Letter from Stream Ecologist

Letter to Board of Aldermen: A response to comments re: paved roadways in Bolin Forest

Michael J. Paul, PhD

I am writing this letter regarding the adverse impact of paved roadways on Bolin Forest, especially in the riparian zone of Bolin Creek. I am opposed to paving of trails in the forest – the first phase and all subsequent phases. I am an aquatic ecosystem ecologist with specific expertise in freshwater ecosystems, especially streams. I have worked for 15 years as a consulting ecologist on an array of projects including the monitoring and assessment of aquatic ecosystems, the development of water quality regulations to protect aquatic ecosystems under the Clean Water Act, and the risk assessment of aquatic ecosystems including, among many factors, the effects of urbanization and climate change. I have authored more than 20 peer-reviewed scientific articles including a comprehensive review of the effects of urbanization on stream ecosystems, two book chapters (one on urban streams), 10 peer reviewed government guidance documents, and more than 50 technical reports. I currently serve on the Board of Directors of the international Society for Freshwater Science and volunteer with the Friends of Bolin Creek (FOBC) as a scientist, providing expert advice and support on matters related to the Creek, in whose Carrboro portion of the watershed he resides. I am, however, writing this letter as a concerned citizen. My specific comments are as follows and address some of the comments and misconceptions that have been provided to this Board from others[1].

First, paved road have profound impacts on ecosystems [2] –   roads alter soils, alter hydrology, increase erosion, destroy forest habitat, disrupt the natural movement of organisms, and introduce pollutants including from the road material itself. While not opposed to the concept of multi-use paved pathways, if properly constructed and maintained, I believe that these ought to be designed very carefully, with maximum respect for their environmental and social consequences, and ought to be part of a larger transportation strategy that makes maximum use of existing roads which already have environmental controls in place and minimize the requirement of additional impervious cover in watersheds. Greenways are not inherently “green” – they are in fact single lane roads and come with all the impacts a paved roadway makes to any forested watershed. In these comments, we refer to this project as a road – because it is ostensibly a single lane road that is being proposed.

Second, comments have been presented to this Board that paved roadways would be better than the existing paths because the existing natural paths, especially along the OWASA easement, are “already bad”, eroding, or in poor condition. I would not argue that the existing OWASA easements and associated trails have become, in a few locations, essentially impervious surfaces that are contributing to erosion and impacting the stream. Many citizens, including local watershed groups, have been working for years to try and improve this issue with OWASA and the city, to no avail. And this proves exactly a point that these efforts have been asserting about these trails – riparian buffer zones adjacent to streams are not ideal places for trails, but especially not impervious paved ones. Paving over the existing trails at best would make a bad situation no better, at worse they would exacerbate it. The remedy, in stark contrast to the one provided by some recent commenters, is not to pave the trails. Rather, the solution is absolutely the opposite – to commit to restoring these trails to more permeable, stable, natural systems that fulfill the role of a riparian zone.

Riparian zones (the forested ecosystems adjacent to streams) are essential to healthy stream ecosystems – they moderate temperatures, provide organic matter, stabilize stream channels, and filter pollutants from surface and groundwater runoff, among many, many other benefits[3]. These zones are so important to streams that the recent US Environmental Protection Agency (EPA) final rule on the jurisdictional scope of the Clean Water Act (CWA) defining “Waters of the US” grants automatic status of jurisdiction under the CWA to floodplain wetlands and other riparian adjacent waters because of their inherent importance to water quality. These forest ecosystems should simply be left alone to maximize the abundance of the ecosystem goods and services they provide. Ideally, the trails (and easements) should be moved out of the riparian zones to more upland locations.

The riparian zones along Bolin Creek are used as utility easements by OWASA. There are, however, numerous locations along the creek where easements provide more permeable surfaces that infiltrate water, provide some habitat, and do not provide the damaging impacts mentioned in recent comments. Paving would be no kind of solution; rather, it would lock the riparian zone into permanent imperviousness and modification – one that has no way of ever providing the natural functions that contribute to the maintenance of a natural stream. Pavement is a land cover dead end – especially in riparian forests. Its application represents among the most unnatural form of land conversion known. Paving a bike path is not recognized as a water quality solution by anyone. Indeed, the State of North Carolina does not recognize the placement of impervious surface area and the armoring of banks as a valid stream restoration technique. Under Jordan Lake rules the construction of a paved multi-use path/road is allowed within riparian zones; as long as no practical alternative exists (and many clearly do here). Again, paving a road in the riparian zone as a control of erosion does not equate to a valid stream restoration technique. Carrboro would be alone in this belief. We strongly disagree with making the bad condition of streamside habitats worse through paving.

