9.a Wakes on the Scenic RiverwayWakes on the
Lower St. Croix
National Scenic
Riverway
From St. Croix Falls to the Arcola Sandbar
Page I 1
Executive Summary
Wave action created by boat wakes can have adverse effects on natural resources by damaging riparian
vegetation, eroding river banks and re -suspending sediments. Earlier studies found boat -generated
waves to have a greater erosive potential than either wind -generated waves or currents.
This investigation focuses on the federal section of the Lower St. Croix River from the St. Croix Falls dam
downstream to the Arcola Sandbar. High-speed boat traffic can generate significant wakes on this 23 -
mile -long stretch, may be causing damage to the Scenic Riverway and is inconsistent with management
objectives described in the current Cooperative Management Plan (2002) for this stretch of the river.
A preliminary assessment has identified three broad issues that may be contributing to the frequency of
boats being operated at higher, wake -generating speeds:
1. A probable general lack of awareness on the part of users of the potential for wakes to cause
damage, and of current wake -related restrictions
2. Lack of clarity and inherent inconsistency within wake restriction definitions
3. Apparent uncertainty as to enforcement authority between jurisdictions.
This issue paper is intended to do more than simply define the problem — it seeks to engage natural
resource managers responsible for this stretch of the river, as well as a broader group of
users/stakeholders, in a discussion of potential solutions.
Focusing solely on enforcement will not be effective. Lack of clarity in wake -related requirements and a
general lack of public information contributes to the problem and should be addressed first.
WAKES ON THE LOWER ST. CROIX NATIONAL SCENIC 30 AUGUST 2018
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Contents
ExecutiveSummary.......................................................................................................................................1
Background...................................................................................................................................................
3
The National Scenic Riverway.......................................................................................................................3
WhyWakes Are a Concern............................................................................................................................4
1. Damage to natural resources and property......................................................................................4
2. Potential for conflicting uses............................................................................................................5
3. Public safety......................................................................................................................................5
PreliminaryAssessment................................................................................................................................
6
Lackof awareness.....................................................................................................................................6
Problematicdefinitions.............................................................................................................................7
Jurisdictional uncertainty..........................................................................................................................7
TheOpportunity............................................................................................................................................8
The reasonable person assumption..........................................................................................................8
MovingForward............................................................................................................................................8
1. Clarify wake restrictions....................................................................................................................8
2. Public engagement and education...................................................................................................9
3. Active compliance strategy...............................................................................................................9
Recommendations......................................................................................................................................10
Summary.....................................................................................................................................................10
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Background
Two broad classifications of water are used to describe portions of the St. Croix River: Scenic and
Recreational. The St Croix from headwaters downstream to the Arcola Sandbar is predominantly
designated as Scenic. Use of larger power boats in the stretch of river above the dam at St Croix Falls is
limited due to depth and the presence of hazards such as rocks. Larger power boats can access the
Scenic portion of the Riverway from St. Croix Falls downstream to the Arcola Sandbar, particularly during
periods of high water.
The lower portion of the river, just upstream of Stillwater to the confluence with the Mississippi River, is
the Recreational Riverway, where the use of all manner of boats is unrestricted.
The National Scenic Riverway
The Cooperative Management Plan for the Lower St. Croix River (2002) was developed by the National
Park Service and Departments of Natural Resources in the States of Minnesota and Wisconsin. It
provides the three signatory agencies with guidance in managing the Riverway below the St Croix Falls
dam. This assessment focuses on that portion of the National Scenic Riverway that is within the federal
zone, managed by the National Park Service. Taylor3iSt.CroixFails
The Cooperative Management Plan designates two classes of
s' Pssimiarstate -..
waters in the Scenic Riverway from the St. Croix Falls dam (mile
StateParrkk'°`a B
Scenic
54) downstream to the Arcola Sandbar (mile 31):
Pk— --
Osceola Osceola
➢ The main channel is designated as "Quiet Waters". The
Cedar QUIETWATERS
Bend (mainchanrel)
plan describes management of these waters for
recreational uses that leave the surface of the river
_ake
ihaIwATERs
largely undisturbed. While both motorized and
stsieP sari-
nonmotorized watercraft are allowed, speed is to be
kept low.
