Concurrent Session III, Track A

1113: Permanent BMP Maintenance: Implementing Inspections for BMP Success

Author(s): Mary Fitzgerald, Ramsey-Washington Metro Watershed District

Description: Ramsey-Washington Metro Watershed District (RWMWD) implements two programs that focus on conducting annual inspections of Stewardship Grant and Permitted stormwater BMP projects. These programs aim to intervene early in the project process to ensure BMPs are installed properly, have good functionality once construction is complete, and continue to function year after year well beyond project completion. RWMWD staff complete annual inspections of both Stewardship Grant and Permit BMPs and report findings to owners requiring necessary maintenance of plants, structures, and any other noted items. The goal of this presentation is to describe RWMWD’s BMP maintenance programs, and deliver possible first steps to other entities who are interested in implementing similar programming.

1106: Development of a Non-City Owned Stormwater Infrastructure Assets Inventory and Inspection Program

Author(s): Jessica Wilson, City of Edina; Nathan Campeau, Barr Engineering Company; Aaron Mielke, Barr Engineering Company

Description: Non-City owned stormwater infrastructure assets are an important component of a community’s surface water management strategy to protect water resources. One of the highest value activities for a surface water management program is to ensure that these assets continue to work as designed to prevent or reduce the discharge of pollutants to downstream lakes and streams. The City of Edina, with assistance from Barr Engineering Co., applied asset management principles to establish a framework for inventorying and inspecting non-City owned stormwater infrastructure assets. We used development review records, construction stormwater permit data, and Hennepin County records search to research assets and build the inventory in GIS.

We then developed a custom GIS-based SQL database schema to support data entry forms for various asset types. Asset conditions were recorded in the field with an iPad using the ArcGIS Online (AGOL) Field Maps application. Inspections include an operational rating, and a structural condition rating to assess the overall general condition of the asset using a rating system similar to the National Association of Sewer Service Companies (NASSCO) Pipeline Assessment Certification Program (PACP) and Manhole Assessment Certification Program (MACP) rating systems.

The results of the inspection were uploaded in real-time via cellular data connection into the SQL database and used to create inspection reports for owners. The database is also connected to an AGOL web map and dashboard that allows City staff to track inspection progress and asset condition.

This program will maximize the overall lifecycle of assets, improve regulatory compliance, and help keep the practices operating as designed and permitted to protect water quality and mitigate flooding. We’ll share the program framework, asset discovery methodology, inspections web application, inspections procedure, and results from two years of comprehensive inspections.

1054: Benefits of a Residential Stormwater Management Grant Program

Author(s): Erick Francis, City of St. Louis Park

Co-presenter: Jennifer Ehlert, Metro Blooms 

Description: The City of St. Louis Park’s Rainwater Rewards program began in 2017 to assist residents in managing stormwater on their property. Since then, the program has installed almost 200 rain gardens, in a collaborative effort with Metro Blooms, the Conservation Corps of Minnesota and the Clean Water Fund. The program has also assisted residents install other best management practices, such as trees, native plantings, rain barrels, pervious pavers, and even a customized water reuse system, all improving water quality and improving habitat.

The program helps the city comply with several of the MS4 permit requirements, including public education, public engagement, post-construction stormwater management, and reducing pollutants from entering our surface waters.

An additional benefit of the program is that it provides an innovative approach to addressing residents’ shared drainage issues, which can be complicated, but are considered a civil matter. The program provides residents with an opportunity to address their drainage issues, to improve their properties, and allows for a quick resolution and to achieve positive outcomes.

As the program moves into the future, the city is looking to expand the program to reach multifamily residents and to assist commercial properties as part of the city’s depaving program.

