Designing Riparian Buffers For North Field

Designing Riparian Buffers for Northfield - Guidelines and Suggestions for the Northfield Comprehensive Plan Revision

Contents: Summary Context Riparian buffer proposal Specific guidelines for Spring Brook (Rice) Creek References Cited and other references Summary of protection resources available to landowners and municipalities Maps showing buffers in the Spring Brook Creek/Heath Creek corridor Prepared by: Oona Rokyta, Eric Shoemaker, Jacob Limmer, Greg Rafert, Lauren Miller, Arijit Guha, Noah Brenner, all Carleton students Assisted by: Mary Savina, Professor of Geology, Chris Robbins, Northfield citizen, Lisa Lukis, Cannon River Watershed Partnership November 16, 2000

Summary The process leading to the comprehensive plan revision is an opportunity to recognize and protect the natural resources such as streams within the Northfield expansion area. There is an abundance of scientific and technical literature documenting the ways that riparian  buffer zones protect streams, water quality, fish and animal habitat. (see list below for three  excellent web resources). We have developed seven criteria to guide the establishment of riparian  buffers along Cannon River tributaries: ~Criterion 1: Identify the floodplain and include all of it in the riparian buffer zone. ~Criterion 2: Incorporate current woodland areas in the buffer zone as much as possible (and consider planting buffers into trees). ~Criterion 3: Protect steep slopes above the floodplain in the buffer zone and include some distance of higher, flatter ground in buffer. ~Criterion 4: Include stream tributary drainages, swales, and springs in the buffer zone. ~Criterion 5: Incorporate riparian wetlands in the buffer zone. ~Criterion 6: No storm water should be channeled through buffer zones or directly into the streams. ~Criterion 7: Educate landowners, developers, and everyone else through zoning ordinances and other means Using these criteria, we recommend that the Northfield comprehensive plan map and text establish a minimum riparian buffer width of 75 m (250 ft.) on each side of the tributary streams with a wider zone as needed to fulfill the criteria completely. Buffers should be planted in trees and dense grass with deep roots. Riparian buffers are compatible with a variety of passive recreational uses. Special consideration should be given to the Spring Brook (Rice) Creek, the only cold-water trout stream in Rice County. In addition to strict adherence to the criteria above, the stream channel itself should not be affected in any way by development and the spring inflow should be protected. Many organizations have created grants and other financing programs to assist communities and private landowners with the costs of buffering projects. The organizations with the most available money include the Environmental Protection Agency, the US Department of Agriculture, the National Fish and Wildlife Service, and the Minnesota Department of Natural Resources and the Nature Conservancy. Grants normally cover 25-100% of the total cost of the project. Three useful web references: Palone, Roxane and Albert Todd, eds., 1998, Chesapeake Bay Riparian Handbook: A Guide for Establishing and Maintaining Riparian Buffers: USDA NA-TP-02-97, 481 p. (The handbook is downloadable as a .pdf file from http://www.fs.fed.us/na/morgantown/frm/water/riphbk/riphbkdl.htm) Schueler, Tom, 1995, The Architecture of Stream Buffers: Watershed Protection Techniques, v. 1, 8 p. (available on-line at http://www/pipeline.com/~mrrunoff/buffer.htm and at http://www.cwp.org/) University of Maryland web site on riparian buffers: http://www.riparianbuffers.umd.edu/

Context Northfield is currently revising its comprehensive plan, anticipating the changing needs of the City over the next 20 years. The planning process leading to the revision is an opportunity to recognize and protect the natural resources within the City limits and in the directions that the City is likely to grow. One of these natural resources is the waterways, including the Cannon River and its tributaries. Water quality in the Cannon River watershed - and throughout the Upper Mississippi River basin affects habitat both locally and globally. High nutrient levels throughout streams in the Upper Mississippi are now known to contribute to hypoxia in the Gulf of Mexico (Downing et al., 1999). The water quality in the Upper Mississippi is controlled by the water quality in the major tributaries such as the Cannon River. Water quality on the Cannon River, in turn, is controlled largely by the water quality in its tributaries, streams like Heath Creek, Prairie Creek, Wolf Creek, Spring Creek and Spring Brook (or Rice) Creek that flow through or near Northfield. Although these streams are all unique, one of them, Spring Brook (Rice) Creek is a coldwater stream that supports a native population of brook trout. The major tributaries of the Cannon River that drain the area west of the Cannon may have initially  been subglacial conduits draining the Des Moines Lobe glacier (Patterson and Hobbs, 1995). The  valley landforms of Heath Creek and Wolf Creek  ­ wide floodplains bordered by short steep slopes  ­ formed during this period of high discharge from the melting glacier.  The area between these two  valleys now drains into Spring Brook Creek. These valleys have wide floodplains  bordered by  relatively steep slopes, features largely inherited from the glacial past. There is an abundance of scientific and technical literature documenting the ways that riparian  buffers protect streams, fish and animal habitat.  Regions such as the Chesapeake Bay drainage  basin have been particularly advanced in designing buffers appropriate for urban and agricultural  land. In the rest of this document, we try to define guidelines based on some of these studies to help  the City of Northfield determine appropriate locations and widths for riparian buffers along its  streams. 

