Cherry Creek Major Drainageway Plan
Upstream of Cherry Creek Reservoir
Mile High Flood District, Cherry Creek Basin Water Quality Authority, Douglas County, Southeast Metro Stormwater Authority, Town of Parker
Introduction
Purpose
Cherry Creek upstream of Cherry Creek State Park is a natural resource “gem” in the southeastern portion of the Denver metropolitan area. The Creek’s flowing waters, multi-storied riparian vegetation, and wide floodplain corridor provide habitat for wildlife and an attraction for people who enjoy traversing its trails and wading in the sandy stream.
Since the last Major Drainageway Plan (MDP) was completed on Cherry Creek in 2004, numerous stream improvement projects have been constructed and the approaches to stream stabilization have continued to shift towards high-functioning, lower maintenance streams. The design of these streams considers channel shape, natural materials, and vegetation to spread high flows and dissipate energy, and seeks to reduce reliance on hard structures. As a result, these types of streams support local habitat and biodiversity, and reduce long-term maintenance costs. The approach to master planning has also shifted from an emphasis on specific improvements to a thorough assessment of stream condition and the development of an overarching vision to guide future projects. The main goals of this MDP update include:
- Assess the state of the Cherry Creek Corridor from the southern boundary of Cherry Creek State Park to the southern MHFD boundary, just south of Bayou Gulch Road in Unincorporated Douglas County.
- Create a vision for the future of the corridor.
- Provide recommendations to help guide further efforts within the corridor based on the corridor vision.
- Utilize GIS-based tools throughout the study to improve data accessibility and facilitate future updates to the plan.
StoryMap Contents
The methodology and results of this study are presented in four sections. A table of contents is provided below. The study information can be read sequentially, or you can jump to any of the sections by clicking on the headings in the ribbon above.
Assessment • Desktop Analysis and GIS Database • Site Reconnaissance and Key Observations • 360 o Photographs of Study Reach • Detailed Ratings for Each Element of Stream Function • Beaver Activity • Water Quality Regulations • Summary of Channel Corridor Assessment • Summary of Watershed Assessment
Additional information and links, including a glossary of terms, are available under Resources .
Stream Elements
Introduction to the Elements of Stream Function
Concurrent with this MDP, the MHFD has developed a new tool for assessing stream functions called the Urban Stream Assessment Procedure (USAP). The goal of the USAP is to provide a consistent methodology to assess stream physical conditions and associated community values, and identify and prioritize projects that help achieve high-functioning, lower maintenance streams (HFLMS). This in turn supports the mission and vision of the MHFD and their community partners.
The USAP focuses on five elements to assess stream functions: community values, hydrology, hydraulics, geomorphology, and vegetation. Due to the added emphasis on water quality within the Cherry Creek watershed, a sixth element – water quality – was included in the assessment. Like the USAP, this study developed a system to rate the functionality of each element (on a scale of 1 to 5) based on criteria tailored to the nature of the creek and the scale of the study. The rating criteria for each element consist of stream characteristics observable via desktop analysis or site reconnaissance. The criteria for each element are shown below, and are divided into positive and negative factors that would either raise or lower the rating value.
The community values element centers around the interaction of people with the stream corridor and is characterized by human impacts on the stream, both positive and negative, and the stream’s impacts on human interests.
The management goal of this element is to provide riverscapes that enhance populated areas and improve quality of life while performing essential stream and floodplain functions.
The hydrology element considers the flow regime (peak flow, volume, duration, frequency of runoff) and is characterized based on the amount of change in the flow regime due to urbanization as compared to the stream’s historic, predeveloped, or natural condition.
The management goal of this element is to minimize changes to the historic flow regime through land use planning, runoff reduction practices, and the effective application of full spectrum detention.
The hydraulics element concentrates on how flood velocities, depths, and shear stresses for high flow events (flood events between the 5-year and 100-year storm frequency) are conveyed through the channel corridor.
The management goal for this element is to ensure that the channel corridor is effectively and safely conveying the full spectrum of anticipated flows.
The geomorphology element highlights the character and form of the stream, especially in the active channel corridor, in regard to the transport of bankfull flows and sediment and the trend towards or away from a dynamically stable system.
The management goal for this element is to maintain or establish balance in the way water and sediment are conveyed by the stream, thereby minimizing the potential for large-scale degradation or aggradation.
The vegetation element evaluates the current state of the riparian and upland plant communities and how the quality of the vegetation varies across the watershed and stream corridor.
The management goal for this element is to provide streambank and floodplain stability, infiltration, filtering, and habitat through healthy establishment of upland and riparian vegetation.