A simple quick glance of the photo of the Morgan Creek trail provided in recent comments (see below) shows many of the negative effects of paved roads next to streams. First, one sees what the natural vegetation along a stream ought to look like on the other side of the creek. One also sees, on the paved side, nonnative plant species including grasses, which thrive adjacent to roadways as a result of ease of transport and removal of native vegetation and which require mowing and other treatment to maintain. Third, one sees river sediment that ought to be deposited on a forested floodplain, but instead is covering the road, requiring road sweeping equipment (trucks). Similarly, fourth, one sees human transportation infrastructure that will require regular maintenance, replacement, policing, emergency access – all of which will require more vehicle traffic, in addition to OWASA trucks, and come at increasing costs to the town. When OWASA removes sections of the road to access their infrastructure for repairs, who bears the costs of repairing the road? In addition, this is infrastructure that will be exposed to regular flooding, including severe flooding of these roads on a regular basis – because they are being placed in a floodplain. Streams flood roughly every 1.5y – but are doing so more frequently now in Bolin Creek due to increased runoff from impervious surface and increased precipitation from climate change[4]. The extreme flooding this year was evident in the damage to the new bike road built along the Umstead road section of Bolin Creek, which is already showing signs of bank failure. Increased flooding will damage the roads, requiring replacement of paved sections regularly at great costs and requiring, again, large machinery. Why waste valuable public resources putting a road in a floodplain that will need constant maintenance and repair? Restoring the natural floodplain will provide a naturally self-sustaining system. Fifth, one sees erosion along the far side of the roadway, likely contributing to additional stream bank erosion in Morgan Creek. Sixth, one sees a stream, a naturally meandering system, constrained by additional human infrastructure from being able to adjust its channel – leading to more severe erosion and flooding downstream. Seven, one sees rip-rap placed to stabilize the land adjacent to the trail, because it is cut into the floodplain and needs to be protected from the natural erosion that ought to occur as part of natural stream function (again, a look at the ill-conceived path along Bolin Creek on Umstead already indicates evidence of erosion of the large rip-rap due to the concentration of hydraulic forces exacerbated by the hard construction associated with the path – one that will only continue to degrade the stream). Eight, one sees the impervious surface, leading to increased runoff and runoff of pollutants associated with the composition of the asphalt/concrete itself.

Third, we don’t need more roads as transit opportunities. We have roads in Carrboro already. A lot of them. Roads are a top predictor of declines in many ecosystem condition indicators – both forest and aquatic[5]. We especially don’t need more roads through our last remaining forested ecosystems. We need to do what forward thinking cities across the US and in Europe are doing – make our roads better and safer for cyclists[6]. Let’s pave smarter and better instead of paving more. Solutions like additional, separate bike lanes and bike lanes separated by medians for protection are just two examples. The list of innovative biking solutions added to existing roadways is extensive. We should be pursuing these instead of destroying some of the last remaining natural space in Carrboro.

Fourth, there are cumulative impacts associated with roads. People have argued that tree removal and paving associated with this one small section of roadway will be minimal and will have minimal effect on loss of carbon sequestration. The argument that one specific environmental impact (e.g., paving roads through Bolin Forest) that is a subset of larger ones (cumulative impervious surface in the watershed) will have no impact is the very epitome of ecological death by a thousand cuts. One could easily argue that Estes Road had minimal impact on tree loss, or Seawell School road alone, etc. It is the cumulative effect of removing forests that matters. At some point you just have to stop removing forest and stop laying down impervious surfaces. We’ve already removed so much that there is little remaining forest left, including the fragile riparian forest along Bolin Creek. Why would we add more when it is unnecessary and when there are viable alternative transportation options that should take advantage of existing paved infrastructure (see above). Bolin Creek should not be a paved “corridor”, as some have described the paved road. It is a natural ecosystem and its riparian forests are integral to its health (see above). We should be restoring that riparian forest and not paving it. And to suggest that the stream would remain “as shaded” is simply untrue. There cannot be pavement without permanent removal of trees followed by paving the soil that is the very definition of irreversible tree cover loss. One has only to look at the recent paving in UNC north to see the large swaths of trees that were removed leaving a much less shaded area. A number one predictor of physical habitat condition decline in Maryland streams was the distance to paved roadways[7]. It is not just shade that is lost when riparian trees are permanently removed – it is the annual leaf input that is a major source of energy to streams, the loss of woody debris that is essential to stream morphology, the loss of soil stabilization by roots, the floodplain habitat critical to the life cycle of myriad insect, amphibians, and fishes and the forest food web that relies on them, etc.[8]

