Updates
November 17, 2023
A note from the research team
Thanks to our donors for supporting our ongoing research on the impact of recreational boating on lake health. A better understanding of when, where, and how boats impact lakes will help communities make informed decisions that balance recreation with keeping our lakes healthy for future generations.
With your generous support, Phase 1 research on boat-generated waves was published in 2022. The interest in this report has been immense and provided the momentum needed to conduct a Phase 2 study on boat-generated propeller wash. With your continued support, our team completed fieldwork in the fall of 2022, with the intent to publish a peer-reviewed report this fall. However, we observed interesting but unanticipated phenomena during data analysis and realized that to publish a thorough Phase 2 report, we needed more data. With funding secured from the Minnesota Environment and Natural Resources Trust Fund (ENRTF) as recommended by the Legislative Citizen Commission on Minnesota Resources (LCCMR), we completed the additional fieldwork this fall. This winter, we will be working to complete data analysis and publish our findings from the combined propeller wash research effort.
Below is a short progress update, photos from the field campaigns, and plans for the next steps.
With deep gratitude,
Jeff Marr - Project Lead
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Updates from Phase 2 propeller wash research
Research questions: For different boat sizes and usage scenarios, how deep does the propeller wash penetrate the water column, and what are the associated water velocities? At what depth does propeller wash begin to interact with the lake bottom, and what happens when it does (e.g., sediment suspension, changes to water quality)
The study: We tested seven different boats, including two wakesurf boats, under various operating conditions (e.g., speed, weight, etc.). In the fall 2022 fieldwork, boats were driven in a straight path over two monitoring sites at depths of 16 ft and 27 ft.
Unanticipated findings raised new questions: Transverse waves (see photo below) form off the stern of the boat and travel in the same direction as the boat. Transverse waves are produced when boats travel below planing speeds. Our fall 2022 data indicates that there is a measurable effect of both propeller wash and transverse waves in the water column and on the lake bottom. It became evident that additional data, collected at shallower water depths, needed to be gathered to parse out propeller wash impacts from transverse wave impacts.
components of a boat wave
boats were driven over sunken data sensors
researchers heading out to collect water samples
ENRTF Grant (Phase 3)
In June of this year, our team was notified that we were awarded ENRTF funding to continue studying recreational boating impacts. This grant will run for three years (2023-2025), with the first year expanding on the Phase 2 propeller wash/transverse wave work. This past fall we collected data at two shallower depths: 9 ft and 14 ft. In addition to velocity, turbidity, and water quality data, we also gathered visual data from underwater cameras and an overhead drone.
Our Phase 2 report was necessarily delayed by this extra field season, but with the data from these additional water depths and videography, we will be able to develop a very robust report on the characteristics of propeller wash and transverse waves and how these are linked to water column mixing, bottom impacts, and water quality.
We aim to publish a peer-reviewed report in the summer of 2024. We know many groups are waiting for this information to help with decision-making. We will work hard to publish a report ahead of the next open-water season.
May 8, 2023
A little over one year ago, our research team at the University of Minnesota published the first research report (Phase 1) to come from our Healthy Waters Initiative Program that characterized the wake waves produced by wakesurf boats and other recreational watercrafts. The report documents the larger size, energy, and power of wake waves produced by wakesurf boats and demonstrates that these boats require larger operational distances when compared to more typical recreational boats. Over the last 12 months, it’s been amazing to witness the impacts this research is having. We receive inquiries on a weekly basis from stakeholders across the country involved in issues related to environmental impacts of wakesurf boats and the sport of wakesurfing. The UMN report, which has been downloaded over 11,000 times, has become a central scientific addition to these debates and is helping boat operators, property owners and resource managers develop approaches to protect lakes and property, ensure water safety, and create opportunities for shared use of water resources.
This past June 2023, we launched a second research effort focused on characterizing the propeller wash produced by wakesurf boats and other recreational watercrafts. You can read more about our project [here]. To date, we have raised approximately $130,000 that allowed us to carry out the field portion of the study this past fall and start the data analysis process. We are still hoping to reach our goal and are grateful for any financial contributions you can make as these funds go directly to support our research team. As with our previous project, we are implementing a high standard for impartiality and will publish a peer-reviewed, open access report of our findings. You can learn more about our crowdfunding campaign and make a donation [here].