Cron'
St.
St. Croix
➢ Backwater areas in this same stretch of river are
61 cmixi:iands
Wildlife An �a
designated as "Natural Waters". The management
sa MODERATE
objective for this class of water is for watercraft speeds
1 p
Somerset RECREATION
35 (main charnel)
to be low and the surface of the water undisturbed.
64 NATURAL WATERS
-•--•- Federal Zone -��ckwarersl___-
----
Stillwater S`tate�°^e
This Scenic portion of the St. Croix is bounded on the north by '
an impassable dam. Boat traffic from the south is restricted by
the zebra mussel access control point (quarantine boundary) at Figure 1 The 23 -mile -long area of interest
the Soo Line High Bridge (mile 28.5); during periods of low water, shallow depths at the Arcola Sandbar
effectively restrict access northward by larger vessels. As a result, users operating larger boats access
this stretch of river at one of seven public boat launches.
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Why Wakes Are a Concern
There are three reasons excessive wakes caused by high-speed boat traffic are a concern.
Damage to natural resources and property
An interagency study' evaluated the effect of boat -generated wakes on shoreline erosion and
sedimentation on the St. Croix River below the Arcola Sandbar. That study identified a sediment
mobilization threshold. Boat wakes less than 0.4 ft. in height near shore resulted in little erosion and
very limited amounts of sediment
mobilization, "whereas wave height
greater than the threshold mobilized
orders of magnitude greater amounts of
sediment"'. This study also considered
natural causes of erosion such as wind -
driven waves and river current speed. The
study found that the River is partially
sheltered from most winds, and that
"wind -generated wave heights were much
less than the 0.4ft mobilization threshold"'
The study also noted that near -shore
channel bottom velocity during normal
flow was typically below the level
necessary to erode sediments4. The
conclusion is that neither of these natural
causes could explain the amount of
erosion that was observed and was
ST. CROIX RIVER RECREATION STUDY
AVERAGE SEDIMENT MOBILIZED
11,
C
300
CD
0
w
m 200
0
LU 100
a
w
0
0 0.5 1 1.5 z
WAVE HEIGHT (feet)
attributed to boat wakes. An earlier stud y5 Figure 1 Sediment mobilization increases sharply when wave height
by MN DNR similarly identified wakes exceeds 0.4 ft(=5in).
generated by recreational boats as the
predominant cause of shoreline erosion on the Mississippi River.
It is worth noting that the interagency study focused on approximately five miles of river downstream of
the Arcola Sandbar. This sandbar occurs at the confluence of the St. Croix and Apple Rivers, which slows
current, resulting in deposition of sand particles. The particle size of sediments in the study area would
be expected to be larger than the finer sediments found in the main channel (Quiet Water) above the
Arcola Sandbar, and the fine silt of "Natural Water" backwaters. Finer particles would be more easily
eroded and suspended as sediments in the water column.
The frequency of use by larger boats operated at higher speeds in the Scenic Riverway is somewhat
limited during periods of lower water, thus potential damage is mitigated by the lower water levels that
expose less erodible materials. In contrast, high water creates greater access for larger boats and
' St. Croix River Shoreline Studies 1995-2000, May 2001
" Ibid, Page 6.8
' Ibid, Page 8.6
4 Ibid, Page 9.8
5 Johnson, S.B. 1994. Recreational Boating Impact Investigations, Upper Mississippi River System, Pool 4 US Fish
and Wildlife Service Special Report 94-5004
WAKES ON THE LOWER ST. CROIX NATIONAL SCENIC 30 AUGUST 2018
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motors, and exposes flooded riparian zones to an increased risk of erosion. Excessive wakes can also
cause damage to personal property and shoreline structures such as docks, landings, and moored boats.
Increasing use by boats with deep -V hulls and high horsepower motors, together with projections for
increased peak summer rainfalls and subsequent high-water events, suggest that the potential for wake -
related damage will continue to increase.