The water quality element seeks to understand watershed and stream conditions affecting the physical, chemical and biological quality of streamflows and to identify measures to enhance water quality and stream health. Poor water quality can be observed in the form of turbid, "brown" water from high sediment loads, excessive algal blooms in streams and lakes from high levels of nutrients, health concerns from elevated levels of bacteria, odors, impaired aquatic life due to low oxygen levels, and associated impacts.
The management goal of this element is to reduce the contribution of pollutant loads through source control and treatment processes and to maintain streams in a healthy physical condition.
Assessment
The existing condition assessment for Cherry Creek has two main components: the channel corridor and the watershed. While most Major Drainageway Plans focus on the channel corridor, the added emphasis on water quality necessitated a look at the watershed as a whole to identify additional water quality-related considerations.
Desktop Analysis and GIS Database
Numerous data sources were reviewed to inform the assessment of the channel corridor and watershed. Navigate to the right using the arrows in the slideshow below to see different maps and images that were part of this desktop analysis. Explore the study reach through these interactive maps, or view any combination of layers in the compiled GIS Webmap database linked under Resources .
Site Reconnaissance and Key Observations
A critical component of the assessment effort was a site reconnaissance that provided an accurate “up-close” view of conditions along the Creek. The project team walked the 15-mile study reach over a four-day period in October and November 2020. Team members observed and documented parameters associated with the six elements of stream function.
Navigate to the right using the arrows in the slideshow below to explore key observations that were made over the course of the site reconnaissance.
360 Degree Photographs of Study Reach
A selection of 360-degree photos are included in the mini-tour below - click the compass symbol to the right of the tour window to reveal a plan view map showing photo locations and direction of view. Additional photos along the reach are available for viewing in the full tour, linked under Resources .
Cherry Creek MDP Storymap Tour
Detailed Rating for Each Element of Stream Function
Detailed ratings for each element can be seen along the creek centerline using the interactive map to the left. The ratings are based on the existing condition; in most cases, lower ratings indicate opportunity for improvement. However, in some areas, lower ratings may be driven by larger constraints such as private property, historic development or other adjacent infrastructure that limits improvement potential. Ratings along the reach are indicated by colored parallel lines presented in order (left to right) of the six elements:
Three example reaches are presented below to illustrate how the ratings for the six elements were determined and how they might be interpreted together. You can navigate to any reach in the interactive map to view the ratings at any point in the study reach. Click on the element lines to identify the element and see additional notes from the site reconnaissance.
Example Reach #1: Good Overall Rating
Station 234+00 to 262+00 This segment at 17-Mile House has generally high ratings, indicating little need for intervention at this time. Click on the rating button to isolate and unisolate that element.
++ Well used and maintained soft surface trails ++ Good canopy cover ++ Good proximity from trail to channel +/- Programmed elements (but only on one side of the channel) - - Little access to water - - Larger distance between channel and residential community
++ Moderate level of upstream development +/- Major tributary: Baldwin Gulch - - Development generally pre-dates full spectrum detention
++ Wide benches ++ Wide floodplain area allows flow to spread out ++ Good connection between channel invert and benches resulting in milder velocities +/- Constructed reach
++ Low bank heights ++ Great connection between channel invert and vegetated benches ++ Riffles provide vertical stability while allowing for dynamism
++ Wider riparian corridor ++ Good mix of species, higher diversity ++ Mix of herbaceous, willow, cottonwood - - Human activity impacting vegetation along channel in some areas - - Slight disconnection between channel and floodplain
++ Wide benches ++ Good connection longitudinally between grade control structures ++ Sandy soils promote infiltration ++ Stable, healthy vegetation
Example Reach #2: Mariginal Overall Rating
Station 876+00 to 912+00 This segment upstream of Scott Road has generally low ratings, indicating a need for improvement to multiple elements of stream function. Click on the rating button to isolate and unisolate that element.
+/- New trail segment with neighborhood development, but minimal connectivity to channel - - Area surrounded by new and future planned development (increased human pressure) - - No human connection outside of construction activities - - No canopy cover
++ Low level of upstream development ++ Future and current developments incorporate full spectrum detention +/- Major tributary: Bayou Gulch
- - Narrow benches - - Incised active channel
++ No evidence of recent erosion ++ Not degrading rapidly - - Narrow, straight active channel - - Degrading Reach - - Less connection to benches
+/- Isolated spots of desirable herbaceous wetland species (sedges) at channel +/- Few trees, mainly crack willow and Russian olive +/- Upland mainly consists of brome with spots of horsetail - - Willow dieback - - Very narrow riparian corridor - - Presence of weeds in areas disturbed by development - - Little connection to floodplain
+/- Sandy soil +/- Moderate vegetation - - Narrow benches - - Channel is moderately disconnected from benches
Example Reach #3: Mixed Ratings
Station 624+00 to 654+00 While the previous project in this constructed reach downstream of Hess Road helped lift hydraulics, geomorphology, and water quality, a more targeted recreation and vegetation enhancement project could be undertaken to further lift the community values and vegetation elements. Click on the rating button to isolate and unisolate that element, and click on the rating lines in the map to see the reasoning for each rating.
