Integrated Noxious Weed Management Plan for the North Meadows Extension to US 85 and Interstate 25

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1 for the North Meadows Extension to US 85 and Interstate 25 February 2010 Prepared for: Town of Castle Rock Douglas County Colorado Department of Transportation Federal Highway Administration Prepared by: Alpine Ecological Resources, LLC 1127 Adams Street Denver, CO CDOT Project CC Douglas County Project CI FHU Project No

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3 TABLE OF CONTENTS Page 1.0 Introduction General Site Description Colorado Noxious Weed List Methods Project Limitations Survey Methods Results General Results Results by Habitat Weed Management Management Goal Management Objectives Priorities for Weed Management Weed Management Actions Weeds of Upland Habitats Weeds of Moist Habitats Other Management Actions Conclusion References Page i

4 LIST OF FIGURES Page Figure 1 Study Area Figure 2 Noxious Weed Mapping LIST OF TABLES Table 1 Colorado Noxious Weed Species Observed in the Project Area Appendix APPENDIX A Site Photographs Page ii

5 1.0 INTRODUCTION The North Meadows Extension Project to US Highway 85 (US 85) includes the proposed extension of North Meadows Drive from The Meadows area to US 85 and Interstate (I-25) in the Town of Castle Rock in Douglas County, Colorado (Figure 1 Site Location). The proposed project would cross the Burlington Northern Santa Fe (BNSF) railway, East Plum Creek, and the Union Pacific Railroad (UPRR). The project would include the extension of existing North Meadows Drive to an improved intersection or new interchange with US 85 and a new interchange with I-25. For the purposes of this document, the project area is defined as the area of potential ground disturbance for the project, plus a 100-foot buffer (Figure 2 Noxious Weed Mapping). 1.1 General Site Description The project area is located in central Douglas County, Colorado, in the Great Plains-Palouse Dry Steppe Province (NationalAtlas 2008). This province is characterized by rolling plains and tablelands of moderate relief covered by short-grass prairie (or steppe) that is generally dominated by sparsely distributed bunch grasses. This province lies in the eastern rain shadow of the Rocky Mountains and is considered a semiarid continental regime. The project area is situated between I-25 and US 85 at approximately 6,100 feet above mean sea level. The area has an average annual precipitation of approximately 17 inches and annual mean temperature of 45 degrees Fahrenheit (NationalAtlas 2008). East Plum Creek bisects the project area, and the hydrologic unit code for the watershed is (Upper South Platte). According to the Ecological Assessment Technical Memorandum for the North Meadows Extension to US 85 and Interstate 25 (AlpineEco 2008), the project area contains seven vegetative cover types, including: Grass Dominated Rangeland dominated by mostly native grasses that have been recently disturbed by human activities Urban consists of landscaped areas, paved roads, parking lots, pedestrian trails, residential and commercial property, and areas of mostly bare ground Grass and Cactus Mix dominated by native grasses and cactus, and is relatively undisturbed with a likely history of light to moderate grazing Riparian includes those habitats that are associated with waterways, including wetlands Ponderosa Pine/Gambel Oak contains many species from the Grass and Cactus Mix community Mesic Mountain Shrub common along the small bluffs above the East Plum Creek floodplain and along the ridgelines between I-25 and US 85 Ponderosa Pine Woodland concentrated along the floodplains of East Plum Creek and its tributaries Page 1

6 1.2 Colorado Noxious Weed List The Colorado Noxious Weed Act requires the control of the 71 plant species designated noxious weeds. According to the Colorado Department of Agriculture, noxious weeds are plants that reduce agricultural productivity, lower real estate values, endanger human health and well-being, and damage scenic values (Colorado 2008). The state has divided the 71 noxious weeds into three groups: Lists A, B and C. List A includes 18 plant species that have very limited distribution in Colorado and are designated for immediate eradication. List B includes 39 species that are locally common but are managed to stop continued spreading. List C includes 14 species that are generally widespread and are not managed to stop spreading but to provide additional education, research, and biological control. Page 2

7 2.0 METHODS 2.1 Project Limitations As a result of right-of-entry complications, much of the project area between I-25 and US 85 was not accessible (Figure 2 Noxious Weed Mapping). However, portions of this area are generally visible from several public rights-of-ways, including I-25, US 85, Factory Shop Boulevard, and other local roadways. The areas that were not visible are shown as No Access on Figure 2 Noxious Weed Mapping. 2.2 Survey Methods Andy Herb (senior ecologist) walked the project area on September 7 and 8, 2008 and June 10, 2009 to identify and map noxious weeds. All noxious weed locations were recorded in the field on 1-inch equals 200 feet color aerial photographs or with a global positioning system (GPS) unit accurate to less than 1 meter. Plant nomenclature in this report follows the Colorado Department of Agriculture website (Colorado 2008). Page 3

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9 3.0 RESULTS A total of 17 plant species designated as noxious weeds by the State of Colorado were found in the project area, including 13 List B species and four List C species. No List A species were found. All of the noxious weeds found in the project area are listed in Table 1 with their general distribution, preferred habitat, whether they were found in well-defined populations, and the area of well-defined populations. 3.1 General Results Nearly the entire project area contains one or more of the species listed in Table 1 Colorado Noxious Weed Species Observed in the Project Area. As a result of the widespread nature of most of these species, only discrete and relatively dense populations were mapped. This mapping includes polygons for 13 of the 17 species listed in Table 1 Colorado Noxious Weed Species Observed in the Project Area and is shown on Figure 2 Noxious Weed Mapping. Most of the discrete noxious weed populations are found along existing roadways, especially within a few hundred feet of I-25 and US 85. The area just west of US 85 has the most weed diversity and the most well-defined weed populations, including discrete populations of nine different species (Figure 2 Noxious Weed Mapping). The most common overall weed species found in the project area are downy brome, field bindweed, and diffuse knapweed. Diffuse knapweed is scattered throughout most of the project area and is the most common species found in well-defined populations, covering over 52 percent (13.34 acres) of the 25.6 acres of mapped populations (Table 1 Colorado Noxious Weed Species Observed in the Project Area). 3.2 Results by Habitat Seven of the 17 noxious weed species found in the project area generally prefer upland habitats (Table 1 Colorado Noxious Weed Species Observed in the Project Area). Plants of these species range from few to abundant throughout the majority of the project area, especially in areas that have been recently disturbed (within five years). The most common of these species are downy brome and field bindweed. Both of these plants tend to be present in nearly all upland habitats, including numerous small areas of relatively undisturbed Grass and Cactus Mix. Ten of the 17 noxious weeds found in the project area generally prefer riparian or other moist habitats (Table 1 Colorado Noxious Weed Species Observed in the Project Area). Plants of these species range from few to common in any areas that have (1) relatively high groundwater (especially true for Russian olive and saltcedar), (2) experience some flooding from surface water flows, including stormwater runoff, or (3) are somewhat shaded and/or hold snow longer than adjacent areas. The most common of these species are Canada thistle and hoary cress. Several noxious weeds usually found in upland habitats were also found in moist habitats (usually in very low densities), especially diffuse knapweed, musk thistle, common mullein, and field bindweed. The East Plum Creek corridor has a very diverse hydrologic regime and supports relatively low densities of nearly all the noxious weed species observed in the project area. The only species not observed in this portion of the project area are saltcedar and bull thistle, but both were observed along other reaches of the creek and are expected to be present. Page 5

10 Table 1 Colorado Noxious Weed Species Observed in the Project Area1 Common Name Scientific Name General Habitat General Distribution in Appropriate Habitats Found in Well- Defined Populations Area of Well- Defined Populations (acres) List B Species Hoary cress Musk thistle Diffuse knapweed Canada thistle Bull thistle Houndstounge Russian olive Redstem filaree Leafy spurge Perennial pepperweed Scentless chamomile Scotch thistle Saltcedar List C Species Common burdock Downy brome Field bindweed Common mullein Cardaria draba Carduus nutans Centaurea diffusa Cirsium arvense Cirsium vulgare Cynoglossum officinale Elaeagnus angustifolia Erodium cicutarium Euphorbia esula Lepidium latifolium Matricaria perforata Onopordum acanthium Tamarix ramosissima Arcticum minus Bromus tectorum Convolvulus arvensis Verbascum thapsus 1 No List A Species were observed in the project area Riparian habitats and moist areas Open, upland areas Open, upland areas Riparian habitats and moist areas Riparian habitats and moist areas Riparian habitats and moist areas Riparian habitats and moist areas Open, upland areas Riparian habitats and moist areas Riparian habitats and moist areas Riparian habitats and moist areas Open, upland areas Riparian habitats and moist areas Riparian habitats and moist areas Open, upland areas Open, upland areas Open, upland areas Common Yes 0.17 Common Yes 0.15 Common Yes Abundant Yes 1.29 Few No 0.00 Few Yes 0.08 Few Yes 0.04 Common Yes 5.32 Few Yes 0.13 Few Yes 0.01 Few No 0.00 Common Yes 4.52 Few Yes 0.02 Few Yes 0.07 Abundant No 0.00 Abundant Yes 0.44 Common No 0.00 Total 25.6 Page 6

11 4.0 WEED MANAGEMENT In order to effectively manage noxious weeds, management actions must be implemented in accordance with specific goals and priorities. These are discussed in the following sections. 4.1 Management Goal The goal of this plan is to help maintain the health of the ecosystem in the project area by avoiding additional spreading of noxious weeds as a result of project construction. 4.2 Management Objectives Noxious weed management objectives are intended to support the overall management goal of maintaining the health of the ecosystem. There are two main management objectives and they include: Preventing the establishment of new noxious weed populations in the project area as a result of project construction Preventing the continued spreading of noxious weeds in the project area as a result of project construction These objectives will generally be met by: Pre-treating all noxious weed populations in areas where topsoil salvage is planned Properly revegetating all disturbed areas Specific management actions that will help ensure the success of the objectives are listed in Section 5.0 Weed Management Actions. 4.3 Priorities for Weed Management Weed management priorities are based on the threat noxious weed species found in the project area pose to the overall goal of maintaining the health of the ecosystem. Generally, List A species are the highest priority because they are often the most aggressive species with limited distribution. Since no List A species were found in the project area, List B species are the top priority. Of the 13 List B species found in the project area, four are commonly found in upland areas and nine are commonly found in moist habitats. Although well-defined populations of these species may not have been identified in all areas, all List B species listed in Table 1 Colorado Noxious Weed Species Observed in the Project Area can be expected to be present in all areas of appropriate habitat. Thus, the weed management actions listed in Section 5.0 Weed Management Actions should be implemented in all areas of planned topsoil salvage (at a minimum) according to habitat type. Page 7

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13 5.0 WEED MANAGEMENT ACTIONS The best technique for controlling most noxious weeds is an integrated approach of chemical, mechanical, biological, and cultural controls as described below: Chemical control involves the application of one or more herbicides at the appropriate time of the year (all herbicides should be applied by a certified applicator according to the manufacturer s directions). Mechanical control usually involves mowing, hand-pulling, or cutting. Biological control is the use of organisms (usually insects, but also livestock) that are deliberately introduced to an area to control weeds. Cultural controls seek to control weeds by establishing desired plant species through cultivating, re-seeding, irrigating, etc. All controls should be coordinated with the local county weed supervisor. Of the 17 noxious weed species observed in the project area, 13 were found in discrete populations that are feasibly treatable. All of these well-defined noxious weed populations are List B species, except for common burdock and field bindweed which are List C (Table 1 Colorado Noxious Weed Species Observed in the Project Area). The recommended specific management actions for these species are discussed in the following sections and are adapted from Creating an Integrated Weed Management Plan (Colorado 2000) and the Colorado Department of Agriculture website (Colorado 2008). 5.1 Weeds of Upland Habitats Of the 13 noxious weed species that were found in discrete populations in the project area, five are generally found in dry upland habitats. Information on these five species and the recommended management actions for each are presented below. Musk Thistle Description: Musk thistle is a biennial List B species that establishes best on bare, well-drained soils with a ph range between 6.0 and 8.9 (Photo 1). It has alternate dark green leaves with a solitary purple flower 1.5 to 3 inches in diameter that is usually nodding. It has a fleshy taproot and can appear solitary or with several stems from one base. It can grow as much as 6 feet tall and it only reproduces by seed, which can remain viable in the soil for up to 10 years. It is native to Eurasia. Chemical Control: Picloram is the most effective herbicide for musk thistle, when applied in spring to rosettes. Aminopyralid, metsulfuron, and chlorsulfuron can be somewhat effective on bolted plants in late spring/early summer. Mechanical Control: Repeated mowing, hand pulling, or cutting can be effective if done before seeding. Biological Control: Several insect species can be effective, including the seed head weevil and the crown weevil. These are best used on large infestations. Page 9

14 Control Summary: The key to successful control is to prevent seed production. Spray rosettes with picloram in the spring and reseed treated ground with competitive desirable plants. Herbicide application should be followed-up with annual spot cutting (just before flowering) to deplete the seed bank in the soil. Scotch Thistle Description: Scotch thistle is a biennial List B species that is often found along roadsides and in waste places (Photos 2 and 3). It has very large alternate leaves that are covered with long cotton-like hairs. Flower heads are 1 to 2 inches in diameter, purple, and numerous. It has a fleshy taproot and can grow as much as 12 feet tall. It only reproduces by seed, which can remain viable in the soil for up to 30 years. It is native to Eurasia. Chemical Control: Picloram, aminopyralid, and metsulfuron are the most effective herbicides for scotch thistle, when applied to rosettes in the spring or fall. Metsulfuron can be effective on bolted plants in the spring. Mechanical Control: Repeated mowing, hand pulling, or cutting can be effective if done before seeding, although plants can re-grow from severed roots. Biological Control: Urophora stylata can be used to help control scotch thistle in some areas. Control Summary: The key to successful control is to spray rosettes with picloram, aminopyralid or metsulfuron, and reseed treated ground with competitive desirable plants. Herbicide application should be followed-up with annual spot cutting (just before flowering) to deplete the seed bank in the soil. Diffuse Knapweed Description: Diffuse knapweed is a biennial List B species that is often found in plains and rangelands on light, dry, porous soil (Photo 4). It has small alternate leaves on the stem and larger much divided basal leaves. Flowers are very numerous, only 0.6 to 0.8 inches in diameter, and either white or purple. It has a taproot and only reproduces by seed, which can remain viable in the soil for up to several years. It is native to Eurasia. Chemical Control: Aminopyralid, 2,4-D, clopyralid with triclopyr, and picloram are the most effective herbicides for diffuse knapweed. All herbicides will be most effective if applied to the rosettes in the spring or fall. A non-ionic surfactant should be added to all herbicides. Mechanical Control: Cutting or mowing can reduce seed production, but will not eliminate the infestation. Mowing can sometimes increase plant density by increasing germination from the soil seed bank, so it should be followed by herbicide application. Pulling can be effective, but must be repeated frequently.fire can be effective in some areas. Biological Control: There are six insect species that may provide biological control, but their effectiveness is unclear. Control Summary: The key to successful control is to spray rosettes in the spring or fall, reseed treated ground with competitive desirable plants, and follow-up with spot treatments with picloram or hand-pulling. Page 10

15 Redstem Filaree Description: Redstem filaree is a winter annual or biennal List B species that is in a wide range of habitats with well-drained soils (Photo 5). It has narrow feather-like lobed or toothed leaves that are covered with small hairs. Flowers are pink and generally born in clusters of two or more. It has a slender taproot up to 3 inches long with secondary fibrous roots. It only reproduces by seed, which can remain viable in the soil for many years. It is native to Eurasia. Chemical Control: 2,4-D or dicamba are the most effective herbicides for redstem filaree. Glufosinate is not effective. Mechanical Control: Mowing or burning after flowering, but before seeding can eliminate seed production. Biological Control: None known. Control Summary: The key to successful control is to eliminate seed production using a combination of herbicide and mechanical removal. Field Bindweed Description: Field bindweed is a perennial List C species that is commonly found in cultivated areas, pastures, lawns, gardens, roadsides, and waste areas. It has arrow-shaped leaves and grows close to the ground. Flowers are white to pink and are bell or trumpet shaped. It has a very deep taproot (up to 20 feet long) that will produce many horizontal roots (rhizomes). It also reproduces by seed, which can remain viable in the soil for up to 40 years. It is native to Europe. Chemical Control: Glyphosphate, picloram, dicamba, and 2,4-D are the most effective herbicides for field bindweed. Control is best when applied during early flowering and when soil moisture is low. Mechanical Control: Mechanical controls have little effect unless the plants are cut below the surface in the early seedling stage. Biological Control: The bindweed gall mite (Aceria mahlerbae) can be effective. Control Summary: The key to successful control is to contain and persistently stress the plant in order to exhaust the root system and deplete the soil seed bank. This is best done by repeated foliar applications of herbicide. 5.2 Weeds of Moist Habitats Of the 13 noxious weed species that were found in discrete populations in the project area, eight are generally found in riparian or other moist habitats. Information on these species and the recommended management actions for each are presented below. Canada Thistle Description: Canada thistle is a perennial List B species that infests croplands, pastures, rangelands, roadsides, and riparian areas (Photo 6). It has spiny alternate green leaves with a numerous purple flowers less than 1 inch in diameter. It has two types of roots, horizontal and vertical. The horizontal roots produce many shoots, while the vertical roots store water and Page 11

16 nutrients. It is usually 2 to 4 feet tall and reproduces primarily by the horizontal roots (all root fragments are capable of forming a new plant) and seed, which can remain viable in the soil for several years. It is native to Eurasia. Chemical Control: Aminopyralid, 2,4-D combined with clopyralid, chlorsulfuron, or picloram are the most effective herbicides. All will be most effective when sprayed on rosettes or during bud stage. Mechanical Control: Mowing can be effective if it is done monthly through the growing season. Burning can be effective in some situations. Biological Control: No single biological control agent has been shown to be effective. However, a gall fly (Urophora cardui) may provide limited control. Cattle, goats, and sheep will graze on Canada thistle when it is young (in the spring) and, when combined with herbicide application, may be effective. Control Summary: The tendency of this species to grow in wet areas may restrict the use of certain herbicides. Successful control will involve spraying in the spring and/or fall (depending on moisture conditions), combined with mowing and/or grazing. Houndstounge Description: Houndstounge is a biennial List B species that grows on rangeland, pastures, roadsides, and riparian areas with gravelly somewhat alkaline soils. It has large alternate leaves 1 to 12 inches long with reddish-purple flowers with five petals. It has a thick, black, woody taproot. It is usually 1.5 to 3 feet tall and reproduces only by seed, which can remain viable in the soil for 2 to 3 years. It is native to Eurasia. Chemical Control: Picloram with 2,4-D or metsulfuron with chlorsulfuron are most effective and should be used in the spring on rosettes. Mechanical Control: Mowing during flowering (before seeding) can kill the plant. Biological Control: A root weevil has been successful in some sites, but is not yet approved in Colorado. Control Summary: The tendency of this species to grow in wet areas may restrict the use of certain herbicides. If possible, treat first year plants (rosettes) with herbicide and mow bolted plants. Repeat this process for several years to exhaust the seed bank. Common Burdock Description: Common burdock is a biennial List C species that grows along roadsides, ditchbanks, and riparian areas with moist, fertile soils. It has very large, hairy, heart-shaped rosette leaves with purple flowers in clusters at the ends of the branches. It has a large, fleshy taproot. It grows up to 7 feet tall and reproduces only by seed. It is native to Eurasia. Chemical Control: Picloram, 2,4-D, dicamba, or glyphosate are most effective in when applied to first-year rosettes. Mechanical Control: Tilling can kill plants that are in the rosette stage. Mowing or cutting after the plant has bolted, but before flowering, can eliminate seed production. Biological Control: None known. Page 12

17 Control Summary: The tendency of this species to grow in wet areas may restrict the use of certain herbicides. If possible, treat first year plants (rosettes) with herbicide or tilling, and mow bolted plants. Repeat this process for several years to exhaust the seed bank. Hoary Cress Description: Hoary cress or whitetop is a perennial List B species that grows well on alkaline soils that are wet in the spring (Photo 7). It is commonly found in fields, meadows, pastures, and in riparian areas. It has alternate leaves 1.6 to 4 inches long and numerous white flowers with four petals. It has rhizomatous roots that typically occur at depths of 29 to 32 inches. It grows up to 2 feet tall and reproduces by seed and by creeping roots. It is native to Eurasia. Chemical Control: Metsulfuron and chlorsulfuron are most effective during the early bud-stage (early May or June). Imazapic can be effective during the late flowering to post-flowering stage. Mechanical Control: Mowing two or three times per year for several years can reduce spreading and seed production, and may increase the effectiveness of herbicides. Mowing should be done during the bud stage and repeated when the plants rebud. Fire may benefit hoary cress and is not recommended. Biological Control: None are certain. Sheep grazing may be helpful, but it must be closely managed to avoid adverse affects to desirable plants. Control Summary: The tendency of this species to grow in wet areas may restrict the use of certain herbicides. If possible, treat plants with herbicide in the spring and follow with mowing. Russian Olive Description: Russian olive is a perennial List B species that can grow in a variety of soil and moisture conditions, but prefers open, moist, riparian areas. It has alternate, narrow, leaves 2 to 3 inches long that are white on the underside. It grows up to 30 feet tall and reproduces by both roots and seed, which can remain viable for up to 3 years in the soil. It is native to Eurasia. Chemical Control: Triclopyr and imazapyr are the most effective herbicides. Both should be applied to the cambial layer of the tree immediately after cutting (cut-stump treatment). Mechanical Control: Mowing or cutting can be effective, but often must be combined with either herbicides or excavation of the entire stump. Burning can be effective if conditions can support a long, hot fire. Biological Control: Tubercularia canker can be effective. Control Summary: The best control of Russian olive is the cut-stump treatment, which involves cutting and herbicide application. This method is most effective during the winter months. Mowing can be effective in some situations. Saltcedar Description: Saltcedar is a perennial List B species that grows well on moist soils. It can tolerate highly saline habitats and is common on floodplains and in riparian areas. It has minute, scaly leaves and white or pink flowers grouped together in terminal panicles. It grows up to 15 feet tall and reproduces by both roots and seed, which can remain viable for up to 45 days in the soil. The seeds have no dormancy requirements and can germinate within 24 hours following contact with water. It is native to Eurasia. Page 13

18 Chemical Control: Triclopyr, glyphosate, and imazapyr are the most effective herbicides. All should be applied to the cambial layer of the tree immediately after cutting (cut-stump treatment). Mechanical Control: Mowing, fire, or clearing with a bulldozer can be effective to open up large stands, but must be combined with herbicide application once the resprouts are 1 to 2 meters tall. Biological Control: The saltcedar leaf beetle (Diorhabda elongata) larvae and adults feed on saltcedar foliage and can be effectively used to control the plant. Control Summary: The best control of saltcedar is the cut-stump treatment, which involves cutting and herbicide application. This is most effective during the winter months. Biological control can be the best choice in some situations. Perennial Pepperweed Description: Perennial pepperweed is a List B species that grows well on saline soils in riparian areas and other seasonally wet locations. It has alternate leaves that are lance-shaped and can grow up to 5 feet tall. It has tiny white flowers that are clustered at the branch tips. It reproduces primarily from deep roots and root pieces, but can also reproduce from seed. It is native to Eurasia. Chemical Control: Metsulfuron, chlorsulfuron, and imazapyr are the most effective herbicides for controlling perennial pepperweed. All should be applied during spring or early summer when the plant is bolting or flowering. Mechanical Control: Due to the deep and brittle root system, most mechanical controls are not effective and can actually increase plant density. However, spring mowing combined with chemical application can be effective. Biological Control: No biological controls are available. Control Summary: The tendency of this species to grow in wet areas may restrict the use of certain herbicides. The best control is to combine mowing with herbicide application (on recovering plants) in the spring. Leafy Spurge Description: Leafy spurge is a perennial List B species that spreads by seed and extensive creeping roots. It is commonly found in rangeland, pastures, and riparian areas. It has narrow alternative leaves 1 to 4 inches long and numerous yellowish-green flowers in small clusters subtended by paired heart-shaped yellow-green bracts. It grows up to 3 feet tall and contains a white, milky sap that can damage eyes and sensitive skin. Chemical Control: Picloram or picloram with 2,4-D are the most effective herbicides for leafy spurge. Others that can be effective are fosamine, imazapic, and 2,4-D amine. Picloram and fosamine should be applied in the spring, whereas the others can be applied in the fall. Mechanical Control: Hand-pulling is not effective. Mowing will reduce seed productions but will not provide long-term control. Biological Control: Both sheep and goats can be effective controls. Also, several flea beetles (Apthona spp.) can be effective when combined with grazing and/or herbicides. Page 14

19 Control Summary: The most effective approach to controlling leafy spurge is to combine multiple treatments, including grazing, herbicide application, and use of insects. 5.3 Other Management Actions In addition to the specific Management Actions listed for each species above, the following general actions will be implemented (as appropriate) to minimize the spread of noxious weeds: The area of ground disturbance will be kept to the minimum necessary Minimize imported topsoil during construction. If necessary use certified weed-free soil. All construction equipment will remain on designated roadways and stay out of untreated weed-infested areas. Fencing will be used to identify these areas. All equipment will be thoroughly cleaned before entering and exiting the project area Areas with dense and well-defined noxious weed populations (those shown on Figure 2 Noxious Weed Mapping) will not be used for topsoil salvage All areas planned for topsoil salvage will be treated for noxious weeds prior to salvage All noxious weed treatments will be coordinated with the Douglas County Weed Supervisor Only a Colorado licensed Supervisor or Certified Operator will apply herbicides All herbicides will be applied in accordance to the manufacture s instructions Only herbicides approved for use in water will be used in or within 25 feet of wetlands or other water features Herbicides will be applied with wicks or sponges to avoid off-target application Broadcast herbicide spraying will only be approved through written consent of the Engineer and shall be applied when weather conditions (including wind) are suitable for such work. Engineer will be notified 24 hours prior to herbicide application All mulches and erosion bales used at the site will be certified weed-free The project area will be surveyed for noxious weeds during design and throughout construction to identify and treat weeds Reseeding will consist of native grasses and forbs, and seeding should be phased throughout construction (as appropriate) to minimize the amount of open ground All seed mixes, soil, and other plant material used for revegetation will be free of noxious weed seeds, roots, and other propagules No fertilizers will be used during revegetation efforts Any revegetation that is undertaken in the East Plum Creek riparian conservation zone will be consistent with the Douglas County Habitat Conservation Plan (Douglas County and the Towns of Parker and Castle Rock, 2005) Page 15

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21 6.0 CONCLUSION The goal of this plan is to help maintain the health of the ecosystem in the project area by avoiding additional spreading of noxious weeds. There are two main objectives and they include preventing the establishment and continued spreading of noxious weed populations in the project area as a result of project construction. These objectives will generally be met by pretreating all noxious weed populations in areas where topsoil salvage is planned; properly revegetating all disturbed areas; and monitoring revegetation efforts for noxious weeds combined with treating those populations as appropriate. Weed management priorities are based on the threat noxious weed species found in the project area pose to the overall goal of maintaining the health of the ecosystem. Generally, List A species are the highest priority because they are often the most aggressive species with limited distribution. Since no List A species were found in the project area, List B species are the top priority. The best technique for controlling most noxious weeds is an integrated approach of chemical, mechanical, biological, and cultural controls. All controls should be coordinated with the local county weed supervisor. A total of 17 plant species designated as noxious weeds by the State of Colorado were found in the project area, including 13 List B species and four List C species. Nearly the entire project area contains one or more of the 17 species. As a result of the widespread nature of most of these species, only discrete and relatively dense populations were mapped. This mapping includes polygons for 13 of the 17 species. Of the 13 noxious weed species that were found in discrete populations, five are generally found in dry upland habitats and eight are generally found in riparian or other moist habitats. This plan includes specific weed management actions for all 13 of these species. Page 17

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23 7.0 REFERENCES AlpineEco Ecological Assessment Technical Memorandum for the North Meadows Extension to US 85 and Interstate 25. Prepared for Town of Castle Rock, Douglas County, Colorado Department of Transportation, and Federal Highway Administration. In association with Felsburg Holt & Ullevig. July 22. Colorado Department of Agriculture (Colorado) Creating An Integrated Weed Management Plan. Caring for the Land Series, Volume IV. Prepared with Colorado Natural Areas Program, Colorado State Parks, and Colorado Department of Natural Resources. March. Colorado Department of Agriculture (Colorado) Noxious weed website: Accessed in October. Douglas County and the Towns of Parker and Castle Rock Habitat Conservation Plan and for Douglas County and the Towns of Castle Rock and Parker. October. NationalAtlas Website for Bailey s Ecoregions: Page 19

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25 Figure 1 Study Area Page 21

26 Figure 2 Noxious Weed Mapping Follows on two pages Page 22

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29 APPENDIX A SITE PHOTOGRAPHS Appendix A

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31 Photo 1 Musk thistle rosette in the East Plum Creek corridor Photo 2 Scotch thistle between US 85 and the Union Pacific Railroad Appendix A-1

32 Photo 3 Large area of scotch thistle between US 85 and East Plum Creek Photo 4 Diffuse knapweed between US 85 and East Plum Creek Appendix A-2

33 Photo 5 Dense carpet of redstem filaree just east of East Plum Creek Photo 6 Pocket of Canada thistle beneath ponderosa pine trees along Interstate-25 Appendix A-3

34 Photo 7 Dense patch of hoary cress above East Plum Creek Appendix A-4