Fine sediments are suspended in the water column for longer periods than course sand, and typically
create a plume that may persist along the river bottom for some distance out from shore. As a result,
turbidity increases, which reduces light penetration in near -shore water, to the detriment of benthic
plants. The suspended sediments may also carry excess phosphorous, which is a concern in the lower
riverway (e.g., Lake St. Croix) as it can trigger algae blooms. When these sediments eventually settle out,
they may blanket benthic organisms.
The Scenic Riverway is a National Park, and the inherent integrity of the natural resources being
managed should be preserved for future generations.
2. Potential for conflicting uses
Operation of a powerboat is not inherently inconsistent with management objectives for recreational
use in the Scenic Riverway. In fact, the definition of "Quiet Waters" includes specific reference to
operation of motorized watercraft at low speed. However, operation at speeds sufficient to cause
damaging wakes conflicts with other non -motorized and passive forms of recreation.
Noise levels generated by some types of boats also can be a source of conflict between uses and users.
An example is the increased use of shallow draft boats equipped with "mud motors". This type of craft
can operate at high speed in shallow water and, unlike outboard motors where exhaust is muffled as it
exits underwater, mud motors typically exhaust above the water surface. The result is that they tend to
be much louder than outboard motors.
The area of river impacted by recreational activities varies by type of use. A wader might use an area of
about his or her footprint; a canoe or kayak perhaps about twice its width and 3 or 4 times its length,
and a slow-moving power boat something larger but still a limited area. In contrast, a fast-moving boat
will occupy and disturb a much larger area due to both its wake and significantly longer pathway of
disturbance.
The principle of multiple use has long been embraced by recreation managers. It is also recognized that
not all uses are compatible' with each other. The current level of tension between riverside
landowners, passive recreational users, and power boaters was clearly demonstrated at a recent public
hearing regarding Log House Landing near Scandia.
3. Public safety
Many of the existing general boating regulations are in place because of concerns for public safety.
Excessive wakes generated by the high-speed operation of power boats may cause wakes capable of
swamping or capsizing small, human -powered watercraft. Operating a powerboat at high speed in this
stretch of the river also creates risk of striking navigational hazards such as the many snags,
"deadheads" and sandbars. It may also create a hazard to swimmers and waders.
' e.g., Snowmobiles and cross-country skiers, off-road motorized vehicles and hikers, etc.
WAKES ON THE LOWER ST. CROIX NATIONAL SCENIC 30 AUGUST 2018
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Preliminary Assessment
This assessment began with an initial observation that there appeared to be a relatively high level of
non-compliance with wake -related restrictions in the Scenic Riverway. The assumption was that this
was due to a lack of awareness of wake restrictions among users. The obvious question then is: Why
would that be the case?
Lack of awareness
A survey of the seven public boat landings in the Scenic Riverway was conducted in October 2016. Table
1 reveals a surprising lack of information related to wake restrictions at these public access sites. To be
clear, this survey was completed in 2016, nearly two years prior to this white paper. The seven launch
sites have not been reassessed, and some additional signage has since been added.
Table 1 Results from informal survey of signage at public landings in the Scenic River, October 2016
Wake -related
Information posted y_
N
tM m
at public landings, L
d
Oct. 2016 C
Z
L 2
W
C
c
U J
_
N
O J
_j E
o c m
= J O
c
N J
No Wake River wide �����®
•
No wake north of ��
•
�®
Arcola
Slow speed, < plane
No wake Min 100' of
shore
wake Min 100' of
���®
•
paddlers
pa
wake w/in 100' o
��®®
•
swimmers
swimmers
wake in marked
��®®
•
(buoys) areas
(b
Stillwater Gauge •
>683'
��®�®
personal ��®����
watercraft
•
Some other sources of wake -related public information available to users are equally inconsistent. This
assessment suggests that it is not easy for the public to find accurate wake -related information for the
Scenic Riverway on relevant web sites, nor are existing regulations easily located. If users are unaware
of wake restrictions, it is unreasonable to expect a high level of compliance.