Riparian Buffer Zone Proposal We use the term "riparian buffer" to mean a vegetated zone of variable width near the stream channel, managed to reduce the impact of adjacent development on the stream, its banks and its floodplain and to preserve stream integrity. Among other benefits (Palone and Todd, 1998 and other references listed below), riparian buffers help to prevent erosion, preserve channel integrity, protect water quality by filtering agricultural and urban run-off and sediment (e.g. Komar and Magner, 1996), provide effective passive flood control and provide habitat for wildlife. Some workers consider a buffer network a "stream right-of-way," a useful approach to planning (Schueler, 1995b). For maximum effectiveness, buffers should be planted in trees and dense grass with deep roots. The US Department of Agriculture has developed a three-zone buffer model with forest closest to the stream (zones 1 and 2) and dense grass filter strips furthest from the stream (zone 3) (Palone and Todd, 1998). Buffers should be continuous along the stream; breaks in buffers allow runoff and sediment to cross into the stream corridor (Schueler, 1995b; Weller et al., 1998). Riparian buffers are compatible with a variety of passive recreational uses, including hiking, birdwatching, and fishing. In some instances buffers may be wide enough to accommodate paved trails. Riparian buffers along creeks in Northfield should probably be publicly owned but may be used in part as park dedication during development. Note: When establishing buffer zones, it is important to keep in mind the variability of guidelines depending on the specific geography of the area. Zones should be determined not by a pre-set standard distance from the water’s edge, but by physically pertinent aspects of the area: natural boundaries of sensitive areas such as flood plains, sloping areas, wetlands and established habitats. Criteria for buffer establishment in the Northfield urban area: ~Criterion 1: Identify the floodplain and include all of it in the riparian buffer zone. The entire floodplain must be included in the buffer zone because it is one of the most vulnerable areas around the stream, and the floodplain and stream interact closely with one another. A floodplain must have some cover protection and must be an unpolluted area or it will erode and pollute the stream when it is flooded. Many communities require the buffer zone to include all of the 100-year floodplain; a minimum base width of at least 100 feet is recommended (Schueler, 1995a; Smith and Hellmund, 1993). ~Criterion 2: Incorporate current woodland areas in the buffer zone as much as possible (and consider planting buffers into trees). Forests make the best buffer zones for a variety of reasons (see attached tables from Schueler, 1995b and Agroforestry Notes AF-4, 1997, cited in Tjaden and Weber, FS733): ~They are probably the most effective groundcover for preventing bank erosion, blocking wind and intercepting rainfall, and holding dirt and sediment. ~Trees, as well as other vegetation, play an important role in nutrient uptake, not only from water entering the stream from the side, but water coming from upstream. ~Shade helps to keep the water cool and decreases temperature fluctuation. This function is particularly important for preservation of species that require cold water.

