HomeMy WebLinkAbout5.13_6590 Davis_Manmade Wetlands
161 W HALEY SPRINGS RD | SUITE 101 | BOZEMAN, MT 59718 | (406) 587-2781
Professional Consulting Engineers and Land Surveyors
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April 7, 2025
City of Bozeman- Community Development Department
PO Box 1230
Bozeman, MT 59771
Attn: Susana Montana - Senior Planner, Community Development
Alicia Paz-Solis, PE- Development Review Engineer
RE: S&S Davis Apartments – Site Plan Submittal
Wetland / Section Line Ditch Narrative
Bozeman, Montana
Dear Susana & Alicia:
Under Division 38.610 Wetland Regulations of the Bozeman Municipal Code, Section 38.610.010 states that
“….The provisions contained in these regulations do not apply to wetlands created by a wholly manmade
water source used for irrigation purposes or stormwater control.” This narrative and supporting
documentation support the claim that the wetlands found at 6590 Davis Lane are in existence due to the
interaction of a wholly manmade water source (Section Line Ditch) and the historic Northern Pacific railroad
embankment. After reviewing the area on-site and considering the relevant historical and hydrological
factors, I believe this classification is accurate and reflects the significant role that human intervention has
played in shaping the current state of the wetland ecosystem on the property.
The Section Line Ditch is located in Gallatin County within the western portion of the City of Bozeman, and
roughly follows the section line between Sections 34 and 35 near the subject property. Section Line Ditch is
a manmade ditch constructed around the turn of the 20th century and has been providing irrigation water to
numerous water-right-users along the ditch for over 100 years. In addition to providing water to the water-
right-users, Section Line Ditch is also used to convey stormwater runoff to ease flooding (Habitat/Wetland
Assessment Report “Section Line Ditch”, R. LaFond, 2001). The irrigation channel has a status of “No
Waterway” per the U.S. Geological Survey (Gallatin County Environmental Health mapper) and is used to
convey irrigation water from the Farmer’s Canal irrigation system.
The headgate for the Section Line Ditch is located on Farmer’s Canal just south of Main Street. The
headgate for the Farmers Canal is located on the east side of the West Gallatin River near Gallatin Gateway.
Section Line Ditch follows the section line for approximately 3.5 miles to the north where it merges with
Cattail Creek, and ultimately travels northwest and empties into the East Gallatin River just north of the
Bozeman Yellowstone International Airport. In an average year, water is diverted to Section Line Ditch from
mid-May through mid-September.
With the Gallatin River and East Gallatin River both being classified as waters of the U.S., they are
considered Jurisdictional under Section 404 of the Clean Water Act. This is a consideration since Section
Line Ditch contributes flow to the East Gallatin River, rather than totally dispersing flow on irrigated fields.
The ACOE jurisdictional determination has been provided with the application documents, and we are
currently coordinating with the ACOE on the 404 permit.
Per a Class I cultural resource assessment conducted by Hope Archaeology, Inc., the Northern Pacific
Railroad route in the project vicinity was constructed in 1883. The railroad line was abandoned in 1956 and
dismantled in 1957.
A 36” diameter culvert was installed beneath the railroad berm to convey the water from the Section Line
Ditch. The southern invert of the culvert (invert in) is elevated approximately 0.8’ (per field survey
measurements) above the bottom of the Section Line Ditch channel. The elevation of the culvert results in
ponding of water on the south side of the railroad berm.
Letter to City of Bozeman
Re: S&S Davis Apartments
Wetland / Section Line Ditch Narrative
April 7, 2025
Page 2 of 2
L:\213601\_CoB Site Plan\Response #3\Wetlands\Davis Jr_Manmade Wetlands-bri.docx
The interaction between the irrigation ditch and the railroad berm likely created specific hydrological
conditions that are not natural to the original landscape. The introduction of artificial water channels,
combined with the constructed railroad berm, would have altered the flow of water, leading to the creation of
wetland-like conditions in what would otherwise be a non-wetland area. The ditch, by channeling water into
the area, has influenced the local hydrology in such a way that it has effectively created a wetland habitat,
even if it is not a natural wetland. Although the groundwater is high in this area (as It is throughout the NW
side of Bozeman) the groundwater measurements range from approximately 1.5 feet below ground surface
during the peak season to between 2.5 and 4 feet for the majority of the year. We do not see a direct
correlation between observed groundwater measurements leading to increased flow rate in the Section Line
Ditch.
Additionally, wetlands are typically defined not only by the presence of water but by the influence of human
activities on the water flow, soil structure, and plant life. In this case, the irrigation ditch directly impacts the
area's hydrological regime and has shaped the vegetation and habitat characteristics typically associated
with wetlands. As such, it is reasonable to classify the area as manmade due to the distinct changes induced
by the irrigation infrastructure.
The historical role of the railroad berm should also be considered in this context. While the berm itself may
have been built for transportation purposes, its intersection with the irrigation ditch likely further altered the
natural landscape, leading to the current wetland condition. This reinforces the idea that the wetland was
shaped by human intervention rather than occurring purely through natural processes.
Given these factors, I believe the classification of the water source and associated wetlands as manmade is
not only accurate but important for future land-use and environmental management decisions.
Understanding the wetlands in the context of their human origins allows for a more informed approach to
their preservation and management, particularly in areas where human infrastructure continues to play a
significant role in shaping the local ecosystem.
Thank you for your attention to this matter. I appreciate the opportunity to provide input and trust that this
perspective will be taken into consideration in the ongoing assessment of the area. If for any reason you
have any questions, or need any additional information during the review of this project, please feel free to
give me a call at 587-2781 or send an email to bmegaard@hyaliteeng.com.
Sincerely,
_____________________________
Brett Megaard, P.E.
Senior Project Manager
Cc: File: 213601
Owner