behind the scenes of this golfing masterpiece lies the expertise of snyder & associates, as our team played a pivotal role in shaping the topography, managing water resources, and ensuring environmental compliance for tpc wisconsin.

nurturing environmental commitment

the foundation of any successful golf course lies in a thorough understanding of the existing topography and layout. our team of skilled surveyors conducted a topographic survey of the current key features, which included the waterways, ponds, and wetland areas. the bathymetric survey, or mapping of the natural contours underwater, was done by a boat drone and manually with kayaks. this detailed assessment provided the designers and developers at tpc wisconsin with crucial information to optimize the course layout, creating a challenging yet harmonious golfing experience.

this spurred the journey to begin with an environmental perspective, as the area earmarked for transformation was once a marsh filled with silt. the restoration project became an opportunity to create a top-tier golf course and revive over 35 acres of degraded wetlands linked to the cherokee marsh. the removal of silt and the revival of the wetlands have dramatically increased the stormwater quality of water meandering through the golf course system.

tpc wisconsin design evolution

steve stricker, intimately involved in the design process, embarked on a nationwide exploration to understand the nuances of professional golf course design. after examination, the decision was clear: the course needed elevation, vegetation removal, and the restoration of canals and waterways to their original functionality.

navigating water features seamlessly is essential for golfers; all water crossings facilitate this. snyder & associates employed their engineering ability to design efficient culverts. they planned bridge locations that not only enhanced the aesthetic appeal of the course but also ensured the smooth flow of water, mitigating the risk of flooding and erosion.

the original golf course featured numerous perched culverts, where the inlets were positioned higher than the water level, posing a challenge for water and aquatic life to move freely between waterways. with the introduction of the new course design, several enhancements were implemented to address this issue. a total of six bridges were constructed, replacing some of the problematic culverts, while other culverts were strategically lowered within the water level to facilitate the movement of wildlife. additionally, the culvert diameters were expanded in many areas to promote smoother water flow, contributing to a more ecologically friendly and interconnected environment.

the challenge of drainage

snyder & associates are conducting a hydrologic survey at tpc wisconsin.

a pivotal focus during the design phase was drainage, as wisconsin’s landscapes are characterized by diverse water bodies, necessitating a robust hydrological strategy. our experts conducted thorough hydrological studies to understand water movement patterns, prevent any rise in the elevation of the floodplain post-construction of the golf course, and ensure that the overall design harmonized with the natural flow.

while elevating fairways, greens, and tees was part of the design, it necessitated a thoughtful balance to avoid adverse effects. strategic cuts were made in other sections throughout the course to offset these filled areas. additionally, waterways underwent enlargement and dredging initiatives, fostering improved water flow and habitat for wildlife. the process was meticulously modeled to abide by floodplain management rules and regulations.

furthermore, the team took proactive measures to secure the essential floodplain permits required for the project’s execution. this involved engaging with regulatory authorities and presenting a detailed report that adheres to environmental standards and floodplain management guidelines. by obtaining the necessary permits, the team ensured compliance with local regulations, fostering a collaborative relationship with regulatory bodies and affirming the project’s commitment to responsible development and environmental stewardship.

project completion: wrapping up the final details

within an 8-10 week grassing window, the course was entirely rerouted, re-grassed, and equipped with a new irrigation system. the result is a meticulously crafted golfing paradise, ready to host the pga tour champions american family insurance championship from 2025 onward. spectator mounding adds to the allure, promising an unforgettable experience for golf enthusiasts and casual spectators.

dennis tiziani’s vision for tpc wisconsin goes beyond creating a world-class golf course; it’s about revitalizing the landscape, fostering environmental sustainability, and catalyzing positive change in the community. as the greens of tpc wisconsin welcome players and spectators, it stands as a testament to the transformative power of collaboration, innovation, and a commitment to excellence in every aspect of the golfing experience.

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beyond wetlands, creating new amenities in wanatee park

during the initial design stages, community leaders had the sole intention of creating new wetlands within the park. while conducting site inspections, our environmental team noticed a few additional improvements that would significantly benefit park amenities while also enhancing water quality within the local watershed. through discussions with linn county conservation officials, a new trail bridge and fishpond were approved in addition to the planned wetlands.

wetland creation & enhancements lead design efforts

in total, seven wetlands were constructed or rehabilitated to increase the park’s sustainability and improve the area’s water quality.

our project team focused on the wetlands portion of the project first. county officials already had specific areas in mind for potential wetland enhancement and creation. throughout these assessments, our team vetted the options, affirming their selections and providing new suggestions, as well. in total, seven sites were chosen for wetland improvements, with a net cut of 2,280 cubic yards achieved.