WAKES ON THE LOWER ST. CROIX NATIONAL SCENIC 30 AUGUST 2018
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Problematic definitions
Regulations in Minnesota and Wisconsin provide useful definitions for both classes of water defined for
the Scenic Riverway in the current Cooperative
Management Plan for the Lower St. Croix River:
➢ Slow speed' means
operation of a motorboat at
a leisurely speed, less than
planing speed, whereby the
wake or wash created by the
Obviously
motorboat is minimal. This
non-compliant Planing Speed
is consistent with the intent
for "Quiet Waters" in the
=
_
main channel from St. Croix
Falls to the Arcola Sandbar.
W
Significant Wake, et less than
g f y
➢ Slow -no wakes means
2
'
operation of a motor boat at
W
Planing Speed
Y
the slowest possible speed
Q
necessary to maintain
Minimal Wake, "Quiet Waters"
steerage, not to exceed 5
mph. This is consistent with
No Wake, -
the intent for "Natural
SPEED THROUGH WATER
Waters in the backwater
areas. Figure 2 The relationship between boat speed and the wake generated
These definitions have been confirmed as applicable in a Federal Court case'. There are also Federal and
State regulations that establish a "no wake" zone within 100 feet of shore. Since the backwater
channels are typically less than 200 feet wide, this restriction is particularly relevant to Natural Waters.
However, there is some confusion with the definition of "slow speed". First, some references to wake -
related regulations applicable to the Scenic Riverway use an abridged definition that simply focuses on
the phrase "less than planing speed". Ignoring the additional requirement that the wake or wash
created be minimal sets up inherent conflict within the definition itself. The size of wake generated at
less than planing speed can be significant. Figure 2 illustrates this point.
Jurisdictional uncertainty
While the Scenic Riverway is within the Federal Zone, several agencies share responsibilities for
enforcement of boating regulations on this stretch of National Scenic Riverway including:
• National Park Service, Rangers
• Minnesota DNR, Conservation Officers
• Wisconsin DNR, Conservation Wardens
• County Sheriffs in St. Croix and Polk counties WI, and Washington and Chisago counties in MN
' MN Rule 6105.0320 subpart 5 and Wl NR5.32(4)
8 MN Rule 6105.0320 subpart 4 and WI NR5.32(3)
' St Croix Waterway Ass'n v. Meyer, 942 F. Supp 434 (D. Minn. 1996)
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While the current Comprehensive Plan establishes intent that "existing water use enforcement roles will
continue, and the three agencies will provide staff for on -water law enforcement"10 there appears to be
some uncertainty as to the regulatory authority to enforce wake -related regulations. Additionally, there
is concern over committing already limited resources to enforcement of wake -related regulations in the
Scenic Riverway.
Enforcement can be a polarizing issue. Before enhanced enforcement options can reasonably be
considered, it will be important to raise public awareness of the existing rules relating to wake -
generating activities within the Scenic Riverway.
The Opportunity
When the topic of wakes arises, the initial reaction often is to simply focus on enforcement, or the lack
thereof. However, this preliminary investigation has identified several issues that need to be addressed
before enforcement can be a prudent and practical component of any solution to the problem of
excessive wakes.
The reasonable person assumption
Most people, given an understanding of an issue, will make good decisions. At most boat launches
capable of handling a trailered power boat within the Scenic Riverway downstream from St Croix Falls
there is little to no mention of wake issues. Riverfront property owners that keep powerboats on this
stretch of the river may also be unaware of wake -related concerns. In other cases, property owners
may be fully aware of the issue of wakes and be supportive of an initiative intended to raise awareness
of these concerns with the boating public. It is reasonable to expect that many river users will comply
with wake rules if they were aware of them and understood the reasons for them - protecting the river
from wake damage, which can adversely affect the fishery, recreational uses, and water quality.
There is also a need to clarify wake -related regulations so that responsible users can easily and reliably
determine whether their operation of a power boat is compliant with the recreational objectives for the
Scenic Riverway as described in the Comprehensive Management Plan.
Once these issues have been addressed, it is reasonable to expect that incidents of excessive wakes
would be much less common, and those that did occur may be egregious enough to be obvious
violations warranting enforcement action.