1053: Plants for Stormwater Design, Interactive Selection Tool for Stormwater Professionals and the Public

Author(s): John Bly, Metro Blooms; Dan Shaw, BWSR; Rich Harrison, Metro Blooms; Mike Trojan, MPCA

Description: This project fills a key need for an online resource allowing stormwater professionals as well as the general public to easily choose appropriate and successful native plant species and seed mixes for vegetated stormwater practices in different site conditions and state regions. We are updating the Minnesota native plant search tool Blue Thumb Plant Finder to include more commonly planted native species and information about them, and pull in other available and relevant data (drought tolerance, erosion susceptibility, etc.) where possible. Upon completion, the tool will be linked to vegetated stormwater practice information in the Minnesota Stormwater Manual, a comprehensive and still growing collection of background and design information about stormwater Best Management Practices for stormwater practitioners across the state.

The plant finder’s database will be structured so that it can be searched with a variety of filters and tags, so that practitioners can “describe” a site that needs planting, including adverse site conditions and special parameters, and be given a detailed list of plant species and/or seed mixes that are most likely to succeed on the site.

Work on the project is currently underway and we hope to have the tool live by summer.

Concurrent Session III, Track B: Watershed Planning & Management

1115: The Uses of the Hydrological Simulation Program FORTRAN at the Minnesota Pollution Control Agency and the Scenario Application Manager Tool

Author(s): Charles Regan, Minnesota Pollution Control Agency; Seth Kenner, RESPEC Consultants; Sagor Biswas, Minnesota Pollution Control Agency

Description: The Minnesota Pollution Control Agency (MPCA) uses the Hydrological Simulation Program FORTRAN (HSPF) to carry out several of its business needs. These needs include the development of Total Maximum Daily Load (TMDL) allocation studies and the setting of pollutant effluent limits for point sources. These activities are required by the United States Environmental Protection Agency (USEPA). The MPCA first used HSPF in the Minnesota River Basin but has now applied HSPF statewide. Recently, RESPEC has developed the Scenario Application Manager (SAM) which connects an HSPF model to a Geographic Information System (GIS) interface and a Best Management Practices (BMP) database. SAM has allowed users to more easily develop and execute implementation scenarios to meet local water quality goals. Case studies will be presented.

1026: Priority Lakes: Meeting Protection Goals and Multiplying Benefits

Author(s): Crystal Mathisrud, Hubbard County SWCD; Gary Michael, MN DNR; Brandon Spain Brist, Hubbard SWCD; Lindberg Ekola, MN BWSR; Dan Steward, Hubbard SWCD; Jim Stark, Legislative Subcommittee on Water Policy

Description: Water is a key resource in Minnesota, the land of 10,000 lakes. Not only is it important as a resource for clean drinking water, but it is the headwaters for some of the most important water bodies in North America, including the Mississippi River. These waterways and the thousands of lakes make recreation and tourism an important economic driver in Minnesota, especially in rural communities.

The Minnesota DNR, through its Private Forest Management (PFM) program, has partnered with the Minnesota BWSR, in tandem with SWCD’s, consulting foresters, and environmental organizations for decades. GIS tools and RAQ scoring, which were developed by partners based on Pete Jacobson’s research, are used to identify priority areas for protection. Ensuring no more than 25% of land within a watershed is disturbed, at any given time, best protects present and future water quality and aquatic habitats. This approach allows the state to meet water quality goals, while at the same time acknowledging the crucial role private forest landowners play in maintaining forested landscapes. Priority watersheds in Hubbard County, such as the Kabekona, will reach the 75% protection goal by 2024 using this process. The Steamboat watershed is under-protected, but using this process we intend to reach the 75% protection goal in the near future.

Minnesota's northern forests have the power to multiply benefits, including; water quality, soil health, reduce impact of drought/intense rainfall, produce and nurture wildlife, grow record walleye/trout, enhance family life, sequester/store carbon, and grow products that sustain local economies forever.

1118: Watershed Restoration and Protection Strategies (WRAPS) – What Has Been Accomplished and Where Are We Going?