though all wetland sites required updates, there was a varying degree of work needed across the seven locations. some of the wetlands were enhancement projects where the area had once been deeper but had filled in with sediment over time. for these areas, the focus was excavating sediment and restoring hydrology to improve wetland functions and provide an environmental lift.

other wetlands were created from scratch based on the location of drainage features and tiles. agricultural tiling systems previously conveyed water from nearby fields into wanatee creek. a few of the newly constructed wetlands allowed tiles to flow openly within the wetlands, supplying hydrology and creating ideal wetland habitats. this was a great way to improve water quality as tiles that had previously outlet nutrients directly into the creek now drain into the wetlands and the nutrients are absorbed by plants rather than flowing downstream. several of these constructed wetlands included an agri drain water level control structure™ in the designs. these structures allow linn county conservation staff to draw down wetland water levels if necessary, for seeding or vegetation maintenance, such as treating invasive species.

consistent with the water and land legacy bond’s initial goal, these wetlands filter nutrients and provide floodplain storage benefits necessary to improve local water quality while enhancing wildlife habitat and the natural beauty of the surrounding landscape.

pedestrian trail bridge replaces high-maintenance culverts

the new bridge sits higher than its predecessor to avoid washout potential.

the next phase of this project focused on the construction of a 30-foot-long prefabricated steel truss pedestrian and maintenance bridge over wanatee creek. this bridge was designed to replace deteriorated twin corrugated metal pipe (cmp) culverts that were past their useful life. the culverts were covered by a soil and mulch mixture that would constantly be washed out and require replacement due to the low trail profile and the crossing’s location in the federal emergency management agency (fema) regulatory floodway.

a more permanent structure at a higher elevation was necessary. our team consulted with our structural subsidiary, shuck britson, to identify design solutions. it was determined that using a prefabricated structure with site-specific dimensions would be the best fit as these are well suited for similar span lengths and trail bridge loading. because this is a fairly simple design that requires no formwork or falsework, this option ended up being the most economical solution for the client, as well. the bridge was assembled off-site by the manufacturer and shipped to the park for placement. a crane was used to lift the approximately 20,000-pound bridge off the truck and position it on the newly designed and constructed abutments.

since this crossing is also the main access point for county maintenance vehicles, special consideration was taken during its design. to accommodate vehicle access across the bridge, the connecting trail had to be built at a different slope than the pre-existing crossing to allow for a wider trail radius. this also created an opportunity to perform 100 feet of stream restoration to stabilize the channel flowing under the new bridge.

stream restoration efforts improve aquatic habitat

during the new trail bridge design process, scour issues were apparent in the section of wanatee creek surrounding the crossing and the banks lacked stabilization as they had previously only been shielded by bits of broken concrete. despite all of this, the creek in this location was in decent shape, however, the aesthetics did not match the surrounding prairie or park objectives. to stabilize the streambanks and enhance aesthetics, flexamat® erosion mats were used to defend against streambank erosion and promote native vegetative growth.

since wanatee creek experiences high velocity flows, additional flexamat® was installed across the bottom of the channel to further protect against scour associated with the new bridge. the result was an extremely smooth streambank transition that is hard armored, easy to maintain, and much more aesthetically pleasing than the bits of broken concrete that previously lined the banks. after a summer’s worth of vegetation growth through the flexamat®, the project has shown a major improvement in water quality, stream function, stabilization, and in-stream wildlife habitat, all while successfully complementing the park.

after completing the construction of the bridge and stream improvements, linn county conservation staff observed orange-throated darters near the new bridge, which hadn’t been spotted in this area in some time. this freshwater fish species is on iowa’s endangered list and its arrival was seen as a significant success by county leaders and staff.

creation of recreational fishing pond draws anglers

the pond helps sustain the area’s high water quality and is stocked with bluegill, bass, crappie, and other local species.

the final piece of this project involved the construction of the first fishable pond owned by linn county. the pre-existing site for the pond consisted of a bermed-up area that was weedy, non-functional, and underutilized as a wanatee park attraction.

specific elements were incorporated into the pond’s design to promote water quality and meet project goals, including a sediment forebay, shallow slopes, an impermeable clay base layer, and seepage mitigation measures such as drainage diaphragms. these features, along with native plantings and a recently added prairie buffer, help filter pollutants off the adjacent highway and farm fields and protect the pond as water enters. with a healthy pond system established, our environmental team equipped the pond with various items to enhance fish habitat, including spawning beds, jetties, and assorted depth pools.

the pond also included an agri drain water level control structure™, a cmp riser outfall, and an emergency spillway. our experts determined this was the best fit for the area as it enables staff to control water depths and maintain fishing structures. these additions, along with shallow slopes near the interior perimeter, increase safety for recreational users. county crews are responsible for continual maintenance and routinely mow a trail around the pond for improved access. after construction was completed, the pond was filled and stocked with bluegill, bass, crappie, and other local fish species.

collaboration & communication leads to project success

the success of these projects involved significant collaboration between the snyder & associates project team and linn county conservation officials. our experts helped with the technical aspects while the client attended site visits, discussed site conditions, and helped determine where the various project features would be placed. between their vision and our expert designs, wanatee park continues to experience improved water quality and is viewed as a blueprint for future collaborative efforts.