Beaver Activity
Across many of the stream elements, beaver activity impacted the condition of the channel and therefore the rating of the elements. Beavers are a dynamic presence that can positively or negatively impact the various elements in developed settings:
++ Beaver dams can create better connection from the channel to the riparian benches (hydraulics, geomorphology, vegetation, water quality) - - Dams are not permanent and could wash out or cause lateral channel migration in larger events (hydraulics, geomorphology, water quality) - - If woody vegetation is not robust enough to support their activity, beavers can decimate the woody plant community and take down valuable trees (community values, hydraulics, vegetation)
The presence of beavers should be considered in element ratings based on the context of the reach, with emphasis on additional monitoring to mitigate negative impacts. Beaver management actions, when desired, are subject to state and local regulations.
Water Quality Regulations
Under the Colorado Department of Public Health and Environment, the Water Quality Control Commission develops water quality policy in Colorado. Several regulations directly relate to water quality in the Cherry Creek watershed.
Regulation 38: Classifications and Numeric Standards for South Platte River Basin
This regulation establishes beneficial uses and stream standards for Cherry Creek Segment 1, which spans from the confluence of East and West Cherry Creeks (11 miles upstream of the MHFD boundary) to the inlet of Cherry Creek Reservoir. Beneficial uses include Aquatic Life, Recreation, Water Supply, and Agriculture.
Regulation 93: Colorado’s Section 303(d) List of Impaired Waters and Monitoring and Evaluation List
Cherry Creek is listed as impaired for dissolved manganese and is on Colorado’s Monitoring and Evaluation List for E. coli. Additionally, the creek exceeds Colorado’s “interim values” established for total phosphorus (0.17 mg/L) and total nitrogen (2.01 mg/L), although these interim values are not yet adopted as standards for Cherry Creek. Cherry Creek Reservoir is currently listed as impaired for chlorophyll-a and dissolved oxygen. Water quality data considered for evaluation of Cherry Creek as part of the 303(d) listing process include samples collected by the Cherry Creek Basin Water Quality Authority, the Colorado Water Quality Control Division, Parker Water and Sanitation District, and River Watch.
Regulation 72: Cherry Creek Reservoir Control Regulation
Under this regulation, the watershed is subject to additional controls intended to manage nutrient loading, particularly phosphorus, to Cherry Creek Reservoir. These controls place additional requirements on the local jurisdictions to manage nutrients within the watershed. As the agency that helps coordinate and oversee nutrient management within the watershed, the CCBWQA developed a watershed-wide nutrient model to predict nutrient loading and transport by both surface water and groundwater within the watershed. The model considered baseline and future (2030) timeframes, accounting for development and stream stabilization efforts that are anticipated during the study timeframe.
See the Resources section for links to additional information about the watershed model, the CCBWQA, and the Water Quality Regulations listed above.
Summary of Channel Corridor Assessment
The majority of the study reach is in generally good condition, with some natural reaches, especially in upstream areas, exhibiting high function across many of the six elements. Thanks to effective stream rehabilitation improvements initiated by local governments and agencies involved in this study, a significant portion of the study reach has been stabilized through constructed projects that are also restoring a high level of functionality.
These stable reaches help protect water quality by limiting the amount of eroded sediment and associated phosphorus (a harmful nutrient in Cherry Creek Reservoir) that is carried downstream toward the reservoir, particularly during storm events. Where the active stream channel is shallow and closely connected to adjacent well-vegetated floodplain benches, treatment processes are also improving water quality via filtering, sediment capture, and infiltration as high flows spread out on the benches. Additional filtering and sediment capture occurs in the areas with multi-thread wetland channels due to the dense stands of wetland grasses in the channel.
Isolated locations of impaired reaches are experiencing varying levels of channel incision that adversely impact the hydraulic, geomorphology, vegetation, and water quality elements. The actively eroding degraded channels observed primarily in the downstream end of the study reach are likely major sources of sediment and associated phosphorus loads in Cherry Creek Reservoir. In addition, select locations where the community values element scored fairly low indicate opportunities for improvement.