Author(s): Heather Johnson, Minnesota Pollution Control Agency; Theresa Haugen, Minnesota Pollution Control Agency

Description: The Minnesota Pollution Control Agency (MPCA) has a long history of providing funding to and working with partners around the state to address water quality concerns. In the 1990s, the focus was through state Clean Water Partnership and federal Clean Water Act Section 319 projects, typically on a specific water body. With the passing of the Clean Water, Land and Legacy Amendment in 2008, increased funding allowed the MPCA to address water quality concerns on multiple fronts through watershed-wide work. To address the needs for the 80 major watersheds of the state, a comprehensive approach, which includes Watershed Restoration and Protection Strategies or WRAPS, was implemented. These reports pull together information on water quality monitoring, stressors, and modeling, as well as incorporate Total Maximum Daily Loads (TMDLs) findings for impaired waters, and strategies for non- impaired waters and impaired waters not addressed by TMDLs. This presentation will explain the WRAPS process, showcase several success stories and discuss what’s next now that all initial 80 WRAPS have been completed.

1116: Total Maximum Daily Load Studies in Minnesota

Author(s): Andrea Plevan, Minnesota Pollution Control Agency

Description: A total maximum daily load (TMDL) is the maximum amount of a pollutant a body of water can receive without violating water quality standards. The TMDL process identifies all sources of a pollutant to an impaired water body and determines how much each source must reduce its contribution to meet the standard. TMDLs may set limits on pollutants entering water bodies and serve as planning tools for improving water quality. TMDLs can also identify areas of high pollutant loads and indicate locations where reducing a pollutant would be particularly beneficial.

The Minnesota Pollution Control Agency (MPCA) and project partners have been developing TMDLs in Minnesota since the 2000s, and TMDLs have been approved for over 1, 800 impairments in the state. The state’s first TMDLs typically were developed for one water body at a time. In the mid-2000s, Minnesota adopted a watershed-based management approach, and MPCA began developing TMDLs for multiple impaired water bodies within a major watershed. As part of the watershed approach, TMDL results are incorporated into Watershed Restoration and Protection Strategy (WRAPS) reports, and WRAPS findings are incorporated into One Watershed, One Plan (1W1P). Thus, TMDL studies provide the initial technical analyses needed for watershed managers to determine the actions needed to restore water bodies.

This presentation will step through the process of completing TMDLs and will discuss how TMDLs are used in other watershed projects and plans.

Concurrent Session III, Track C: Causes and Solutions for Harmful Algal Blooms

1034: Harmful Algal Blooms in Remote Lakes Require Management Strategies Beyond Watershed Nutrient Reductions

Author(s): Amelia Wilson-Jackson, Science Museum of Minnesota - St. Croix Watershed Research Station; Lienne Sethna, Science Museum of Minnesota - St. Croix Watershed Research Station

Description: Harmful algal bloom (HAB) management relies on reducing watershed inputs of phosphorus (P) and research has focused primarily on culturally eutrophic systems; however, HABs have been increasingly documented in remote lakes. The factors controlling these blooms are not well understood and require more research into environmental drivers beyond watershed nutrient inputs. We examined eight lakes within protected areas of northern Minnesota to explore the effects of lake thermal structure on phosphorus availability and algal ecology. Specifically, we explored how warming has influenced internal P loading and its effect on the density and toxicity of cyanobacteria. We used water quality monitoring and paleolimnological reconstructions to determine the relationship between P availability and algal ecology through time. Preliminary data show lakes were P limited and P concentrations were positively correlated with cyanotoxin (microcystin) concentrations. Dated sediment cores will be analyzed for sediment P fractions, microbial DNA, and algal pigments. The total concentration and forms of P in the sediment indicates biogeochemical processes affecting P cycling and the potential for increased internal P loading. Microbial DNA and algal pigments reconstruct algal community composition and functional traits such as N-fixation and toxin production. The combination of these techniques provides a quantitative interpretation of the timing and extent of harmful algal taxa as it relates to P availability. We will complete sample analyses by August 2023. By providing historical context of HABs in remote systems, this work aims to inform new management and mitigation strategies for freshwater systems that goes beyond traditional watershed nutrient reductions.