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the banks of fourmile creek are undergoing stabilization efforts utilizing rip-rap and vegetation.

the fourmile creek watershed in central iowa consists of nearly 80,000 acres of urban and agricultural communities. it’s also home to over 80,000 residents. as this population has grown over many decades, this expansive watershed has become increasingly prone to regular flood events.

these reoccurring floods have impacted numerous residents, resulting in frequent evacuations and the costly destruction of property. extensive efforts have been taken by several government agencies to minimize flooding and enhance the overall water quality in the watershed. a seasoned team of engineers and environmental scientists from snyder & associates has been at the forefront of these efforts since 2006. through a multitude of projects, our team has made a significant difference in the health and safety of this critical water system.

updating fourmile creek modeling & assessments

initially, snyder & associates was commissioned to study the fourmile creek watershed to establish an accurate floodplain model to update the significantly outdated federal emergency management agency (fema) maps. our team of environmental scientists and engineers used hydrologic and hydraulic flood models, along with stream assessments, to evaluate the impact of flooding on future development and the impact that development may have on the watershed.

hydrologic methods from previous studies only accounted for current land use while grouping the entire watershed into one basin. our team completed a comprehensive review of both existing and future land use plans to predict potential conditions in hydrologic models. each of these models divided the 118-square mile watershed into individual sectors to provide a more accurate analysis.

peak flow rates developed through modeling were used to predict fourmile creek’s response to flood events of varying magnitude and duration. a profile of the watershed patterns was established to create flood maps utilizing lidar data and arcgis software. these maps provide valuable information by increasing awareness of the likelihood of flooding and ultimately, reducing the devastating impacts floods can produce.

streambank stabilization increases watershed resilience

stream flooding in fourmile creek tributary a prior to stream stabilization improvements.

in addition to extreme flooding issues, fourmile creek has a long history of erosion and poor water quality. many factors, such as above-normal precipitation and runoff volumes, impervious surfaces, and agricultural practices within the watershed contribute to the stream’s degradation and erosion. specifically, two tributaries of the creek located in ankeny — northeast tributary a and southeast tributary b — experienced extensive stream degradation and bank erosion after the 2008 floods and placed many properties and infrastructure at risk.

to address these individual tributaries, our team assessed over 7,400-feet of the stream before proposing improvements that would not only mitigate flooding but also complement the stream’s natural protection, as well. this assessment, along with our intimate knowledge of the watershed, led to sustainable design solutions.

homeowner input, technical assessments, and an evaluation of alternatives were utilized to prepare conceptual designs for both tributaries using an integrated stream restoration approach. this approach provided cost-effective and aesthetic creek restoration through the combination of several techniques including vegetated buffers, toe protection, graded floodplain benches, and weirs. combined, approximately 6,500-linear-feet of the stream was successfully stabilized at the conclusion of both projects.

fourmile creek watershed management authority & stormwater management plan

while the rehabilitation of the two tributaries drastically improved the creek’s overall water quality, additional efforts were necessary to continue mitigating flooding, erosion, nutrient loading, and bacteria issues. to address these problems, local communities created the fourmile creek watershed management authority (fcwma) in 2012. this group focuses on collaborative work to address both flooding issues and water quality. snyder & associates was commissioned to study the region with the intent of improving the understanding of the watershed and preparing a stormwater management plan.

our experts knew that appropriate mitigation had to account for a powerful, meandering alluvial stream that transports significant sediment load. in some cases, extreme events caused substantial channel changes due to high flow, debris jams, erosion, and sediment deposition. toe rock protection integrated with bendway weirs, floodplain benches, and native vegetation buffers were incorporated into the design. additional measures included establishing permanent easements and expanding polk county’s adjacent conservation area which helped diversify stream habitat and increased wildlife access to the water.

this management plan also addresses overall maintenance goals and responsibilities, budgetary costs, and phasing for the full development of the comprehensive system. additionally, potential regulatory tools, grants, and funding opportunities were outlined and adopted by all jurisdictions involved.