In addition to our Phase 2 study, we also want to share the good news that it appears our Healthy Waters Initiative Program will receive funding for a Phase 3 study. We submitted a proposal to the Legislative-Citizens Commission on Minnesota Resources (LCCMR) this past spring that has now been recommended to the MN Legislature for funding. If approved, funding for this three-year project would start July 2023. The project will expand our research on boat generated wake waves and propeller wash impacts on inland lakes. Furthermore, the team will also look at wind generated waves to parse out similarities and differences to boat generated waves. We believe a major strength of our proposal was being able to point to the tremendous financial support we’ve received from donors these past few years through our crowdfunding campaigns. The hundreds of donations that we have received, has without a doubt, conveyed a powerful message that the impact of boating on our shared lakes is a critically important topic to Minnesotans and others across North America.
October 24, 2022
The fall weather cooperated and our team is pleased to report that we have completed the field work component of Phase 2.
Now it’s back to the desk for data analysis. The image below is a sneak peek of the type of data we captured with the Acoustic Doppler Current Profiler (ADCP) that was deployed on the lake bottom. Specifically, the image depicts the backscatter data recorded from a single boat pass over the sensor, where the dark red shows the particles and bubbles entrained in the propeller wash. The vertical axis is distance from the sensor and the horizontal axis is time.
We gathered a lot of data that needs to be combed through over the coming months including, ADCP, Acoustic Doppler Velocimeter (ADV), water quality parameters (physical samples and sonde), and boat position, attitude, and hull displacement. It is anticipated that the resulting data will directly answer the question of how deep propeller wash penetrates the water column for various recreational boats operated under different conditions and any subsequent changes in water quality.
October 3, 2022
The HWI team is happy to report that our Phase 2 field campaign got off to a great start last week. We were able to complete propeller wash testing on 2 boats. If the weather continues to cooperate, we should have our field testing complete by mid-October.
August 25, 2022
It’s been a busy few months for the HWI team and we’re happy to report many positive steps forward:
First, last Wednesday we presented our Phase 3 proposal to the Legislative Citizens Commission on Minnesota Resources (LCCMR). The presentation went well with many questions from the members. This 3-year project is now under consideration for funding by this program, which would allow us to greatly expand the efforts of Phase 1 and Phase 2 work, and begin to make connections to environmental impacts. Keep your fingers crossed as we wait to find out if our project will be selected for the funds that would become available June 2023. Our LCCMR proposal presentation can be watched here (time 39:17).
Second, we have exceeded the halfway point of our crowdfunding campaign for Phase 2 propeller wash research. As of today, we’ve raised just over $100,000 from more than 70 donors. We need to continue raising funds to ensure that we're able to execute our scope of work plan in its entirety. However, with the funds raised to date, we are moving forward with planning and preparing for our field deployment which is scheduled for the end of September. We are currently focused on planning test day logistics, identifying test sites, determining test conditions, purchasing water quality sensors, and selecting boats to test. It’s exciting to back at the table, preparing for field work!
Third, our undergrad student Bryce has made some amazing progress in developing our Citizen Science wave monitoring mast. The mast is deployed in Spearhead Lake thanks to our collaborators Peter Buesseler and colleagues at the Mississippi Headwaters Audubon Society (MHAS). Check out our recent update on the Citizen Science page.
We’ll continue to provide updates as we head into our field campaign.
June 6, 2022
Our team at St. Anthony Falls Laboratory is excited to announce the launch of a second phase of research on boat-generated impacts on inland lakes and rivers. You are receiving this email because you registered for updates through our Healthy Waters Initiative website.
In this next phase of study, we will focus on characterizing the propeller wash that is generated by various types of recreational boats, including wakesurf boats. This is a topic that we’ve heard a lot of concern about over the last few years, and the current body of knowledge is lacking, making this topic an ideal candidate for robust research. To get in the water as soon as possible, we are funding the research through a crowdfunding campaign and would greatly appreciate your financial contribution to this effort. If a donation is not possible, simply spreading the word about our study would be much appreciated.
You can find a full summary of the research plan, budget and schedule on the propeller wash page. We’ve also included a link to the crowdfunding campaign website.
Thank you for your support!
May 23, 2022
We recently conducted a pilot experiment that looked at how propeller wash can disturb bed sediment and generate recirculation in the water column.
For our set up, a 20" wide by 30' long flume was filled with a thin layer of sediment and 3ft of water. To replicate the fixed motor of a boat, we mounted a drill to a carriage that moved along the flume at adjustable speeds. A shaft and propeller were attached to the drill that could be adjusted to accomodate different propeller angles. To better see how the propeller wash moved the water, we fed red clay down the shaft and through the propller blades (see pictures below) as it moved down the flume.