1047: From East Coast to the Rocky Mountains: Successful Application of Hydrogen Peroxide for Proactive Algal Management

Author(s): Elizabeth Crafton-Nelson, Hazen and Sawyer; Emma van Dommelen, Hazen and Sawyer

Description: Harmful algal blooms (HABs) are a prominent issue for surface water systems that will be exacerbated as effects of climate change continue to materialize and anthropogenic influences grow. The drivers behind HABs are complex and require a multifaceted remediation plan that covers watershed and in-situ management efforts. The most common responsive management strategy to control growth is algaecide. Historically, copper-based algaecides have been used to control algal growth, which inactivate cells through nonselective toxicity, impacting nontarget organisms. Alternatively, hydrogen peroxide based algaecides can be used to selectively target bloom-forming cyanobacteria with minimal cell lysis. Peroxide-based algaecides can achieve prolonged suppression, reducing the number of treatments needed, providing cost savings, and optimizing treatment plant operations during summer months. This presentation covers the fundamentals of hydrogen peroxide-based algaecides; comparative bench testing of copper and hydrogen peroxide products to assess overall efficacy and release of intracellular material; and includes five cases studies from across the country where it was effectively employed for cyanobacteria control. Lessons learned, critical success factors, and benefits for each case study will also be covered. Lastly, the outcomes of each case study will be compared across the varying systems to identify best practices for hydrogen peroxide-based algaecide treatments.

1061: Water Quality Drivers of Harmful Algal Blooms in Cedar Lake and Lake Nokomis

Author(s): Katelynn Chamberlin, Minneapolis Park and Recreation Board; Rachael Crabb, Minneapolis Park and Recreation Board; Katie Turpin-Nagel, Barr Engineering Co.; Joseph Bischoff, Barr Engineering Co.

Description: Cedar Lake and Lake Nokomis are recreational lakes in the City of Minneapolis including five beaches between the two lakes. While both lakes are meeting water quality goals for phosphorus, phytoplankton communities are dominated by cyanobacteria, many of which are toxin producers. The Minneapolis Park and Recreation Board (MPRB) identified severe cyanobacteria blooms at beaches and boat ramps with detectable cylindrospermopsin and microcystin concentrations exceeding local advisory thresholds. To develop a management strategy to control cyanobacteria blooms, MPRB developed a stressor analysis to identify the primary drivers for the Harmful Algal Blooms (HABs) and to identify strategies to eliminate these blooms. Cedar Lake strongly stratifies and demonstrates high hypolimnetic (often > 500 µg/L) and metalimnetic phosphorus (P) concentrations (often > 300 µg/L) while surface P concentrations remained near or below MPCA deep lake standards (< 40 µg/L). These higher P conditions at lower depths favor cyanobacteria that can control buoyancy whereby the cyanobacteria move to the nutrient rich thermocline to access high P concentrations and then back to the surface for high light conditions. These conditions are likely exacerbated by climate change where the extent and duration of stratification are increased as temperatures warm. In contrast, Lake Nokomis demonstrated weak temperature stratification with high sediment P release (4 to 23 mg/m2/day). These conditions allow periodic sediment anoxia resulting in P release that easily entrains to surface waters. Under these conditions, cyanobacteria can access high P waters all summer, controlling buoyancy to access P when it’s near the sediments or competing for high P throughout the water column. Since nutrient enrichment and internal P loading were identified as the primary driver of cyanobacteria blooms, controlling sediment P release in these lakes will likely reduce cyanobacteria bloom frequency and intensity.

1069: Translating Successful Reservoir Restoration Methods to Lakes in Minnesota

Author(s): Roger Scharf, Jacobs Solutions; David Austin, Jacobs Solutions

Description: A reservoir is a lake with a budget. Although a jest, this definition gets to the practical heart of why reservoir restoration across the United States has advanced rapidly. Utilities face large capital and operational costs to deal with water quality impacts on drinking water production or power generation. In basin ecologically engineered improvements entail a small fraction of those costs. Consequently, reservoirs get budgets to improve water quality.