fourmile creek greenway master plan

natural vegetation was incorporated during restoration to enhance wildlife ecosystems.

a series of eight watershed goals aimed at reducing flooding and improving water quality were included in the plan to provide guidance. each goal was assigned subgoals and tasks to help track milestones and develop a schedule. the adoption of a greenway system, or master plan, was one of the eight primary goals of the fcwma. this specific goal outlines practices, such as native vegetation re-establishment, stream restoration, and wetland enhancements. the greenway master plan addresses these improvements, as well as potential recreation and education opportunities along approximately 10-miles of the creek.

stakeholder input and thoughtful consideration of multiple elements are essential when 2022世界杯32强预选赛 and implementing a greenway system. during a 世界杯足球比赛预选赛 open house, our team gathered community input for the future of fourmile creek, which helped shape the plan’s objectives.

greenway master plan objectives:

• flood management and water quality
• native habitat protection and management
• define greenway
• make connections
• 世界杯足球比赛预选赛 access and service
• education
• economic development
• implementable steps

the greenway master plan provides a path to transform the current, developed landscape to a more natural state. to start, it’s necessary to move at-risk human life, property, and infrastructure away from the floodplain. in place of the developed landscape, work commenced establishing oxbow wetland connections, construction of a stormwater wetland, and prairie restoration. once completed, this corridor will provide many community benefits including recreation, alternative transportation, improved water quality, habitat conservation, and flood control.

stormwater wetland reduces nutrient overloads & flooding

as the greenway plan expanded, partners of the watershed project saw an opportunity to be proactive in developing a solution to protect the environmentally sensitive fourmile creek. this resulted in a stormwater wetland which once again brought our team on board to provide environmental and stormwater design services.

positioned adjacent to the popular gay lea wilson trail, the stormwater wetland provides a natural means to remove pollutants from stormwater and reduce overall flow rates. as stormwater is captured within the wetland, pollutants are removed naturally through reduced water velocity and increased settling, uptake, and filtering by vegetation.

volume control is a particularly important benefit as there are downstream portions of fourmile creek that have been restored and stabilized, but there are other locations that continue to suffer from severe bank erosion. managing the channel protection volume in the wetland improves overall stabilization efforts to reduce sediment transport.

the stormwater wetland helps to treat and slow down 23 acres of stormwater runoff from an adjacent suburban landscape before entering fourmile creek. improvements like this help to reduce sediment and pollutant loading into the des moines river further downstream, protecting it for years to come.

fourmile creek restoration gives new life to natural areas

for over 15 years, snyder & associates has helped shape implementation efforts across the fourmile creek watershed through both agricultural and urban areas. today, work on the fourmile creek watershed continues with stabilization improvements and 世界杯足球比赛预选赛 education outreach that teach residents how to better take care of our watersheds. the snyder & associates team stands ready to continue providing guidance for this beneficial and forward-looking endeavor.

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conservation and 世界杯足球比赛预选赛 safety don’t frequently coincide. across iowa, however, a growing movement to remove or modify dangerous and deteriorating low-head dams in rivers and streams are in full swing. the impact of this campaign aims to benefit both nature and the general 世界杯足球比赛预选赛 .

lenon mill dam, located on the middle raccoon river near panora, is one of those targeted structures. originally built from heavy timbers prior to the u.s. civil war, the structure underwent several renovations throughout the years as technology advanced. eventually, this resulted in a concrete cap being placed over the top and back face of the dam to protect the dam’s structural integrity.

after heavy rains fell across the watershed, the river rose almost seven feet in less than ten hours. during this major flood event a section of the concrete cap broke off, making the structure extremely vulnerable and susceptible to further damage in the near future. to head off catastrophic failure, panora city leaders turned to snyder & associates to come up with a short-term solution that could withstand high waters and be assembled rapidly — all while staying within the city’s funding limitations.

to make the situation more daunting, the middle raccoon river provides the city’s main water source and the damage to lenon mill dam produced a significant risk to their drinking water supply. if another flooding event were to occur before the damaged section was repaired, there was a real possibility of complete dam failure and loss of water supply.

natural rock used to reinforce dam structure

to avoid the dire scenario posed by a dam breach, our team proposed reinforcing the dam with a native stone structure sloping away from the dam’s downstream face. these stones would fill the area where the concrete cap broke loose and also strengthen the overall stability of the structure. the reinforcement stones ranged from 300 pounds to over six tons. they were positioned to taper approximately 50 feet downstream from the dam, with the toe of the taper anchored into the river bedrock.