Fifth, it has been suggested in comments that paved roads are the cause of teeming wildlife as opposed to the adjacent vibrant forest itself. This comment deserves little response. The literature on the effects of roads on ecological condition is pretty consistent – they are overwhelmingly negative[9]. Any teeming wildlife is not the result of the pavement. The same birders and wildlife enthusiasts would have equal if not expanded experiences along unpaved trails. In addition, they and the wildlife would be unimpacted by the increased transportation traffic.

Sixth, another comment suggests that a paved greenway provides more safety for cyclists. Unfortunately, this comes at reduced safety for the natural ecosystem. As mentioned above and actually in several of the publications of the cited UNC Highway Safety Research Center, there are a variety of transportation options that provide safer options for cyclists that do not involve paving forests[10]. As others have frequently communicated to the BOA, If paving roads through the forest is absolutely necessary, than Carrboro/Chapel Hill should only use existing roads (e.g., the pumpkin loop, the fire road/power line road, etc.) on the Carolina North Forest, avoiding use of and staying clear of any unique and sensitive areas (including all riparian zones, fragile upland forest, wetlands, etc.), should avoid existing valued trail systems, and should prioritize the use of permeable substrate and state of art green infrastructure stormwater control. The safety of the natural system must also be considered.

Next, this Board has also been told that more users would use paved trails than unpaved. No research, other than anecdotal evidence, is provided for this. We could provide equal anecdotal evidence to the contrary, as any visit to the Bolin Creek watershed trail system would attest. Indeed, the high school cross country team has provided ample testimony. The natural trails have wide utilization as well. Moreover, providing accessible natural areas for those with limited mobility, elderly, and young riders should be a priority but should utilize improvements of existing large infrastructure (e.g., the pumpkin loop) rather than paving forest trails or riparian zones.

Finally, public outreach for this project has been lacking. Many Bolin Creek neighbors, townspeople, naturalists, and school athletes who use the forest for walking, running and biking had no idea of this plan. There have been no signs or public notices in the area where this is planned, an obvious and important way to engage the public in the planning process.

In closing, I am opposed to paving of trails in the forest – this first phase and all subsequent phases. Such large intact forested space is rare and ought to be protected, especially for the vast number of users that already enjoy that space. I am especially opposed to any paving along sensitive stream riparian buffers since that paving represents a severe impact on the associated stream and riparian forest ecosystems with negative impacts well documented in the scientific literature. I would be more than willing to talk to the Board about water quality issues in the Bolin Creek watershed, existing and impending threats, water quality improvements that could be gained by restoring adjacent riparian forest and improving existing right of ways, the negative effects of roads on streams, and to address any questions you have based on my experience and expertise in this area.






Photo of Morgan Creek at James Taylor bridge provided in letter entitled “Responses to statements on paving “natural surface pathways from the 4/26/2016 public comments” by Johnny Randall



[1] Especially the letter entitled: “Responses to statements on paving “natural surface pathways from the 4/26/2016 public comments” by Johnny Randall

[2] Forman, R.T.T. and L.E. Alexander, 1998. Roads and their major ecological effects. Annual Review of Ecology and Systematics 29:207-231.

[3] Wenger, S. 1999. A review of the scientific literature on riparian buffer width, extent and vegetation. Institute of Ecology, University of Georgia, Athens, GA

[4] Paul and Meyer 2001, http://www.ncdc.noaa.gov/news/explaining-extreme-events-2014

[5] Paul and Meyer 2001.

[6] www.makingspaceforcycling.org

[7] Paul, M.J., J.B Stribling, R.J. Klauda, P.F. Kazyak, M.T. Southerland, and N.E. Roth. 2002. A Physical Habitat Index for Freshwater Wadeable Streams in Maryland. Maryland Department of Natural Resources, Annapolis, MD. CBWP-MANTA-EA-03-4

[8] Wenger 1999.

[9] Forman and Alexander 1998.

[10] Rosenblatt, B., Flynn, M., and Sundstrom, C. (2015). Separated bike lanes go mainstream. ITE Journal, 85(10), 39-45;