~Deep roots stabilize the stream bank. Root systems also slow water flow and keep the soil porous, so water moves more slowly and is better absorbed. This reduces flooding and allows the water to be slowly filtered before it hits the stream, as well as letting some into the groundwater. ~Fallen branches slow water and provide good habitats for fish and invertebrates. It is essential to the stream ecosystem functions of the riparian buffer that this "large woody debris" remain in the stream channel. ~Trees are a pleasant environment for both wildlife and humans; they provide good habitat for a variety of animals and corridors for animal migration and human trail systems. ~Criterion 3: Protect steep slopes above the floodplain in the buffer zone and include some distance of higher, flatter ground in buffer. Steep slopes are especially vulnerable to erosion, as are the areas immediately above steep slopes. This criterion also has direct benefits for farmers as it helps prevent valuable topsoil from washing away, but is also necessary to protect streams in developed areas from excess sediment. All undevelopable steep slopes should definitely be included, as these are extremely prone to soil loss when not protected by groundcover. Schueler (1995a, 1995b) recommends including "all undevelopable steep slopes (>25%) and steep slopes (5% to 25% slope at four additional feet of slope per one percent increment of slope about 5%)" (Schueler, 1995b, p. 3). Note that the present Northfield comprehensive plan identifies undevelopable steep slopes as those over 18%. Protecting part of the higher, flatter ground above the steep slopes in the buffer helps to slow runoff and prevent it from concentrating as it crosses the buffer. ~Criterion 4: Include stream tributary drainages, swales, and springs in the buffer zone. Protecting headwaters and other water sources will offer the best water quality protection for the water system as a whole (Smith and Hellmund, 1993). In addition, any areas where waterways connect with one another are critical areas for wildlife. ~Criterion 5: Incorporate riparian wetlands in the buffer zone. Wetlands are areas flooded or saturated with water, having hydric soils and supporting or able to support aquatic vegetation. Wetlands are also tend to be excellent filters, their vegetation absorbing high quantities of sediment, minerals and nutrients. ~Criterion 6: No storm water should be channeled through buffer zones or directly into the streams. Buffer zones can only do so much. Usually, a buffer can only treat run-off from less than 10% of a stream’s contributing watershed because the other 90% of the water becomes concentrated into the storm water system (Schueler, 1995b). Water quality can be greatly affected (both by toxic chemicals and excessive nutrients) if storm water from developed areas is allowed to flow directly into the streams. Water quality in Heath Creek and other non-trout creeks should be at least maintained, if not improved. ~Criterion 7: Educate landowners, developers, and everyone else through zoning ordinances and other means Develop additional criteria to reduce the effects of concentrated and other drainage from developments through the buffer: avoid storm sewers, seek infiltration areas or other alternatives, limit impervious surfaces to <10% near buffer zones, avoid chemical use, etc. Make sure these more specific criteria are listed in the environmental management section of the comprehensive plan, the Northfield zoning ordinance and are made known to developers, realtors and the general public. Using these criteria, we recommend that the Northfield comprehensive plan map and text establish a minimum riparian buffer width of 75 m (250 ft.) on each side of the streams with a wider zone as needed to fulfill the criteria completely. This buffer should be included as "open space" and

"wetland" on the comp plan map and legend. The "environmentally sensitive overlay" area should extend well beyond the margins of the riparian buffer (as it does in the most recent comp plan drafts). Specific Recommendations for the Spring Brook/Rice Creek Watershed Having discussed some of the methods and rationale behind riparian buffer zone construction, we would now like to turn to some specific recommendations about the possible implementation of riparian buffer zones on the Spring Brook/Rice Creek watershed. Given the strong possibility that this watershed will be developed in the coming years, and the sensitivity of the cold-water ecosystem, we feel that it is incumbent upon the city of Northfield and other involved parties to begin to design the riparian buffer zones on this watershed (Spring Brook Committee Report, 1999). Thinking ahead on this issue may help to ensure proper planning of buffer zones that both meet the needs of preserving fragile ecosystems while at the same time allowing for limited development. Our recommendations for this watershed are as follows: 1) Riparian buffer zones in this watershed should be inclusive of the entire floodplain, the steep slopes adjacent to the floodplain (back to the ridgeline) and some distance beyond this point. No permanent structure development should take place within the floodplain limits. 2) The construction of buffer zones in this watershed should also include substantial streamside revegetation. This helps to cool the water, preserving the ecosystem for native brook trout, and mitigating for some of the negative warming effects that are usually associated with development. 3) The stream channel itself should not be affected in any way by development. This includes the construction of ponds, channelization, and the building of culverts. 4) Special attention should be paid to the fact the valuable coldwater ecosystem that exists in this watershed is dependent on extensive spring inflow in the lower section of the creek. Any development that takes place in this watershed should be mindful of this fact. Efforts should be made to limit the construction of impermeable surfaces or anything else that may adversely affect the functioning of these springs. References Cited: Downing, John A. and five others, task force members, 1999, Hypoxia in the Gulf of Mexico: Land and Sea Interactions: Council for Agricultural Science and Technology, 44 p. Available at: http://www.cast-science.org/pdf/hypo.pdf Komor, S. C., Magner, J. A., 1996, Nitrate in groundwater and water sources used by riparian trees in an agricultural watershed: A chemical and isotopic investigation in southern Minnesota: Water Resources Research, v. 32, p. 1039-1050. Palone, Roxane and Albert Todd, eds., 1998, Chesapeake Bay Riparian Handbook: A Guide for Establishing and Maintaining Riparian Buffers: USDA Forest Service, NRCS, and Cooperative State Research, Extension and Education, NA-TP-02-97, 481 p. (The handbook is downloadable as a .pdf file from http://www.fs.fed.us/na/morgantown/frm/water/riphbk/riphbkdl.htm) Patterson, Carrie J. and Howard C. Hobbs, 1995, Surficial Geology, Rice County Geological Atlas: Minnesota Geological Survey, County Atlas Series, Atlas C-9, Part A, plate 3.