this tapering effect eliminates two deadly aspects of the dam, the five-foot drop from the crest and the recirculating currents that form in the systems plunge pool. the creation of these rock rapids have the added benefit of increasing aeration of the water, in turn creating a more suitable environment for fish and other aquatic wildlife.

our team also recommended plugging a six-foot-wide gap in the dam that remained from a no longer used penstock. at one time, the penstock was used to direct waters for onsite mill operations. prior attempts to fill the hole with wood and stone lodged into the opening proved unsuccessful. to slow the passing water, our team recommended using a special blend of concrete chemically enhanced to “self-settle” and withstand the flowing water. this method was the best and most cost-effective solution to cast and fill the problematic hole.

close-up view of dam penstock filled with loose stone and wood pieces.

structural repairs support long-term plans for natural rapids 

while this structure remains stable and continues to protect the community water source, the ultimate goal is complete removal of the low-head dam in the near future. the city of panora, iowa department of natural resources (dnr), and guthrie county conservation are in the process of developing a concept, design, and funding options for a future long-term solution. the repairs implemented by the snyder & associates team were designed to conform to the long-term goal of establishing natural rapids in the location while still reinforcing the existing structure.

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the fourmile creek watershed spans approximately 119-square miles in portions of polk, boone, and story counties in central iowa. throughout this vast region, urbanization is occurring at a rapid rate. this increase in developed land has intensified flooding, erosion control, and water quality issues surrounding fourmile creek. in 2012, local communities teamed with the engineering and environmental professionals from snyder & associates to form one of the first watershed management authorities in the state — fourmile creek watershed management authority (fcwma) — to better address these serious problems.

comprised of 世界杯足球比赛预选赛 and private representatives from each community in the watershed, as well as officials from each county’s soil and water conservation district offices, the fcwma was established to protect and enhance water quality in the watershed by merging their varied resources and individual interests to accomplish a common goal.

developing a sound watershed management plan

shortly after the fcwma’s founding, the group received a watershed 2022世界杯32强预选赛 grant from the iowa department of natural resources (dnr) and the iowa economic development authority (ieda) to aid in its development. with these added funds, the authority worked to create a watershed management plan that outlined a series of goals to reduce flooding and improve water quality.

the first step in this process included the compilation of a detailed watershed assessment. the snyder & associates team provided data they gathered from extensive hydraulic and hydrologic modeling and prepared recommendations for flood reduction, rural and urban land 2022世界杯32强预选赛 management and development, stormwater detention, and stream corridor restoration. equipped with this information, along with input from rural and urban residents, local leaders, and environmental agencies, the fourmile watershed management plan was assembled.

wma members attend a group meeting to discuss goals and objectives.

using that plan as a guide, the fcwma team has completed a great deal of work in the intervening years. this includes extensive floodplain modeling and most recently, a letter of map amendment (loma) for the city of slater. this plan continues to strengthen the partnership between rural and urban residents and helps provide improvements to the surrounding communities.

city and county leaders have been incredibly proud of the work that’s been performed as a result of the fcwma formation. the numerous jurisdictions impacted by the watershed have been completely engaged with the process, enabling multiple initiatives to move forward. several members envision the fcwma’s progress to stand as an example for similar watersheds around the state and the country.

environmental excellence award recognizes program success

a short three years after its formation, the fcwma was a recipient of the governor’s iowa environmental excellence award for implementing viable environmental improvements on fourmile creek. presented annually by the current governor, this award is given to a handful of iowa businesses and government institutions for efforts made to adopt environmentally sustainable strategies that advance the preservation of the state’s natural resources. it also serves to recognize the contributions made by the authority’s members.

wma members, local officials, landowners, and community staff review on-site work at fourmile creek.

the fourmile creek watershed management authority involves a team of individuals from several walks of life — large and small communities, rural and urban areas, 世界杯足球比赛预选赛 and private organizations. however, they all share a common interest in the fourmile creek watershed. thanks to the efforts of this group, several sustainable initiatives have been implemented and will continue to be implemented, to improve water quality and flood reduction in this vast and treasured resource.

view the complete report.

read more details on the governor’s iowa environmental excellence awards. the awards are sponsored by the governor’s office, the iowa department of natural resources, the iowa department of agriculture and land stewardship, the iowa department of economic development, the iowa department of education, the iowa department of 世界杯足球比赛预选赛 health, and the iowa waste reduction center.