Some reaches of Cherry Creek are dry; this may be associated with well withdrawals, subsurface hydrogeology, or sandy bed conditions with particularly high infiltration rates. In other areas, effluent discharges supplement base flows and are associated with dense wetland vegetation in the reaches downstream.
Summary of Watershed Assessment
Because activities in the upstream watershed affect conditions along Cherry Creek and in Cherry Creek Reservoir, this MDP was expanded to include a broad-level assessment of the watershed. This was based on a review of existing stormwater master plans in tributary watersheds, interviews with local jurisdiction representatives, projections of future development, and observations of features such as stock ponds and dams that might affect one or more of the six elements influencing stream function.
There is significant development underway or anticipated within the watershed. All jurisdictions have adopted full spectrum detention into their water quality criteria, which will help reduce the impacts of future development on stream stability and water quality. Local governments have also made sizeable land acquisitions aimed at limiting development by preserving open space areas; these lands enhance community values by setting aside natural areas that preserve habitat for wildlife, historic and cultural education opportunities, scenic viewsheds, and trail networks for the enjoyment of the public.
Stormwater criteria that were in place at the time existing developments were constructed vary between flood detention only, water quality capture volume, and full spectrum detention. Water quality requirements began to be implemented between 2000 and 2014.
Most local governments within the watershed are pursuing capital improvement projects for both stream stabilization and detention retrofits to improve water quality, and several master planning updates are on the horizon. Other programs being implemented within the watershed include water conservation efforts, source control measures such as household hazardous waste collection and street sweeping, and construction erosion control.
Vision
Illustrations of Functional versus Degraded Cross Sections
Typical Healthy Conditions Healthy sections of Cherry Creek exhibit consistent characteristics throughout the study reach, including:
- Shallow, stable active channel that allows high flows to spread out on adjacent overbanks
- Wide floodplain benches, well connected to groundwater
- Healthy multi-storied riparian vegetation, including native grasses, willows, shrubs, and trees
- Trail network along the overbanks
Typical Incised Conditions
Impaired sections of Cherry Creek were observed in three degrees of channel incision, illustrated by the cross sections below; a dotted line has been added to indicate the departure from a healthy section.
Case 1
Moderate downcutting of the active channel, creating disconnection between the active channel and floodplain benches and die-off of riparian vegetation adjacent to the active channel. Good quality vegetation remains in the overbanks, and is minimally impacted by channel downcutting.
Case 2
Downcutting of the active channel combined with accumulating sediment deposition in the adjacent vegetated overbanks that further deepens and disconnects the active channel from its floodplain. Overbank vegetation is of lesser quality, or is sufficiently impacted by sediment deposition and/or channel downcutting that it provides limited value.
Case 3
Massive bed and bank erosion along the active channel, creating a wide and deep canyon that is completely disconnected from the overbanks. This results in concentrated flows with high velocities, in turn creating high sediment and associated phosphorus loads being transported downstream. Vegetation in the high overbank terraces is severely impacted by the channel degradation, with widespread die-off due to dry conditions. Public infrastructure such as buried utilities, trails, or other facilities may be at risk due to the severe degradation.
Influence of Incision on groundwater and vegetation
Channel incision has a direct negative impact on the groundwater table. During base flow conditions, the groundwater table lowers with the lowered active channel. During moderate storms, the incised channel reduces the frequency and extent that flows spread out on overbanks and recharge/raise the water table. Vegetation in floodplain benches and overbanks dries out as a result of the disconnection between the lowered groundwater table and the plant root structure. The strength of the flood corridor weakens due to die off of vegetation, leaving bare sandy floodplain benches exposed to erosion during the more extreme flood events that are large enough to spill out of the incised channel. Concentrated flow conditions in the incised channel result in higher velocities and increased levels of erosion along the active channel bed and banks. Increased levels of erosion in the active channel and exposed floodplain benches increase sediment loads and associated phosphorus and other contaminants being transported to downstream waters and Cherry Creek Reservoir.
Proposed Streamscapes
Improvements to Creek Cross Section The overarching vision for Cherry Creek is to preserve healthy functioning reaches of the corridor and to restore impaired reaches to replicate the functional characteristics of the healthy reference reaches observed along the Creek, illustrated in the section below.
Depending on the level of degradation being experienced by Cherry Creek, three types of improvements are recommended to attain a healthy streamscape and the desired corridor function.
Case 1: Proactive rehabilitation measures
For reaches of Cherry Creek where the active channel is in the early stages of downcutting and adjacent overbanks still contain valuable vegetation and high community value, lower impact improvements can be implemented. These improvements may consist of raising the active channel invert to within two to three feet of the adjacent floodplain benches, minor reshaping of the active channel to geomorphically appropriate planform and cross section dimensions, and stabilization of the active channel with low height riffle structures and bioengineered bank protection. The remainder of the corridor may not need to be disturbed but will be revitalized by the raised groundwater table.