Low cost for a utility is not necessarily low cost for local governments wanting to restore nutrient impaired lakes. Pure oxygen systems that have sharply improved water quality in reservoirs do not easily translate to these lakes even when technically straightforward. Can we adapt the lessons of success from reservoirs across the United State to lakes in Minnesota?

Pure oxygen systems eliminate hypolimnetic anoxia in reservoirs. Doing so creates a geochemical cascade that strongly suppresses harmful algae blooms (HABs) and lowers the trophic state. Cyanobacteria need anoxia to fix nitrogen and to get phosphate and iron from sediments to drive blooms. Winter hypolimnetic anoxia is common in Minnesota mesotrophic to eutrophic lakes. Winter anoxia drives internal nutrient loading that raises spring Chl-a that sets sediment oxygen demand (SOD). High SOD causes summer anoxia that drives HABs. Preventing winter anoxia trims summer anoxia by reducing the lake anoxic factor.

Lake physics favors ice-preserving, hypolimnetic aeration, making it possible to keep dissolved oxygen at saturation under the ice. It is a major technical improvement over traditional winter aeration and summer destratification aeration. It is simple to design and implement. Additionally, the ease of mixing facilitates geochemical augmentation with alumina to sequester lake TP in sediments. This presentation will summarize design rationale and its parallels with the design philosophy of reservoir water quality improvement projects.

Concurrent Session III, Track D: Reducing and Prioritizing Flood Risk

1059: Storing Water in the Lake: Flood-Risk Reduction on the Phalen Chain of Lakes

Author(s): Paige Ahlborg, Ramsey-Washington Metro Watershed District; Brandon Barnes, Barr Engineering Co.

Description: In urban watersheds identifying and pursuing flood-risk reduction retrofits are challenging. Often space is at a premium and balancing diverse—often conflicting—stakeholder input can limit the number of feasible options. Ramsey-Washington Metro Watershed District recently completed a retrofit of the outlet control structures on the Phalen Chain of Lakes in St. Paul to allow real-time operation of the outlets. The operation of the structures allows for creating live storage volume prior to a flood event to store stormwater runoff in the lake. In this talk, we’ll share the journey from watershed-scale planning and identification of flood-prone structures, through conceptual ideas, hydraulic modeling, to ultimately permitting and implementation of an operation plan that considers current water levels and rainfall forecasts to inform adjustment of the outlet control structures to remove habitable structures from the floodplain.

We will discuss lessons learned through taking a watershed-scale approach for identifying flood-prone structures, communicating with stakeholders, and eventually implementing projects to reduce upstream flood-risk while not adversely affecting downstream flood-levels. We will also cover the approach toward hydraulic modeling; specifically challenges associated with setting up simulations to inform development of the operation plan for a wide range of rainfall events, starting water levels, and initial conditions needed to develop an operation plan.

NOTE: This abstract would pair with the abstract titled Lower the Gates (Except When They Shouldn’t Be Lowered) – Lessons Learned Operating Adjustable Lake Outlet Control Structures.

1057: Lower the Gates (Except When They Shouldn’t Be Lowered) – Lessons Learned Operating Adjustable Lake Outlet Control Structures

Author(s): David Vlasin, Ramsey-Washington Metro Watershed District; Brandon Barnes, Barr Engineering Co.