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located on the western edge of creston, lake mckinley has suffered from siltation problems due to excessive erosion and other water quality issues that have impacted the community’s ability to make full use of this once valuable resource. to reverse these negative impacts, creston city leaders partnered with the engineers and environmental scientists from snyder & associates to evaluate these quality problems and offer viable, long-term solutions.

as the primary feeder stream into lake mckinley, hurley creek starts at the watershed’s northern border and flows through a dam just upstream of the creston urban area. from there, the creek meanders southwest through creston to drain into lake mckinley. residential and commercial development surrounding the creek’s path has progressed considerably in recent years. as this growth continues, the amount of impervious areas also increases, resulting in more water volume flowing into local streams and lakes. this increased runoff accelerates soil erosion, moving soil particles, organic materials, and other nutrients into receiving waters. as a result, these factors have decreased the water quality and depth at lake mckinley, significantly degrading the aquatic environment necessary to sustain a healthy and productive lake.

inlet pond pretreats inflow and reduces pollutant loading in lake

aerial view of finished stream restoration and sediment basin located just above lake mckinley.

after extensive testing and study, our team of engineers and environmental scientists proposed a sustainable and cost-effective conceptual layout. this plan was based on site conditions and water quality modeling and provided a vision for implementing improvements in phases and according to established partnerships and community support. our recommended improvements considered valuable resources like wetland species and more significantly, included the addition of an upstream, pretreatment pool to reduce sediment and nutrient loading to the lake.

utilizing vacant city land surrounding the stream, a two-acre pretreatment basin was excavated just north of the lake, followed by streambank stabilization efforts to reduce bank erosion and sediment loading into lake mckinley. this integrated system contributes significantly to tackle two significant drivers affecting lake water quality and aquatic habitat — sediment and nutrient loading. as the water slows through the pretreatment basin, suspended sediment settles to the bottom so that cleaner water reaches the lake. another auxiliary benefit of the targeted sediment removal area is improved accessibility for ongoing maintenance.

nitrogen and phosphorus are the two most prevalent nutrients affecting iowa’s waters, often overloading water resources and causing uncontrolled algae growth and other water quality problems. significant increases in algae harm food resources and aquatic habitats while decreasing the oxygen that fish and other aquatic life need to survive. environmentally designed ponds promote increased plant diversity that optimize nitrogen and phosphorus removal, thus reducing nutrient loading. the addition of the pretreatment basin also helps to increase the aquatic habitat diversity that supports thriving fisheries.

water quality improvements offer sustainable, long-term solutions

hurley creek leading into its new sediment pond.

through the hurley creek water quality project, our team of experts implemented a series of best management practices (bmps) in targeted areas, which reduced sediment delivery to the lake and improved water quality. as our team continues to monitor nearby wetlands, we’ve documented continual improvements resulting from the implemented measures.

this initiative highlights the significance of further watershed-wide water quality bmps to continue improving highly-valued water resources. as lake mckinley sustains these improvements, the community can look forward to the area regaining its position as a recreation hub for residents to enjoy and the creation of a safer and higher aesthetic value for the community as a whole.

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since its creation in 1967, the 464-acre easter lake park on the south side of des moines has been a popular outdoor recreation destination – often hosting over 400,000 visitors a year. managed by the polk county conservation board (pccb), the park offers a range of amenities, including five picnic shelters, three playgrounds, volleyball courts, and multi-use trails. additionally, the park supports a number of outdoor activities like geocaching, hiking, and bicycling.

but perhaps the highlight of the park is the 178-acre lake. stocked yearly by the pccb, the lake draws anglers from around the region looking to catch bass, walleye, and catfish. a boat ramp provides access to the lake for fishermen and recreational boaters alike. easter lake is also the perfect location for canoeing and kayaking on its calm, no-wake waters. during the summer, a swimming beach is open on the lake’s north side to round out the entertainment options.

lake receives “impaired waters” designation due to poor water quality & heavy sedimentation

unfortunately, throughout the 1990s and early 2000s, the lake struggled with diminishing water quality as residential development in the lake’s watershed increased. issues such as poor water clarity, algal blooms, high phosphorus rates, and low oxygen concentrations led to easter lake being added to the state of iowa’s “impaired waters” list. the sedimentation issues, along with increased shoreline erosion, decreased the lake’s size (both in area and volume).

in addition, an increase of invasive fish populations resulted in a poor fishery, while the water clarity and quality issues led to health alerts being issued to swimmers on many occasions over the years. all of these issues resulted in easter lake not reaching its full potential as an outdoor enthusiast’s destination of choice.

the birth of the easter lake water quality management plan

in response to these water quality problems, numerous stakeholders came together to develop the easter lake water quality management plan in 2012. co-sponsored by the iowa department of natural resources (idnr), the city of des moines, and the pccb, this 10-year plan resulted from the compilation of existing studies (performed by iowa state university scientists and the natural resources conservation service) and consultant’s recommendations for structural and non-structural best management practices (bmps). the goal of these studies was to advance methods to reduce the delivery of pollutants to the watershed, reduce stormwater runoff, and create a path for the renovation and restoration of easter lake as a vibrant recreation hub for des moines and the surrounding area.

the easter lake water quality management plan would serve as the baseline for the design work performed by snyder & associates. since the restoration project recommendations outlined in the plan were wide-ranging and involved numerous types of construction and expertise, our firm was hired to provide 2022世界杯美洲杯预选赛 services. projects were divided into several phases that allowed for better contractor specialization to guide the project’s success. core projects designed and planned by snyder & associates included:

this concept rendering shows proposed structural improvements to be completed for the easter lake restoration project.