Schueler, Tom, 1995a, Site Planning for Urban Stream Protection: Silver Spring, MD, Center for Watershed Protection, 320 pp. Schueler, Tom, 1995b, The Architecture of Stream Buffers: Watershed Protection Techniques, v. 1, 8 p. (available on-line at http://www/pipeline.com/~mrrunoff/buffer.htm) Smith, Daniel S. and Paul Cawood Hellmund, ed. 1993, Ecology of Greenways. Minneapolis, MN, University of Minnesota Press, 222 pp. Spring Brook Committee Report, 1999, 12 p. plus appendices. Tjaden, Robert L. and Glenda M. Weber, Riparian Buffer Management: An Introduction to the Riparian Forest Buffer, Fact Sheet 724. http://www.agnr.umd.edu/ces/pubs/html/fs724/fs724.html Tjaden, Robert L. and Glenda M. Weber, Riparian Buffer Management: Riparian Buffer Systems, Fact Sheet 733. http://www.agnr.umd.edu/ces/pubs/html/fs733.html Weller, D. E., Jordan, T. E., Correll, D. L., 1998, Heuristic models for material discharge from landscapes with riparian buffers: Ecological Applications, v. 8, p. 1156-1169. Additional reference used: Black, Peter E., 1991, Watershed Hydrology: Englewood Cliffs, NJ, Prentice-Hall, Inc., 408 pp. Some additional sources/good websites for basic information on riparian buffers and other waterway issues: The first three sources are particularly valuable because they deal with riparian buffers in the context of urban development as well as agriculture: Center for Watershed Protection: http://www.cwp.org/ Site has several publications relevant to riparian buffers, including Schueler, 1995b, The Architecture of Stream Buffers, a condensed excerpt from Site Planning for Urban Stream Protection (see References Cited). The manual contains practical guidance on the design of stream buffers, cluster development, narrower residential streets and green parking lots.) Chesapeake Bay ~ downloadable handbook: http://www.fs.fed.us/na/morgantown/frm/water/riphbk/riphbkdl.htm University of Maryland: http://www.riparianbuffers.umd.edu/ The following sources deal mainly with the design and impact of buffers in agricultural areas: Iowa State: http://www.ent.iastate.edu/ipm/icm/1999/6-14-1999/riparian.html USDA (includes worksheet): http://muck.soils.ufl.edu/incentive/cp391.html USDA ~ guidelines: http://neirtnt.ct.nrcs.usda.gov/tecguide/ripbuf.htm

Summary of protection resources available to landowners and municipalities As humans develop more and more land for agricultural, industrial, and residential areas, the need to buffer our waterways has become evident. Many organizations, both public and private, and on both regional and national levels have created grants and other financing programs to assist communities and private landowners with the costs of buffering projects. The organizations with the most available money are, for the most part, governmental offices. The Environmental Protection Agency, the US Department of Agriculture, the National Fish and Wildlife Service, and the Minnesota Department of Natural Resources all have large amounts of funding available to cover such costs as land acquisition, environmental consulting, and the implementation of a buffer. Private organizations, such as the Nature Conservancy, also have money available. These grants normally cover 25-100% of the total cost of the program. While there is a certain amount of competition for the most lucrative grants, there are many grants that go unclaimed each year because no one applies for them. A number of groups have studied the economic benefits of buffers as well as the ecological benefits and found them to actually be profitable for the landowner in many cases. For more information on this aspect of buffers please see http://www.ctic.purdue.edu/Core4/Core4Main.html for a comprehensive cost analysis of several types of buffers. While buffer projects can be very expensive, cost should not be viewed as a hindrance to the implementation of a buffer plan because there are many funding options available to help defray the cost of protecting our waterways.