Even though no measurements were taken during the experiment, some important observations were noted: (1) slower speeds penetrated deeper into the water column than faster speeds, and (2) greater propeller angles appear to penetrate deeper as well. These observations can be seen in the pictures below.
This pilot experiment is part of the beginning of the Phase II project, which will focus on the propeller wash produced by recreational boats. We are currently working on a crowdfunding campaign that will be launched early June 2022.
February 21, 2022
On February 17th Minnesota Lakes and Rivers Advocates hosted a webinar where we presented an overview of our recently released report on Boat-Generated Wake Waves. We also discussed our plans for the next phase of research – propeller wash. Over 400 people from across the United States and Canada attended this webinar, and as of today our report has been downloaded from the UMN’s digital conservancy almost 6,000 times. The interest that our report has garnered clearly shows the importance of continuing our research on boat-generated wakes/wash.
https://mnlakesandrivers.org/minnesota-lakes-and-rivers-webinar-draws-national-audience/
February 1, 2022
We are excited to announce that the first report from the St. Anthony Falls Laboratory (SAFL) Healthy Waters Initiative on boat-generated wake waves is now published and available for download. The full report is available via the University of Minnesota’s Digital Conservancy (link below).
This report focuses on characterizing the wake waves produced by four recreational watercraft. Two of these boats are typical recreational watercraft used for cruising, waterskiing, and tubing, and represent boats that have been on Minnesota lakes for many decades. We also studied two wakesurfing boats, newer to Minnesota’s waters. The report discusses the wake waves produced by these boats, including how the wave heights and energy within the waves change with distance from the boat. We hope the data and findings presented in this report are useful for the common goals of developing guidance for shared-use of lakes, education and safety for boat operators and lake users, and the protection and conservation of Minnesota’s most amazing resource - our lakes and rivers.
We want to thank those who provided financial support to this research through our 2020 crowdfunding campaign. Your generosity provided vital resources and allowed us to gather valuable data to begin to better understand how our lakes are responding to recreational boating. This model of funding research is relatively new for SAFL and allowed us to quickly establish this project. It's amazing to think that the crowdfunding was launched in late June 2020 and by September 2020 we had selected our study site, designed and fabricated all our sensor systems, secured boats for the study, and assembled our field team. Data and testing occurred over a very cold and unpredictable October 2020. And over the last year, we’ve been working to process and analyze data and develop this first report.
The report itself is published as a University of Minnesota - St. Anthony Falls Laboratory Project Report. This report has undergone an external technical review by subject matter experts. Two reviewers provided thorough critiques on a draft of the report. Over the last two months, we’ve worked through these reviews and developed the final version of the report.
Our research in this area will continue into the next phase of study, which will focus on the propeller wash generated by recreational boats and on the interactions of waves with lake bottoms, aquatic vegetation, and shorelines. Over the next few months, we will also be developing several proposals to seek funding to support this next phase.
We will continue to post updates through this site as we work to secure funding and develop our research plans.
Contact: For all media requests, please contact Savannah Erdman (erdma158@umn.edu) at University Relations, or the University Relations' main news line at unews@umn.edu.
May 28, 2021
Our team at the University of Minnesota has been carefully working through the boat-generated wave and propeller wash data collected this past October. I know many of you are anxiously waiting for the results to be published, so we thought a progress update was warranted.
First, regarding publication. Over the last 12 months, it has become very clear to us that boat-generated waves and the concerns explicitly associated with the sport of wakesurfing is growing. UMN receives several calls each week about our study or asking if there is research planned for 2021. Inquiries are not limited to Minnesota’s borders, as calls are received from all over the US. There are also important concerns from those that own, sell, or service wakesurfing boats and other recreational watercraft. The fact is that many enjoy Minnesota lakes through tow sports like wakesurfing and want to do so in ways that minimize impacts to our lakes and other lake-users.
Our role at the University of Minnesota remains unchanged, which is to carry out robust, independent research that is published through established academic peer-review processes. Given the importance of our research to all stakeholders, we are taking extra care in the steps leading to publication. At this time, we anticipate self-publishing a relatively comprehensive project report that will be available through UMN’s Digital Conservancy (https://conservancy.umn.edu/). This report will be peer-reviewed by a group of independent reviewers, including scholars not directly affiliated with St. Anthony Falls Laboratory. We believe that our data and findings are strong enough that we also plan to publish this research in an academic peer-reviewed journal as this offers the highest level of academic review. We are diligently working to submit both the report and the first paper with anticipated publications within six to nine months from now. While slower to publish than we’d like, we are confident that this research will have an important impact on stakeholders and decision-makers that are developing solutions toward shared-use and protection of our lakes and river resources.