• new spillway design and fish-rearing pond improvements
• creation of a lake drainage plan
• sedimentation basin design and drainageway improvements
• hydraulic dredging plan
• stormwater wetland improvements
• multi-use trail project design
• lake-grading management and shoreline restoration design
• fish habitat restoration

extensive environmental permitting required for lake improvements

before work could begin on any of the easter lake projects, permits needed to be obtained from multiple agencies. obtaining permits for a project of this size and scope is a project in itself. the process involves numerous environmental surveys, assessments, analyses, and documentation. snyder & associate’s environmental team performed all of the permitting work and provided all of the services necessary, including:

• three wetland and stream delineations
• one biological assessment
• three threatened & endangered species surveys
• two bat habitat surveys
• two cultural resources investigations
• two alternatives analyses
• three 404 permit application submittals through the u.s. army corps of engineers (usace)

our environmental staff collaborated extensively with design engineers, the pccb, the usace, and the iowa dnr in order to obtain the needed permits. given the detailed level of engineering and environmental documentation we provided, most agencies were able to expedite their review and issuance of permits. one of the permit conditions included the purchase of wetland mitigation credits from a wetland mitigation bank. our team diligently worked through this process to ensure all conditions were met.

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the wra fourmile creek improvements-north of broadway project protects vital infrastructure while fostering improved ecological functions and habitat. traditional infrastructure protection with riprap at single bends was abandoned because of the low ecological value. generally speaking, the ecological value of an organism, natural resource, activity, and other components of natural ecosystems are defined by the benefits they provide to support native life.

integrating ecological lift techniques within this complex project has garnered a 2019 engineering excellence honor award from the acec-ia.

this project began when streambank erosion at several fourmile creek locations put sanitary sewer infrastructure at risk. snyder & associates’ experience with environmental engineering, fluvial processes, and stream restoration prompted the des moines metropolitan wastewater reclamation authority (wra) to seek our assistance on a creative solution to address the issue. collaboration was essential in creating a vision for the project as well as identifying project priorities and opportunities.

by reading the river and using natural channel design concepts, this project transformed an environmental liability into an improvement that:

• boosts water quality through sediment loading reductions and vegetative filtering of nutrients
• strengthens the safety of stable/non-vertical banks
• reduces the risk of downstream flooding
• creates a user-friendly recreational environment
• enhances the aquatic habitat for fish and other living organisms

funding assistance strengthens project impact

wra embraced the opportunity to leverage srf sponsored project funding associated with their infrastructure improvement loans. as a result, they expanded a limited bank stabilization project to protect their sanitary sewer infrastructure into a comprehensive stream restoration approach that benefits longer reaches.

through several applications, we helped the wra secure $4.2 million in funding assistance to leverage their limited traditional funds. we were also able to successfully coordinate with multiple agencies and partners to facilitate right-of-way acquisition and meet funding requirements. over 8,000 feet of stream restoration was prioritized in three fourmile creek reaches—north of broadway avenue, north of euclid avenue, and south of university avenue—to reduce severe bank erosion and channel degradation, and protect sanitary sewer infrastructure.

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meandering through central iowa, ioway creek, formally known as squaw creek, is a 42-mile-long tributary that empties into the south skunk river on the southeast side of ames. due to the waterway’s steep banks, highly erodible soils, and volatile flooding events, significant streambank erosion had occurred over many years. the erosion had progressed to the point that it threatened the stability of a 24-inch water main running under the creek near the lincoln way bridge.

this pipeline transports potable water to serve approximately 18,000 residents in the area along with the entire region containing iowa state university. previous attempts to control the erosion issue in this highly flood-prone region were unsuccessful, prompting the ames city leaders to seek a sustainable, long-term solution. snyder & associates was contracted to recommend engineering techniques that could stabilize the creek banks, in turn protecting the existing water main.