This type of improvement requires monitoring the extent of channel downcutting and proactive planning and implementation of restoration improvements, but results in minimal disturbance to the overall corridor and lower costs.
Case 2: Moderate rehabilitation measures
For reaches of Cherry Creek where the active channel is in early to moderate stages of downcutting and the adjacent overbanks may have accumulated sediment or do not contain much in the way of valuable vegetation or high community value, then more moderate levels of improvements may need to be considered. These improvements may consist of similar measures as the Type 1 improvements to raise, reshape, and stabilize the active channel. However, in addition, consideration can be given to lowering and/or regrading of the adjacent overbanks to form new floodplain benches that are well-connected to the active channel.
This type of improvement can offset the level of effort and cost of the active channel improvements, mitigate floodplain impacts caused by raising the active channel invert, and generate fill material for required fills within the project. Removal of some healthy vegetation may be required, and additional effort and cost will likely be needed to revegetate the newly graded floodplain benches with riparian plant life.
Case 3: Major rehabilitation measures
For reaches of Cherry Creek where the active channel has already experienced severe downcutting and erosion, and vegetation in the overbank areas has already died off due to the lowered groundwater table, then more extensive improvements will be required. These improvements may consist of a combination of filling the eroded channel and lowering of adjacent overbanks to form floodplain benches as well as shaping and stabilizing of the active channel within the new floodplain benches.
This type of improvement is more costly than the other types due to increased earthwork, overbank protection, and significant revegetation efforts. However, a successful restored corridor can still be achieved over time.
Beneficial Effects of Creek Improvements on Groundwater and Vegetation
Restoration of the impaired reaches to a healthy streamscape will provide benefits to groundwater and vegetation during both baseflow and stormflow conditions. For baseflow and minor stormflow conditions, a shallow active channel will keep the groundwater table within reach of the root system of riparian vegetation on floodplain benches, keeping this vegetation healthy and able to provide erosion protection and water quality benefits.
Well activity can influence the groundwater table, creating some disconnection between vegetation and groundwater. These influences are typically localized to within the vicinity of the well fields.
When stormflows exceed the capacity of the active channel during moderate storm events, a healthy streamscape will allow stormflows to spread into wide floodplain benches, yielding lower flow depths and lower velocities and reducing erosion potential. In addition, stormflows out on wide floodplain benches will allow for additional infiltration and vegetative filtering, which further hydrates plants, benefits water quality, and helps to reduce flood peaks downstream.
Water Quality Considerations Although this Master Plan does not provide a detailed evaluation of water quality, assessment of water quality data under Regulation 93 provides useful context for establishing a water quality connection for stream master planning efforts. For example, channel reclamation activities that help reduce sediment loading – by stabilizing eroding banks and filtering and infiltrating storm runoff in vegetated floodplain benches -- can also reduce phosphorus loading to Cherry Creek Reservoir, which can in turn help to reduce chlorophyll-a concentrations. Bringing stormwater in contact with soil and vegetation to reduce the volume and frequency of runoff in developing areas of the watershed can reduce storm-generated pollutant loads. Additionally, trail planning and educational signage related to picking up pet waste can be important tools in reducing E. coli loading to Cherry Creek. Stream reclamation activities are not expected to have a strong linkage to dissolved manganese load reduction; however, evaluation of dissolved manganese sources was beyond the scope of this plan.
Improvements to Community Engagement In addition to improving the creek cross section to provide better hydraulic, geomorphic, and water quality function, there are also opportunities to improve community engagement within the Cherry Creek corridor. The level of improvement depends on the level of engagement desired. Examples of possible improvements ranging from lower levels of engagement to higher levels of engagement are shown below; navigate to the right using the arrows to see various levels.
Recommendations
Prioritization of Stream Improvements
Channel segments were evaluated based on the current stream assessment ratings and the potential for improvement, or lift, to each element of stream function. The lift indicates the difference between the existing rating and the potential improved rating. This information was tabulated and color coded - Using the arrows, navigate to the right through the images below for a description of the table fields and colors. A link to the full table is included in the Resources section.
Channel Rating Scale: Poor - Marginal - Fair - Good - Excellent
Nineteen reaches with potential lift were identified. Note that many "potential improved ratings" are less than 5 - many channel segments have constraints that limit the potential rating for various elements. Because the hydrology rating is dominated by the upstream watershed, no lift is shown in association with any recommended improvement areas. Outside of the nineteen sites, 47% of the study reach has no recommendations at this time. These areas have already been stabilized, have reached a stable state, or are constrained such that additional lift is not practial. The breakdown of priority reach length is shown in the figure below.