More details on the 2020 field campaign
We are happy to report that the 2020 field campaign was very successful in terms of the quality of data obtained from the four boats tested (i.e., Larson LXI 210, Malibu Response LX, Malibu VLX, and Malibu MXZ). There are two primary datasets and our plan is that each will be the focus of a peer-reviewed report and academic journal article. The first dataset focuses on the maximum wave height, total wave energy, and total wave power measured for the four boats under various operating conditions and at multiple distances from the data sensors. Our study included operating conditions (e.g., speed, ballast settings, wake wedge/shaper, etc.) that are commonly used in wakesurfing, wakeboarding, water tubing, and water skiing. The second dataset focuses on the propeller wash produced by each test boat and under the selected operating conditions. We are seeing some interesting preliminary results that will help us understand the depth to which the wash produced by the boat propeller projects into the water column. The propeller wash analysis is at an earlier stage than the wave characterization work.
A Wave Monitoring Network
One of our 2020 program goals was to begin developing a cost-effective wave monitoring mast that can be assembled, deployed, and monitored by an established citizen science network. In 2020, we made some progress toward this goal by prototyping a data collection system and a sonic range finder with a total cost under $1000. Because we focused our time on the field study, we paused our efforts on the wave monitoring technology. This summer, however, we will resume efforts and plan to deploy a prototype sensor system at two field sites. We also partnered with colleagues at University of Minnesota, Duluth on a Legislative-Citizen Commission on Minnesota Resources proposal to further develop cost effective lake monitoring sensors. This proposal is currently in review.
Join our network
We realized recently that we do not have email addresses for many of our 2020 research supporters, and the only way I can communicate is through the regular postal service or website updates. I’d like to request that you please sign up for our Healthy Waters Email List (z.umn.edu/SAFLHealthyWaters). Future progress updates will be through email or via our project website.
October 30, 2020
Today was our final day on the lake. We arrived early to start taking down the delicate instrumentation. Later in the day, Three Rivers Park District delivered their large work pontoon for us to use along with a bow mounted crane. A few hours later, all ADCPs and Masts were moved to shore and out of the water. What took three weeks to set up took only one day to tear down.
This is likely my last weekly post as the work will now turn to data review and analysis. I'll post updates as we get into this next phase.
Please sign up here to receive additional updates.
Thanks all for your support of our work!
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October 29, 2020
Thursday was another productive day. The weather was about as nice as we've seen and we were able to complete a full test on a 21-ft direct drive ski boat. This boat is not a wake-surf boat but designed primarily for skiing. One of our test conditions included looking at a third-party wake enhancement device suction-cupped to the boat. Similar devices are available and commonly used to help standard boats create wake-surf conditions.
This was our final day of testing. So thankful to complete testing on four boats and thankful for the hard work of my colleagues and all the help we've received along the way from so many people.
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October 28, 2020
Today we completed testing on a 21-ft Larson 210 sterndrive boat. Weather conditions were favorable and we were able to complete the full range of testing.
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October 21, 2020
Another successful boat evaluation today. A second Malibu Wakesetter was our test subject - this one 21-ft in length. Both boat testing on Monday and today were studied under various operational conditions (ballast, speed, wake enhancements) and different distances from shoreline. Wave heights and water column velocity and turbulence were measured. A preliminary look at the data looks like we captured some great information and will keep us very busy this winter. I'm so grateful to the field team and our boat owners this week for working long days in cold and wet weather!
I'll record here that the 20th brought our first MN snowstorm in the Twin Cities with 6-8" of snow on the ground. The snowfall and low temps was one detail I didn't think through especially well and requires us to spend a fair amount of time care-taking for boats and making sure they aren't damaged by the cold weather, road salt, or icy boat launch conditions. (Note-to-self: In 2021, plan field work during t-shirt and shorts weather...)
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October 19, 2020
Today we completed testing on a 24-ft Malibu Wakesetter wakesurfing boat. The morning was spent deploying sensors and setting up the boat with on-board sensors. Weather was cold with light winds and a light, continuous snow and sleet (not ideal for our computers). It feels great to complete a full test on a large wake surf boat and I'm looking forward to digging into the data.