Moving Forward
There are three general areas that need to be addressed:
1. Clarify wake restrictions
There is no need for new wake -related regulations — those currently in place are adequate. However,
they need to be clarified. This can be done with the development of "safe harbor" statements. The
"Cooperative Management Plan, Lower St Croix National Riverway, January 2002, Summary, Page iv.
WAKES ON THE LOWER ST. CROIX NATIONAL SCENIC 30 AUGUST 2018
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intent of safe harbor statements is to give the user some simple ways to determine that their operation
of a power boat is compliant with the intent of the regulations.
Preliminary work has already begun to develop potential safe harbor statements. A poster has been
presented at a limited number of stakeholder meetings, and feedback was solicited. Table 2 presents
some preliminary ideas.
Table 2 Examples of potential safe harbor statements
You know you are compliant with wake regulations if....
✓ The wake your boat generates is less than the height of a 12 -oz. beverage can (0.4ft)
✓ There are no breaking waves in your wake
✓ There is no white water in your wake
✓ No or minimal back wash along the shore due to your wake
✓ Docks and other boats do not rock excessively
✓ Other river users aren't affected by your wake, they don't have to alter what they are doing to
avoid wake -related problems.
While the current Cooperative Management Plan contemplates the need for "new watersurface use
rules or regulations"", this strategy would not require any change to existing regulations. Rather it
represents a way to address the need for better compliance with current policy by simply improving
clarity and comprehension.
2. Public engagement and education
A public engagement and public education strategy should be developed. There is a need to engage
river users and other stakeholders in the process of developing safe harbor statements, and in
developing effective means of providing information to users. Adding wake -related information to
signs at landings would be a first step, but public education efforts should go beyond simply improving
the signage at the landings.
3. Active compliance strategy
The law enforcement community should be engaged in developing a proactive strategy to increase
compliance. This should not be limited to enforcement (writing tickets). Enforcement personnel would
likely have some good ideas on how to frame the opposite of the safe harbor statements (e.g., "You
know you are in violation if you see..."). Not only would this help inform users, it would also help
enforcers define what constitutes non-compliant behavior that would warrant a warning or citation.
11 Cooperative Management Plan, Lower St. Croix National Riverway, January 2002, Summary, Page iv.
WAKES ON THE LOWER ST. CROIX NATIONAL SCENIC 30 AUGUST 2018
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Recommendations
The following steps are offered as a means of addressing the issues identified in this assessment paper:
✓ The Lower St. Croix River Management Commission should authorize a stakeholder study group
charged with a review of the issues identified in this white paper with the goal of developing a
plan with recommendations that address concerns.
o The process should be inclusive of stakeholders with interest in the Scenic Riverway and
include natural resource managers from the relevant agencies as well as land owners
and user groups.
o The primary focus should be on public education intended to raise awareness of wake -
related issues and restrictions within the Scenic Riverway. The goals should include
clarifying why and what the rules are, as well as determining the best ways to "get the
message out".
o The plan should include actionable recommendations and schedules, as well as
estimates of required resources.
✓ Initiatives that come from the process should complement other NPS and DNR interests and
activities (e.g., boater safety, awareness of aquatic invasive species, water quality concerns).
✓ The law enforcement community should be engaged in developing guidance on determining
what constitutes clear violations of the existing boat rules on the Scenic Riverway, and to
develop enforcement strategies that could be used once the public has been adequately
informed. Enforcement is envisioned as a later step in the process and would focus on the most
egregious violations.
This initiative will take some time. The study that resulted in this white paper began nearly two years
ago. The process envisioned to address these issues may require an equal amount of time. The issues
identified are not going away on their own. It will be important to address them in a thoughtful and
thorough manner.
Summary
The use of motorized watercraft can be consistent with the management objectives for the Scenic
Riverway. However, excessive boat wakes on the Scenic Riverway can create problems including
damage to water quality, natural resources and personal property. Higher -speed boat traffic may also
create conflicts with other, low -intensity uses of the river. This initial assessment identified a number of
issues and opportunities. Simply focusing on enforcement will not be effective.
Lack of clarity in wake -related requirements and a general lack of public
information contributes to the problem and should be addressed first. alt.-
ST. CROIX
\
AMASTER WATERSHED
STEWARDS
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