4.3 Monitor vegetated swales for signs of instability, especially in vineyards/orchards with more than minimal slopes and where water has been concentrated into the swale. Consider reinforcing swales with geotextile fabric or grade control structures for additional stability.
13 4.4 Spread and slow flows by incorporating the following BMP options into the drainage system: