Section No.5: Section No.6: Section No.7: Section No.8:

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2 HIGH LINE CANAL PRESERVATION AND ENHANCEMENT PLANNING STUDY TABLE OF CONTENTS: August 21, 2012 Project Introduction. Pages No.1 No.2 Executive Summary. Page No.1 No.4 Section No.1: Existing Conditions Inventory and Documentation Introduction.. Page No.1 of 1 High Line Canal Study Area Map..... Page No.1 of 1 Planning Study Limits and Sheet Index... Page No.1 of 1 Existing Conditions Inventory and Documentation Plan and Photo Sheets.. Page No.1 No.65 Section No.2: Spatial Character and Experiential Quality Analysis Introduction Page No.1 No.2 Spatial Character Analysis Section Sheets Page No.1 No.4 Dynamic View Shed Analysis Plan Sheet Page No.1 of 1 Section No.3: Land Use and Circulation Analysis Introduction. Page No.1 of 1 High Line Canal Trail Linkages Plan. Page No.1 of 1 Circulation and Land Use Inventory Report. Page No.1 No.3 Circulation and Land Use Inventory Plan Sheets. Page No.1 No.21 Circulation System Improvement Report.. Page No.1 No.5 Circulation System Project Priorities Report... Page No.1 No.2 Section No.5: Vegetation and View Shed Analysis Introduction Page No.1 No.2 Vegetation Screening and View Shed Inventory Sheets... Page No.1 No.21 Tree Inventory Sheets.. Page No.1 No.21 Tree Gallery Evolution Sheets Page No.1 No.9 Section No.6: Sustainability Analysis Report.... Page No.1 No.2 Irrigation Limit / Strategy Concept Diagram... Page No.1 No.1 Section No.7: Signage Improvement and Standardization Analysis Introduction... Page No.1 of 1 High Line Canal Signage Inventory Report... Page No.1 of 2 High Line Canal Signage Inventory Plan Sheets..... Page No.1 No.5 High Line Canal Signage Improvement Report... Page No.1 of 2 High Line Canal Sample Trail Sign.... Page No.1 of 1 High Line Canal Sample Interpretative Sign.... Page No.1 of 1 Transit System Concept Sheet... Page No.1 of 1 Section No.8: Opportunity and Possibility Implementation Process Study.. Page No.1 of 1 Circulation System Improvement Plan Sheets.. Page No.1 No.21 Circulation System Improvement Detail Sheets.... Page No.1 No.4 Section No.4: Wildlife Habitat Preservation and Enhancement Guidelines Introduction. Page No.1 of 1 Wildlife Habitat Preservation and Enhancement Guidelines Report... Page No.1 No.17 1

3 HIGH LINE CANAL PRESERVATION AND ENHANCEMENT PLANNING STUDY PROJECT INTRODUCTION August 21, 2012 INTRODUCTION: Constructed in 1879, the High Line Canal has functioned as a trans-basin water diversion, supplying South Platte River water to numerous agricultural and institutional users along its almost 70 mile length. Over time, as cropland has been developed into a variety of commercial and residential uses, the number of agricultural and institutional consumers of High Line Canal water has been reduced. With the formalization of recreational access agreements in the 1970s, between Denver Water owner and operator of the High Line Canal and the municipalities along is length, the High Line Canal took on the additional role of recreation and trails corridor. In recognition of this evolving character and purpose, Arapahoe County Open Spaces has commissioned this preservation and enhancement planning study to assist in managing and directing the evolving recreational component of the High Line Canal. PROJECT DESCRIPTION: The High Line Canal Preservation and Enhancement Planning Study is a landscape architectural evaluation of the High Line Canal corridor experience through the contiguous portions of Arapahoe County beginning at County Line Road on the south and ending at Hampden Avenue on the north. The study is a multi-level, experientially based, recreation systems analysis and visioning exercise designed to identify potential spin off project opportunities that will preserve and enhance the recreational user experience of the High Line Canal throughout the study corridor. PROJECT OBJECTIVE: The objective of the High Line Canal Preservation and Enhancement Planning Study is to make the recreational experience throughout the High Line Canal study corridor safer, richer and more meaningful for the current generation of High Line Canal users and to preserve the quality of this experience for future generations. MANAGEMENT PLAN STRUCTURE: Each of the study areas identified in the scope of work below is represented as an individual section in the preservation and enhancement planning study. Each section of the study begins with an introduction describing the objective, process, conclusions, considerations, and supporting documentation for that section. The supporting documentation consists of both text and graphic plan sheets at 11 by 17 format. MANAGEMENT PLAN SCOPE OF WORK: Section No.1 Existing Conditions Inventory and Documentation Section No.2 Spatial Character and Experiential Quality Analysis Section No.3 Land Use and Circulation Analysis Section No.4 Wildlife Habitat Preservation and Enhancement Guidelines Section No.5 Vegetation and View Shed Analysis Section No.6 Sustainability Analysis Section No.7 Signage Improvement and Standardization Analysis Section No.8 Opportunity and Possibility Implementation Process Study PROJECT SPONSORS AND MANAGERS: Sponsoring Agency: Arapahoe County Open Spaces Managing Agency: City of Aurora Parks, Recreation and Open Space HIGH LINE CANAL MANAGEMENT PLAN Consulting Team Structure: Prime Consultant Mike Holweger - Landscape Architect - Colorado License No.149 Applied Design Services L.L.C Bayou Ridge Trail Parker, Colorado (303) adsllc@aol.com ERO Resources Corp Andy Cole Natural Resource Specialist 1842 Clarkson St. Denver, Colorado (303) acole@eroresources.com The Architerra Group Mark Taylor Landscape Architect and Trail Planner 5881 S. Deframe St. Littleton, Colorado (303) mtaylor@architerragroup.com 1

4 Visual Environments Mark Button - G.I.S. and Computer Simulation 438 Verdos Dr. Elizabeth, Colorado (303) mark.button@visenv.com MANAGEMENT PLAN FORMAT AND EXTENTS: In order to ensure that this planning study functions effectively as both an in-office planning tool and as a field or operations manual, the study was produced in an 11 by 17 format. The consulting team evaluated a number of alternative scales to show the level of detail necessary for the required analysis and proposed improvements, at the same time keeping the number of individual planning study sheets to a reasonable count. The consulting team organized the study area into logical planning study units to facilitate the efficient collection, evaluation and documentation of information. Alternative scales and planning study area organization formats were conceptualized and presented as options. Base information was procured in the form of aerial photography with one foot pixels. A scale of 1 = 300 was chosen as the best balance between detail and sheet count, which resulted in the designation of 21 planning study units beginning with Sheet No.1 at County Line Road on the south and ending with Sheet No. 21 at Hampden Avenue on the North. ACKNOWLEDGEMENTS: For their patience, support, direction and assistance: Arapahoe County Open Spaces: Mr. Shannon Carter, Special Assistant to the County Commissioners City of Aurora Parks, Recreation and Open Space: Mr. Tom Barrett Director of Parks, Recreation and Open Space Ms. Tracy Young Manager of Planning Design and Construction Ms. Pat Schuler Manager of Open Space and Natural Resources Mr. Christopher Ricciardiello, ASLA Principal Landscape Architect Denver Water: Mr. Neil Sperandeo Recreation Manager Mr. Kevin Keefe Superintendent Source of Supply South Suburban Parks and Recreation: Mr. David A. Lorenz Executive Director Mr. Scott Grimes Forestry / Horticulture Supervisor 2

5 HIGH LINE CANAL PRESERVATION AND ENHANCEMENT PLANNING STUDY EXECUTIVE SUMMARY: August 21, 2012 WHAT WE KNEW: As Hal Borland (American outdoor author and journalist), once said, in the beginning there was the High, Wide and Lonesome, that expansive, high-altitude rain shadow extending from the Rocky Mountains to the tall grass prairies of the Midwest. This high altitude, short-grass prairie was among the last areas of the American West to be homesteaded, and one of the first to be abandoned during the Dust Bowl. Large portions of this semi-arid high desert have been returned to the public domain as national grasslands, because prior to the development of central pivot irrigation, farming in this region was an exercise in frustration and disappointment. WHAT WE LEARNED: Pure ambition is not enough to ensure success. The High Line Canal never fulfilled its expectation of transforming our high altitude, short-grass prairie into productive farm land. The original estimate was that the High Line Canal could provide enough irrigation water to cultivate as much as 80,000 acres of arid short-grass prairie. Because of the junior water right and technological problems with the delivery system, the maximum area irrigated by the High Line Canal between 1887 and 1906 was never more than 25,000 acres, and in 1889 was as low as 7,551 acres. As demonstrated throughout the history of the High Line Canal money is easier to find than water. The history and future of the High Line Canal was and is currently being shaped by forces beyond our control. Global warming and climate change and the resulting drought cycles we are experiencing take the High Line Canal water right out of priority for extended periods. Flows are unpredictable not because of policy but because of resource scarcity. Duff, Nettleton and Eaton, the respective financier, engineer and builder of the High Line Canal, must have all passed in disappointment. However, success can be defined too narrowly and value adjusts over time as scarcity changes in response to need. Little known to the canal s creators, they were to leave us an important legacy, by inadvertently creating a rare and wonderful serpentine trails and open space corridor through our community. Little did they know that the weeds growing along the banks of the canal would become the gallery forest that today surrounds the recreational trail users within a wonder woodland. Every failure brings opportunity and every generation dreams about a future filled with possibilities. Only the current generation, our generation is in a position to preserve and enhance the High Line Canal to its highest and best potential, as the High Line Canal Recreation and Trails Corridor. WHAT IT MEANS: The recreational, maintenance and safety issues surrounding the High Line Canal have been identified in the individual sections of this planning study. All of these issues can be corrected, and we should be encouraged that the preservation and enhancement of the High Line Canal Recreation and Trails corridor is within our grasp. Sustainability is the answer. The High Line Canal is too important as an historically significant, exceptionally unique recreational resource serving a broad spectrum of the community to leave its future in the hands of a changing and unpredictable semi-arid climate. WHAT IS NEXT: Some of the maintenance and safety issues surrounding the High Line Canal are highly complex and will take considerable effort to correct. However, the recommendations for improvements in the individual sections of the planning study are not mutually exclusive. The improvement process is not strictly linear. We can undertake improvements now that will not preclude future preservation and enhancement efforts. This planning study outlines a process for the analysis and decision making required to define a vision for the High Line Canal Recreation and Trails Corridor. By detailing the effort and investment necessary to develop a High Line Canal specific brand that will distinguish this trail system from any other we can begin to realize the canal s recreational potential. There are still questions to be answered, negotiations to be conducted and agreements to be reached, all of which are within our grasp. Everyone interviewed during the preparation of this plan was supportive and optimistic about the preservation and enhancement of the High Line Canal Recreation and Trails Corridor. This planning study provides a framework for the analysis and decision making required to ensure a successful preservation and enhancement effort. Through the implementation of the prioritized improvements listed in the plan, the High Line Canal of the future will, for the first time in its existence, meet the needs of an entire community as the preserved and enhanced High Line Canal Recreation and Trails Corridor, Colorado s new emerald strand. WHAT IS INCLUDED IN THE PLANNING STUDY: SECTION NO.1 EXISTING CONDITIONS INVENTORY AND DOCUMENTATION: The High Line Canal existing conditions inventory and documentation was undertaken to catalog the plan view location and existing conditions of all of the existing trail improvements along the length of the study corridor. A photographic inventory of the study corridor was completed shooting a six shot photographic panorama every 200 along the length of the trail, beginning at County Line Road on the south and ending at Hampden Avenue on the north. 1

6 In addition to the corridor panorama photos, each existing trail improvement was photographed, including pedestrian access points, pedestrian bridges, mile posts, signs, trash receptacles, benches and dog waste stations. All of the trail improvements, as well as the corridor panorama photos, were located in plan using a Trimble sub meter GPS unit. The trail improvements and panorama photo locations represented on plan are within 20 to 30 of their physical location along the corridor. The GPS points were processed, reformatted into AutoCAD, and inserted into each of the 21 aerial base sheets covering the study corridor. Each of the individual trail improvements listed above, including the down-stream panorama photos, were located with color coded targets on plan. Each target was then referenced to a photograph of either the trail improvement or downstream trail photo on the existing conditions tiled photo inventory sheets, inserted between each of the 21 plan sheets along the study corridor. SECTION NO.2 SPATIAL CHARACTER AND EXPERIENTIAL QUALITY ANALYSIS: The High Line Canal spatial character and experiential quality analysis was undertaken to develop a frame work for decision making that will inform, focus and direct an evaluation of the quality and character of the user experience along the canal corridor. This analysis consisted of identifying the components that in combination serve to influence the user experience, then understanding how these components can be combined or modified to best preserve and enhance the value of the canal experience. Spatial Character: The canal was evaluated in sections, beginning with the identification of the five physical elements that go into the 100 wide canal corridor looking downstream from right to left: 1) The high bank frame (the canal slope on the opposite side of the channel from the trail), which varies in width from 15 to 20 and varies in slope from three-to-one to two-to-one. 2) The channel corridor (the water course of the canal), which varies in width from 20 to 22 and is typically 3 deep. 3) The low bank frame (the canal slope between the channel and the trail), which varies in width from 10 to 20 and varies in slope from three-to-one to as steep as one-to-one. 4) The trail corridor (the surfaced section of the trail), which varies in width from 14 to 16 and is crowned or cross sloped for drainage. 5) The shoulder frame (the slope down from the trail to the corridor boundary), which varies in width from 15 to 20 and varies in slope from four-to-one to three-to-one. The high bank frame is covered from channel edge to corridor boundary with dense woody understory vegetation along the entire length of the study corridor. This serves to control views into the residential and in some cases commercial properties located adjacent to and uphill of the canal corridor. Large cottonwood, willow and poplar trees are present along sections of the high bank frame throughout the study corridor. The channel corridor is space defined by the vegetation located on the high and low bank frames. Where large trees are present the corridor is shaped into a linear outdoor room, framed by the arching forms of the trees on both sides. The low bank frame is covered from channel edge to within two-to-three feet of the trail with dense woody understory vegetation along the majority of the upstream reaches of the study corridor, from County Line Road on the south to University Boulevard on the north. The woody understory along the low bank frame progressively thins out and is replaced with native grasses moving north from University Boulevard. Large cottonwood, willow and ash trees are present along sections of the low bank frame throughout the study corridor. The trail corridor is the space defined by the vegetation located on the low bank and shoulder frames, and where large trees are present is shaped into a linear outdoor room framed by the arching forms of the trees on both sides. The shoulder frame is covered from trail edge to corridor boundary with native grasses along the majority of the study corridor, with the exception of sections of dense woody understory vegetation occurring sporadically throughout the study corridor. There are a limited number of large trees located along the shoulder frame, primarily where commercial, institutional or open space properties are adjacent to the study corridor. The entire infill tree planting, done in the early 1990s, is located along the shoulder frame. The spatial character of the study corridor is defined by the presence of open native grasses, woody understory, and large trees along the high bank frame, low bank frame and shoulder frame throughout the study corridor. To understand the different combinations of vegetation massing along the three landscape panels that make up the corridor cross section, and to understand how they define the spatial character of the High Line Canal corridor, a series of illustrative cross section diagrams were developed for analysis. SECTION NO.3 LAND USE AND CIRCULATION ANALYSIS: The High Line Canal land use and circulation analysis was undertaken to enhance the trail experience for users of the High Line Canal Trail by increasing its safety, regional and local circulation system integration, and maintainability. A plan view analysis documenting the existing adjacent land use, circulation system and related infrastructure was prepared for the entire length of the study corridor. Safety issues and circulation improvement opportunities were identified, and a prioritized list of potential spin off projects was developed. SECTION NO.4 WILDLIFE HABITAT PRESERVATION AND ENHANCEMENT GUIDELINES: Wildlife habitat along the High Line Canal is evolving in response to two factors: external pressures from increased recreational use, and internal economic pressure as the role and mission of the canal changes over time. Since wildlife issues affecting the High Line Canal through the study corridor are generally applicable to the entire length of the canal, an alternative strategy for addressing the wildlife component of the planning study was adopted. 2

7 The wildlife enhancement guidelines were prepared as a planning tool. They were intentionally designed for two purposes: to be flexible enough to keep up with and address wildlife issues associated with the ongoing evolution of the canal, and to be adaptable enough to be used to address wildlife issues at any location along the entire length of the High Line Canal. Andy Cole, team natural resource planner and wildlife specialist, prepared a wildlife enhancement guideline document identifying the issues associated with wildlife habitat and defining a process for including wildlife habitat enhancement considerations into the larger open space decision making/planning process. SECTION NO.5 VEGETATION AND VIEW SHED ANALYSIS: The vegetation and view shed analysis was undertaken to evaluate the pattern and distribution of woody understory vegetation (shrubs 8 to 12 tall) along the study corridor, and to understand how the pattern and distribution of this woody understory vegetation affects the user experience in terms of enhancing or obscuring existing views from the canal trail. The maturation of the gallery forest along the canal was projected forward in time to establish the probable effect of existing management policy and maintenance practice on the trees. In addition, it was aimed at illustrating the potential impact of Denver Water Board-approved infill planting along the shoulder side of the trail, opposite from the canal. The existing woody understory vegetation was initially mapped throughout the study corridor from aerial base mapping. The limits were then adjusted through field verification during the location and documentation of existing view sheds. This information was combined into a set of plan sheets, to highlight conditions where future managers could make recommendations for the introduction or removal of understory vegetation, as required to enhance attractive views (primarily of the front range panorama) or to screen objectionable views of properties adjacent to the canal corridor. Using the G.P.S. tree inventory database developed by Denver Water in 2002, the existing trees along the study corridor were mapped showing distribution and size. Each tree was sorted onto a different AutoCAD layer based upon its size. Trees on each size-specific layer where assigned a different illustrative graphic target-symbol, which was roughly equal to the drip line of the tree based on trunk diameter at breast height. Each size target was then assigned a different color to further graphically differentiate the trees as sized. Trees 50 and larger in trunk diameter were assigned a 55 diameter dark green circular drip line targetsymbol. Trees 40 to 50 in trunk diameter were assigned a 45 diameter drip line target-symbol in a successively lighter shade of green. Trees 30 to 40 in trunk diameter were assigned a 35 diameter drip line target-symbol in a successively lighter shade of green. Trees 20 to 30 in trunk diameter were assigned a 25 diameter drip line target-symbol in a successively lighter shade of green. Finally, trees 20 inches and smaller in trunk diameter were assigned a 15 drip line diameter target-symbol in pale yellow. It should be noted that no individual tree inventory was included in the scope of this study, and the database used was made available by Denver Water as a significant contribution to the study. That being said, the database provided was only partially complete. There was no reference to species or condition in the inventory, and the trees were located but never sized from East Williamette Lane on Plan Sheet No.16 north. What the inventory shows is a fairly uniform distribution of different size/younger generation trees with larger gaps between the largest first generation trees represented. A representative section of the canal adjacent to Heritage High School was selected as a typical condition, and increased in scale from 1 = 300 to 1 = 150 to illustrate the evolution of the gallery forest into the future through a successive set of plan sheet projections. An additional set of plan sheets was developed to illustrate the impact of Denver Water Board-approved infill planting depicting a set of alternative plan view planting strategies, as well as sections of a future canal with the reforestation effort advanced. SECTION NO.6 SUSTAINABILITY ANALYSIS: The purpose of the sustainability analysis was to explore ways to provide establishment and maintenance water for infill tree planting, located along the shoulder of the trail on the opposite side from the canal channel. Considerations: Mature tree maintenance water requirements vary considerably from newly planted tree establishment and maintenance water requirements. SECTION NO.7 SIGNAGE IMPROVEMENT AND STANDARDIZATION ANALYSIS: The High Line Canal signage improvement and standardization analysis was undertaken to evaluate the way-finding information available to trail users along the study corridor, and to identify ways to improve the information presented. This discussion necessarily begins with an exceptional and unique aspect of the High Line Canal, that being its very size. As it meanders along the contours from the southwest boundary to the northeast limit of the Denver metropolitan area, it passes through four counties and seven cities, all of which have individual design standards for trail signage, and all of which are interested in establishing and promoting their individual brands. As a consequence of this multi-jurisdictional fabric, with numerous agencies investing in and responsible for the maintenance of the canal trail through their own communities, we see a segmented and provincial approach to signage along the canal. As a consequence, virtually none of the signage along the canal trail recognizes the contribution of Denver Water in making its maintenance access road available to trail users for their pleasure and use. Most significantly, in a glaring omission, none of the signage along the High Line Canal Trail is specific to the High Line Canal. None of the signage shows the entire length of the system, and no-where is its rich and important historical legacy recognized or celebrated. 3

8 SECTION NO.8 OPPORTUNITY AND POSSIBILITY IMPLEMENTATION PROCESS STUDY: The purpose of the opportunity and possibility implementation process study is to formulate a strategy and develop a methodology that will facilitate the conversion of the projects identified in this Preservation and Enhancement Planning Study needs assessment into physical upgrades and improvements to the High Line Canal corridor. Projects that will upgrade and improve the existing trail and signage system throughout the study corridor, as well as Denver Water Board approved infill planting projects that will preserve and enhance the tree canopy along the canal corridor for future generations. The opportunity and possibility implementation process study is intended to identify the next step in the planning process for the preservation and enhancement of the High Line Canal. A next step which will build on the work of this Preservation and Enhancement Planning Study, and which will become a natural extension of this needs assessment providing a road map moving forward. One possible next step is the development of a master implementation and phasing plan that will establish a framework for decision making which will provide the organization and structure necessary for the evaluation and prioritization of the individual improvement projects identified in this Preservation and Enhancement Planning Study. PUBLIC PROCESS: After completion of the planning study, and submittal of a draft report, informational public presentations were scheduled to share the opportunities and possibilities identified in this planning study / needs assessment with the public. The first presentation was conducted at the Goodson Recreation Center, 6315 South University Boulevard, Centennial, Colorado on June 27, The second presentation was conducted at the Arapahoe County Hearing Room, 5334 S. Prince Street, Littleton, Colorado on August 7, The third presentation was conducted at Cherry Hills Village, September 12, 2012 for both the Cherry Hills Village and Greenwood Village City Councils. 4