Description: Construction bid prices are increasing, urban development limits available space, and input from a diverse group of stakeholders has changed the way Ramsey-Washington Metro Watershed District (RWMWD) has approached flood-risk mitigation in some parts of the watershed. RWMWD has retrofitted lake outlet control structures to allow for adjusting the outlet level prior to a rainfall event. Retrofits have included modifications that allow for manual adjustment of outlets and incorporating the latest technology that allows staff to adjust outlets from a remote location using an application on staff cell phones based on real time monitoring of lake levels. In addition to remote operation of lake outlet control structures the system also sends a warning when the system is not responding as anticipated. RWMWD staff will share lessons learned from operation of lake outlet control structures during periods of high and low water levels and explain why everything works great—until it doesn’t. Staff will share problems and solutions to deal with poor cell connections, vandalism, and other ongoing maintenance struggles. Differences between operating lake outlet control structures that require manual adjustments from onsite compared to structures that can be operated from a remote location, and experiences communicating with the general public and managing expectations for when outlet control structures can be modified.

This abstract would pair with the abstract titled Storing Water in the Lake: Flood-Risk Reduction on the Phalen Chain of Lakes.

1078: From Study to Implementation, How Burnsville Leveraged Their Watershed Model to Create an Impactful Stormwater Project

Author(s): Luke M LaMoore, AE2S; Justin Klabo, AE2S

Description: Watershed wide hydraulic and hydrology models are becoming increasingly common across the Twin Cities metro area. These models help watersheds and cities understand how stormwater flows through their jurisdiction. After the model is built and reviewed, the city is often left with an entire regional model, full of data and results, without a path to implement drainage improvements. Recent efforts from the City of Burnsville provide a successful case study in how communities can leverage their watershed studies to identify, design and construct impactful stormwater improvements. Burnsville took their citywide 2D XP-SWMM model and created a project prioritization tool, a GIS based model that used results from their model to identify critical subwatersheds most in need of stormwater improvements. The subwatersheds of Crystal Lake, South Twin Lake, and North Twin Lake were identified by the prioritization tool as critical with homes at South Twin Lake experiencing inundation and Crystal Lake having a prolonged draw down which caused shoreline erosion and limited recreational opportunities on this popular boating lake. The XP-SWMM model showed that due to their connected nature, all three lakes contributed to these issues, which lead to Burnsville facilitating the design and construction of the Twin Lakes Improvement Project. The project replaced the outlet at Crystal Lake, constructed a new outlet at South Twin Lake and created additional flood storage near North Twin Lake to address the flooding and drawdown concerns. Construction began in summer of 2021 and substantial completion was finished that fall. Finally, the 2D citywide model was once again used to complete the LOMR process the Twin Lakes Improvement Project required. The new construction was added to the model and its output used in the finalized floodplain mapping. The whole process depicts a great example of how large-scale modeling studies can guide city staff to impactful stormwater improvement projects.

1032: Designing GSI to Adapt with a Changing Climate

Author(s): Ben Crary, Hazen and Sawyer; Matthew Jones, Hazen and Sawyer

Description: Green stormwater infrastructure (GSI) can provide multiple benefits and support sustainability efforts; however, characteristics of the small, frequent storms these systems are designed to manage are changing. Climate changes can also shift programmatic priorities from stormwater quality improvement to drainage relief. Under these dynamic circumstances, it is beneficial to understand the role of GSI in stormwater management now and in the future and how current GSI can be implemented to provide flexibility and adaptive capacity for uncertain future conditions.

A hydrologic analysis of multiple bioretention design configurations under current and future climate conditions was performed, with a primary focus on volume capture and peak flow reduction. In addition to assessing a basic bioretention designed to current common standards, two design elements that allow for future operational flexibility were evaluated: an internal overflow and a flow-restricted underdrain.

Hydrologic simulations demonstrated that a basic bioretention design offers limited adaptability to address dynamic storm characteristics of the future and provides minimal peak flow reduction. Incorporation of an internal overflow and underdrain flow restriction both improved volume capture and peak flow reduction performance under future climate conditions while also allowing for the function of a bioretention to shift from water quality improvement to runoff attenuation and drainage relief. This presentation will discuss the analyses described herein and provide recommendations on how the subject bioretention design elements may be incorporated into current designs and simple future modifications to tailor bioretention performance to changing climate conditions and provide better long-term performance.