8920 EVERGREEN WAY THE RESERVE 2025-07-25

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL • soluble form of nutrients that can be added to the soil. Composted organic matter generally releases only between 2 and 10 percent of its total nitrogen annually,and this release corresponds closely to the plant growth cycle. If natural plant debris and mulch are returned to the soil,this system can continue recycling nutrients indefinitely. 2. Select the appropriate turf grass mixture for the climate and soil type. Certain tall fescues and rye 40 grasses resist insect attack because the symbiotic endophytic fungi found naturally in their tissues repel or kill common leaf and stem-eating lawn insects. They do not,however,repel root-feeding lawn pests such as Crane Fly larvae,and are toxic to ruminants such as cattle and sheep. The 40 fungus causes no known adverse effects to the host plant or to humans. Endophytic grasses are commercially available and can be used in areas such as parks or golf courses where grazing does not occur. The local Cooperative Extension office can offer advice on which types of grass are w best suited to the area and soil type. 3. Use the following seeding and planting BMPs,or equivalent BMPs,to obtain information on 40 grass mixtures,temporary and permanent seeding procedures,maintenance of a recently planted area,and fertilizer application rates: Temporary Seeding,Mulching,and Matting;Clear Plastic Covering;Permanent Seeding and Planting; and Sodding as described in Volume II,Construction • Stormwater Pollution Prevention. 4. Selection of desired plant species can be made by adjusting the soil properties of the subject site. For example, a constructed wetland can be designed to resist the invasion of reed canary grass by layering specific strata of organic matters(e.g.,compost forest product residuals)and creating a mildly acidic pH and carbon-rich soil medium. Consult a soil restoration specialist for site- specific conditions. 5. Aerate lawns regularly in areas of heavy use,where the soil tends to become compacted. Aeration should be conducted while the grasses in the lawn are growing most vigorously. Remove layers of thatch greater than 3/4-inch deep. 40 6. Mowing is a stress-creating activity for turf grass. When grass is mowed too short, its productivity is decreased and there is less growth of roots and rhizomes. The turf becomes less tolerant of environmental stresses,more disease prone, and more reliant on outside means such as go pesticides,fertilizers, and irrigation to remain healthy. Set the mowing height at the highest acceptable level and mow at times and intervals designed to minimize stress on the turf. Generally mowing only one-third of the grass blade height will prevent stressing the turf. 40 Suggested BMPs for Irrigation 40 1. The depth from which a plant normally extracts water depends on the rooting depth of the plant. Appropriately irrigated lawn grasses normally root in the top 6 to 12 inches of soil; lawns • irrigated on a daily basis often root only in the top 1 inch of soil. Improper irrigation can encourage pest problems,leach nutrients,and make a lawn completely dependent on artificial watering. The amount of water applied depends on the normal rooting depth of the turf grass • species used,the available water holding capacity of the soil,and the efficiency of the irrigation • system. Consult with the Snohomish Conservation District,or WSU Cooperative Extension office to help determine optimum irrigation practices. Suggested BMPs for Fertilizer Management 1. Turf grass is most responsive to nitrogen fertilization,followed by potassium and phosphorus. Fertilization needs vary by site depending on plant,soil,and climatic conditions. Evaluation of soil nutrient levels through regular testing ensures the best possible efficiency and economy of • Volume IV—Source Control 3-24 f