The following map tour identifies the nineteen sites in order from downstream to upstream along the study reach, listing the priority, recommended action and associated rating improvements at each site. The existing ratings are indicated by the element rating lines in the map.
1
Upstream of Piney Creek Confluence Station 30+00 to 38+00 Action: Stabilize active channel, improve connection to overbanks, enhance vegetative cover, consider coordinating with golf course on modifying the existing frisbee golf course to increase usability and direct visitors away from areas with higher erosion potential.
2
Downstream of Arapahoe Road Station 52+00 to 73+00 Action: Stabilize active channel, improve connection to overbanks, and enhance vegetative cover. Include consideration of golf playability and safety, and protection of water and wastewater infastructure (Aurora wells and lift station).
3
Upstream of Arapahoe Road I Station 76+00 to 110+00 Action: Stabilize active channel, improve connection to overbanks, enhance vegetative cover.
4
Upstream of Arapahoe Road II Station 112+00 to 146+00 Action: Enhance desirable vegetative cover through reseeding with drought tolerant species and weed management.
5
Parker Jordan Open Space Station 196+00 to 232+00 Action: Add intermittent riffles to mitigate potential undermining of grouted boulder drops.
6
Downstream of Cottonwood Drive Station 285+00 to 302+00 Action: Enhance upland vegetation using a targeted approach revegetating areas with minimal coverage and evidence of instability with drought tolerant upland species and weed management.
7
Upstream of Cottonwood Drive Station 314+00 to 334+00 Action: Stabilize active channel, improve connection to overbanks, enhance vegetative cover, improve access to stream.
8
Downstream of E-470 Station 336+00 to 354+00 Action: Consider incorporating trail access to channel. This location is also ideal for incorporating bird and wildlife watching enhancements.
9
Pine Lane to E-470 Station 360+00 to 380+00 Action: Stabilize active channel, improve connection to overbanks, enhance vegetative cover.
10
Downstream of Lincoln Ave Station 400+00 to 426+00 Action: Stabilize active channel, improve connection to overbanks, enhance vegetative cover. Formalize soft surface trails and connection to channel, ideal location for nature play enhancements. Mitigate safety concerns surrounding exposed concrete pipe sections and erosion caused by human activity, increase visibility into corridor to deter undesirable activity.
11
Dransfeldt Road (extended) Station 552+00 to 584+00 Action: Stabilize active channel, improve connection to overbanks, enhance vegetative cover, add trail crossing and realign trail.
12
Downstream of Hess Road I Station 609+00 to 624+00 Action: Add intermittent riffles to mitigate potential undermining of sculpted concrete drops, supplemental planting, enhance community value.
13
Downstream of Hess Road II Station 624+00 to 652+00 Action: Formalize desired soft surface trails and reclaim excess social trails to promote access to concrete drop structures and prevent erosion. Plant canopy trees along trails for shade.
14
Upstream of Hess Road Station 655+00 to 669+00 Action: Assess and possibly mitigate beaver activity.
15
Downstream of Stroh Road Station 680+00 to 718+00 Action: Possibly add intermittent riffles between existing riffles to reduce drop height of existing riffles.
16
Hungry Horse Open Space Station 800+00 to 844+00 Action: Stabilize active channel, widen riparian benches, improve connection to overbanks, enhance vegetative cover. Consider adding trail access to channel. Monitor vegetation and consider targeted revegetation with drought tolerant upland species.
17
Downstream of Scott Road Station 854+00 to 876+00 Action: Community values has a low score due to private property and no public access to corridor. Only list as priority area if consideration of easement acquisition or Right of Way is viable/desirable. Currently only available community value enhancements would be trash and debris removal.
18
Upstream of Scott Road Station 878+00 to 920+00 Action: Stabilize active channel, improve connection to overbanks, enhance vegetative cover, add trail connection to channel and increase tree canopy along trails for shade.
19
Bayou Gulch Road Station 940+00 to 964+00 Action: Increase trail connectivity to surrounding neighborhoods. Increase visibility from trail to channel. Increase canopy tree cover for shade along trail. Add trail connection to channel.
Watershed Management Recommendations
With an eye toward managing stormwater and enhancing water quality further upstream in the watershed, before flows reach Cherry Creek, additional recommendations have been formulated based on the findings of the watershed assessment. The recommendations below are both general, applying to the whole watershed, and specific, summarized by region.