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Week of October 12, 2020
Our research team is well-seasoned in field and lab research and we are used to dealing with unexpected challenges but this experience doesn't lesson the stress caused by having to watch the days click past and not be able to proceed with our research. October 2020 continues to bring steady winds. We essentially lost a full week this week due to high winds - the highest of which were on Wednesday with gusts up to 30 MPH at times. So, we continue to do what we can from shore focusing on data analysis and optimizing deployment plans.
We took on our second test boat (Malibu Response LX) and have finalized plans for our third and fourth boats. Next week looks like low wind conditions all week however it comes with colder temps and some possible precipitation. We've pushed back our diver and equipment removal to October 31. Next week is a huge week for this project.
20201014_152941.mp420201014_162923.mp4Week of October 5, 2020
Another week of windy weather made progress slower than we wanted and prevented running boats so we turned our focus to improving deployment methods. We placed all turbidity meters into the water and improved our techniques for raising and lower the ADCPs. On Thursday this week we collected our first data on our Larson 210 test boat.
Week of September 28, 2020
We continued to march forward this week with what seems like an endless list of work. Each mast requires a lot of time to hang/mount sensors, secure cables and test performance. One by one, we work through each setup. This week we added our computers and battery systems to masts and worked to deploy our ADCP. We ran our test boat and spent time looking at datasets to make we are capturing the information we want. These are the details that can take months to work out and we really are compressing the work to try and fit this in with remain warm weather.
As we crossed into October we were met with changing weather and strong winds. The beautiful fall colors are backdrop to whitecaps and blue-grey water. We lost several days this week to high winds. I was able to get some work done in the shelter of our south facing shoreline.
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Week of September 21, 2020
This was another full week with early mornings and late nights. The objective of the week was to move all research infrastructure to Lake Independence and set near final location in the water. Monday and Tuesday we finished preparation of three sensor masts and two ADCP pads. Wednesday, we transported this equipment to the research lake and moved to our test shoreline using the Ski-toon. It was a productive day but I did "donate" my phone/camera to the lake bottom. On Thursday our diver, Chris Anderson, joined us for a full day of installation of the five elements into their proper position. Friday, Andy and I continued to finalize mounts, tighten stay-lines, mount floats and buoys and so forth. Long days but nice to see our equipment in the water. Next week we focus on deploying our sensors and starting to run test out with boats.
Week of September 14, 2020
This was a huge week for us with many milestone hit in our setup and at the test site. We completed our ADCP mounting frames, set up our boat-mounted crane, and tested many of these systems our using our facilities at SAFL. On Thursday of this week we also picked up our work pontoon (the Ski-Toon) from our friends and supporters on Christmas Lake. They are letting us use this boat for the duration of our project.
Week of September 7, 2020
Having picked our site, we now focus all energy on finishing up fabrication of equipment that will be placed in the water. We have scheduled our diver for Thursday, Sept 24 and everything is driving to that day. All equipment must be at the site on the 23rd and ready to place in position on the 24th. This is also the first week of class for students and so we say goodbye and thanks to our full-time summer help David Ray and Sam Hirsch.
We are working on many fronts at this point. We are deploying three Masts, which will go in the shallower water and two bottom-mounted platforms for our ADCPs. Ordering, constructing, testing of all this equipment consume our days, which are long but productive.
Setup of Mast A on SAFL lower deck. Testing out stability and performance
Deployment mount for ADCP. (The hardware stores are liking us right now)
Solar panels for keeping batteries charged in the field
Week of August 31, 2020
A full week completed. The pressure to choose a site was on. We toured additional possible research sites on Lake Minnetonka. Our host, Gabriel Jabbour of Tonka Bay Marine was extremely helpful in showing us around different bays and islands where we could set up our study. He also offered use of his marinas to mobilize and base our study. Both lakes offer us great option but in the end I'm choosing to go with Lake Independence for this years study. Why? The main reason is that Lake Independence is a much quieter (less busy) lake, which I have a hunch will be important for our work.
We also had a busy week in the lab with design, fabrication and testing of sensors. Things are coming together.
Week of August 24, 2020
This is the first entry into this activity journal for our 2020 field research campaign on boat wake and propeller wash impacts. Our work has been focusing on design for the field campaign and responding to inquires about the project. Its a bit ambitious to fund, plan and execute a field campaign in only a few month time but we're going to try.
This week I visited Baker Park on Lake Independence in Maple Plain, MN. This lake is a strong contender for our project with a great boat launch, medium size and sandy bottom. Three Rivers Park District has also been very helpful including offering use of some of their facilities at Baker Park.
We are also spending our time in the lab assembling equipment and validating the performance of each sensor at in the flumes and tanks of SAFL.