adjustments made in 2022世界杯32强预选赛 phase produce added safety features

restored ioway creek stream during low-flow conditions

throughout the analysis and 2022世界杯32强预选赛 phase, the project evolved into a more extensive undertaking, addressing safety concerns regarding a low-head dam located in the area. the dam created circular currents that compounded the streambank erosion, impeded fish passage, and posed a drowning hazard. this adjustment was proved necessary as two kayakers narrowly survived a life-threatening situation after being sucked into the dam’s undertow. occurring just before the project’s completion, this timely incident drew further attention to the safety hazards posed by low-head dams.

working with the federal emergency management agency (fema) for over six years, hazard mitigation grant program (hmgp) funding was secured to finance the streambank stabilization project and mitigate the threat posed by the dam. the many streambank stabilization efforts our team incorporated involved:

• flattening both the east and west bank of the creek
• incorporating a low-flow bench to reduce flow velocities and bank pressure
• protecting lower banks with a stone revetment
• reinforcing upper banks with erosion control mat, native vegetation, and live stakes

rock arch rapids: an alternative to complete dam removal

while city leaders desired the complete removal of the low-head dam, a scour analysis performed by the snyder & associates team indicated the dam protects the piers of the lincoln way bridge and another water main immediately upstream. to meet the client’s request for complete dam removal while also producing a stable mitigation option, our experts were challenged with creating an innovative alternative.

rock weir provides a gradual drop for improved fish passage and recreational safety.

our team determined the construction of rock arch rapids would be perfectly suited for this location. rock arch rapids are a series of steps that gradually transition water flowing downstream from the dam to meet channel elevation. the stream section where a wall-like concrete dam once stood, now features a gradual stretch of rock barriers. this solution slowed the flow of the stream, reduced erosion on the banks, and eliminated the roller (or boil) below the dam. by implementing this tiered structure, our team was able to improve safety for recreational stream users and create a series of pools that allow fish to migrate upstream.

once completed, this project successfully protected city infrastructure, improved stream functions, and stabilized the streambank. also, the outcome helped improve recreational safety, restore stream connectivity, and enhance the aquatic and riparian habitat in the area. partnerships between the city of ames, state and federal regulatory agencies, and other interested stakeholders helped drive the success, leading to the project being highlighted during the 11th annual iowa water conference.

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summit lake flooding causes significant damages and is in need of repairs

originally built in the late 19th century, summit lake spans 250 acres across the west side of creston, iowa, and is a popular destination area for fishing and recreational use. for many years, the lake was privately owned by the municipal taxpayers water company until the city of creston purchased it in the mid-1930s. almost immediately after purchasing, the city raised the earthfill dam and spillway to almost double the capacity of the reservoir. this arrangement lasted until the historic floods of 2008 caused significant deterioration.

creston water works partnered with snyder & associates to inspect the flood damage and develop a plan for making any needed repairs. because repair work would likely require lowering the water level in the lake, the decision was made to seek out funding assistance and address several other lake issues at the same time. these include making improvements for better recreational access to the lake and stabilizing the erosion-damaged shoreline.

spillway repair & reconstruction to keep dam stable

the snyder & associates team evaluated the dam and spillway and provided an extensive engineering report detailing our findings. after conducting a multitude of tests, it was clear damage was evident and a geotechnical exploration was undertaken to determine the dam’s underlying stability. after the evaluation, it was determined that the earthen section of the dam was in stable condition.

however, the spillway section had developed hollow pockets underneath the concrete. this was allowing lake water to seep beneath the spillway putting the entire dam at risk. since this structure was built nearly 100 years ago, very little design information existed. our design team utilized their years of expertise with dam removal and modification to determine hazard risks and formulate a cost-effective repair plan.

with the scope of the damage known, we designed a modern spillway replacement that would enable the city to maintain the lake in a safe and usable condition. our team began by creating a dam breach analysis report to determine hazard classifications and

the old spillway section had developed hollow pockets underneath the concrete.

assure downstream safety measures were adequate before the reconstruction was permitted by the iowa department of natural resources (idnr).

throughout the entire design and analysis process, the spillway continued to have a constant stream of water flowing below the concrete, decreasing its ability to withstand large flows of water. working with the city, permitting agencies, and stakeholders, our team developed a plan to substantially drain the lake to allow construction efforts and increase safety measures.

the new concrete spillway section was designed to safely accommodate the expected flow rates established by the breach analysis. this design included a new energy-dissipating outlet structure, stilling basin, and downstream creek stabilization efforts to eliminate erosion on the new structure. the new spillway section was also constructed vertically, as opposed to sloped, to comply with idnr regulations concerning the control of undesirable fish migration into the lake. additionally, our team assisted the creston water works in securing funding from fema and the iowa department of economic development (ided) to help make the needed improvements economically feasible.

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