General Watershed Recommendations An overarching recommendation is to manage watershed hydrology to levels similar to undeveloped conditions. This objective is aimed at reducing destabilizing stresses on tributary streams and the Cherry Creek mainstem and limiting the increase in stormwater peaks, volume, frequency and duration from urbanization with their associated phosphorus, other nutrient, and sediment loading. Strategies for achieving this objective include:
- Implementing runoff reduction measures such as grass swales and buffers in newly developing areas for increased infiltration and filtering of runoff.
- Laying out future developments to preserve or recreate fine stream networks reaching upstream beyond the traditional 130 acre major drainageways (a dendritic approach). These extended stream networks, if vegetated and stable, provide opportunities to filter, infiltrate, and slow runoff.
- Implementing full spectrum detention in a distributed manner to treat developed flows prior to entering the stream network, if possible, to reduce stream impacts.
- Retrofitting full spectrum detention and runoff reduction features in areas developed prior to full spectrum detention and water quality criteria.
Another general recommendation for tributary watersheds is to follow the stream reclamation template created for McMurdo Gulch. This template promotes regular observations of stream conditions and a proactive approach to address “hot spots” of initial instability before they progress significantly. The McMurdo Gulch template can be found under Resources .
Regional Watershed Recommendations Since conditions within the Cherry Creek watershed vary geographically from upstream to downstream and from west to east, the following paragraphs provide specific recommendations by region. The geographic boundaries of these regions are depicted on the MDP mapping.
Far Upper Watershed
This region is primarily agricultural with some small pockets of large lot development and no known areas of planned future development. Numerous dams constructed in the 1960’s by the Soil Conservation Service (SCS) are currently managed by Douglas County and the Douglas County Conservation District.
Recommendations:
- Consider partnering with the Douglas County Conservation District on potential projects to preserve or retrofit water quality features in existing dams, and to provide additional informational resources on water quality management for agricultural activities within the Cherry Creek watershed.
Upper Watershed - West
This region is currently very active with development projects and, with the Looking Glass and Tanterra communities, is at the forefront of the recent shift to Development Improvement Projects (DIP), where the MHFD partners with local governments and developers to promote development techniques which maximize stormwater benefit through practices like dendritic design and distributed detention. Steep terrain necessitates specialized approaches to development and stream stabilization. Previous development in the Founders Village area of Castle Rock pre-dates water quality requirements.
Recommendations:
- Update older master plans: Mitchell Gulch (2006) and Scott Gulch (2006)
- Include historic flows in hydrologic analysis as a target for master planned improvements to attenuate future development flows to be at or below historic levels
- Preserve existing stream networks and promote dendritic design; implement distributed detention to reduce future development flows prior to entering stream network
- Promote offline controls to manage stormwater quality and quantity on the higher terrain before it reaches the stream valleys
- Continue with current program of water quality retrofits in Founders Village
Upper Watershed – East
This region currently has little to no development activity. Portions of Timbers Creek are in need of stabilization. The Pinery development pre-dates water quality requirements.
Recommendations:
- Continue stream stabilization efforts along Timbers Creek – a steep, sandy, erosive stream – following the successful recent pilot project
- Monitor Bayou Gulch downstream of the confluence with Timbers Creek for impacts of erosion on Timbers Creek and of development adjacent to Bayou Gulch
- Continue with current program of water quality retrofits in the Pinery
- Consider updating master plans to help guide water quality retrofits
Upper Watershed – Direct Flow Areas
This region was included in the Kinney Creek / Fonder Draw master plan. Active developments are meeting current detention and water quality requirements.
Recommendations:
- Look for opportunities to improve minor tributary channels downstream of developments, within the overbanks of Cherry Creek, with the same approach as Cherry Creek improvements: shallow, stable active channel that spreads higher flows over floodplain benches. Decrease channel slopes by adding stream length: utilize wide Cherry Creek corridor to create meandering tributary channel alignment. This approach maximizes the stream's natural and beneficial functions, which in turn improves water quality.
Middle Watershed – West
Future development in this region includes a large master-planned community as well as smaller development areas. Master plans promote full spectrum detention, and numerous projects are in the works to address channel stability concerns.
Recommendations:
- Continue stabilization efforts along both Happy Canyon Creek and Newlin Gulch
- Partner with developer via MHFD DIP program to protect and stabilize Badger Gulch in Ridgegate development area
- Consider partnering with the Castle Pines North Metro District to retrofit existing regional detention ponds for full spectrum detention; the improvements may need to be paired with stream stabilization in downstream channels if the combination of increased stormwater volume from upstream development and reduced sediment loading as a result of online detention leads to degradation
Middle Watershed – East
This region is nearly built out, but has some potential for future development along the upper portion of Tallman Gulch. Some of the denser developed areas near downtown Parker pre-date water quality requirements.
Recommendations:
- Update the Sulphur/Tallman/Sara gulch master plan (2001)
- Look for opportunities for water quality or full spectrum detention retrofits
Middle Watershed – Direct Flow Areas
This region is also nearly built out, with some older developments that may pre-date water quality requirements.
Recommendations:
- Update master plans
- Look for opportunities for water quality or full spectrum detention retrofits
- Look for opportunities to improve minor tributary channels downstream of developments, within the overbanks of Cherry Creek
Lower Watershed
Sizeable developments are on the horizon in Aurora and Douglas County in the eastern portion of the watershed, with some smaller infill areas along the mainstem and western tributaries. A master plan update of the minor tributaries is in progress as of the publication date of this study; any recommendations for those areas will be included in that update. The western tributaries include regional water quality but little pre-treatment; the Piney Creek tributary to the east includes regional detention but not water quality.
Recommendations:
- Continue implementing master plan improvements, including retrofits of existing detention facilities
- Consider developing a master plan for the direct flow area in Douglas County
- Look for opportunities for water quality or full spectrum detention retrofits
- Look for opportunities to improve minor tributary channels downstream of developments, within the overbanks of Cherry Creek
- Consider converting channels with concrete trickle channels to vegetated channels in order to reduce the frequency of maintenance and promote natural stream functions such as infiltration and filtering
Monitoring Plan Development
The assessment and recommendations discussed in this plan are based on observations that were made in 2020. With continual activity and development within the watershed and the dynamic nature of the channel system, the condition of Cherry Creek will continue to change over time. To help manage the creek into the future, an active monitoring plan should be created. Potential goals of the monitoring plan include the following:
- Track the condition of Cherry Creek over time
- Proactively identify problem areas before they become bigger issues
- Assess the performance of improved reaches
- Update improvement prioritization to help inform Capital Improvement Plans for local jurisdictions
- Keep this Cherry Creek MDP up to date
Because the Cherry Creek watershed covers a multitude of jurisdictions, implementation and management of the monitoring plan would optimally to be a shared responsibility. An Intergovernmental Agreement (IGA) executed between vested stakeholders including MHFD, CCBWQA, SEMSWA, City of Aurora, Town of Parker, Town of Castle Rock, Arapahoe County, and Douglas County could provide the mechanism for ongoing monitoring of Cherry Creek. The IGA should specify monitoring activities, frequencies, and reporting methods. Recommendations for these items are listed below for consideration by participating agencies.
- Full site walks
- Conduct a field reconnaissance of the Cherry Creek corridor for the entire 15-mile study reach.
- Frequency: every four years
- Targeted site visits
- Inspect specific areas of concern defined by previous assessments, damage caused by storm events, or otherwise brought to the attention of the local jurisdictions.
- Inspect newly constructed improvements within the corridor.
- Frequency: every one to three years, subject to storm events or completed construction projects.
- Check in with local jurisdiction representatives
- Gain updates on new development or land-use changes, upcoming or completed stream restoration projects along Cherry Creek or tributaries, and new or retrofitted regional detention and/or water quality facilities.
- Frequency: every two years
- Reporting/Data Management
- Utilize standard monitoring forms for field data collection and check-in documentation to ensure consistency from occurrence to occurrence. Examples of these forms are provided in the Resources section of this study.
- Compile data from monitoring activities in a GIS database. Show updated ratings and prioritization on new layers for each occurrence to allow comparisons with previous years.
- Prepare a summary report to accompany updates to the GIS database for each round of monitoring.
Resources
Follow the links below for additional information:
Documents Glossary of Terms References Priority Area Table (.pdf) Priority Area Table (.xls) Sample Monitoring Report and Forms Web Map and GIS Data Link: Cherry Creek Major Drainageway Plan Web Map Download: Web Map Geodatabase Download: Historical Imagery (georeferenced in GIS) 360-degree Photo Tour Link: Expanded Photo Tour - Host website temporarily down Document: Photo Tour Navigation Tips Construction Plans for Completed Projects along Cherry Creek Tributary Streams - Master Plans and Studies MHFD HFLMs & USAP Links Website: High-Functioning Lower-Maintenance Stream Framework Video: Stream Management Academy Video: An Introduction to High Functioning & Low Maintenance Streams Video: High Functioning Low Maintenance Stream Framework
Water Quality Links Cherry Creek Basin Water Quality Authority Regulation 38: Classifications and Numeric Standards for South Platte River Basin Regulation 93: Colorado's Section 303(d) List of Impaired Waters and Monitoring and Evaluation List Regulation 72: Cherry Creek Reservoir Control Regulation
