Open space plan shifts from blunt to refined approach, scaling impact criteria

David Briggs
Some mountain bikers are still dissatisfied with the draft management plan for open space preserves and are asking that evaluation of trails and future improvements include the positive impacts bikers provide, including getting people—in some cases, young people—off dangerous roads. Others suggest that bikers be allowed to ride on narrow trails—currently they are allowed on only four such trails—because they ride more slowly and therefore contribute less to erosion and do less damage to natural resources. County parks officials say they’re through with revisions, but that future community meetings will invite input on specific trails and their best uses.

Outcry over the proposed decommissioning of roads and trails in Marin’s Open Space District has led officials to shift to a finer-toothed approach to management.  At a public meeting on Saturday, representatives of Marin County Parks laid out a new method to evaluate projects that will be part of a revised draft Road and Trails Management Plan due for release this summer with an accompanying environmental impact report. 

“We’re trying to nail it this time so we can start building things. Otherwise we’re in an endless loop of planning,” said Linda Dahl, the director and general manager of the parks department. Ms. Dahl said she hopes the district can soon find “big, sexy projects so that people like this process.”

From April to August, Ms. Dahl and her staff will solicit project proposals from the public. These can range from decommissioning to rerouting trails to the construction of new ones. The district will then rank the proposals for consideration in the 2015-2016 budget. 

Regardless of which projects are chosen, their net impacts to the district’s 34 preserves will have to decrease every year—both over the entire network and within each of six geographic areas. Since a new trail inevitably introduces impacts, those proposals will have to be accompanied by a project in the same region to offset the environmental damage. 

The previous version of the draft plan—blasted by hikers, bikers and equestrians—measured impacts of roads and trails based on their surface area, with fewer square feet equaling fewer impacts. But the proposed reductions in road and trail area did not sit well with users, and the criteria for choosing projects was vague, officials admitted.

The new draft plan will forego that approach to decommissioning. “We changed the metric pretty dramatically,” said Carl Somers, the chief of planning and acquisition for the parks department who was hired in January.

Instead, the road and trail plan expands the use of a limited tool in the original draft plan, which evaluates current trails and proposed projects based on a large array of possible environmental impacts.

The district will score projects based on 23 biological and physical criteria, including proximity to salmon spawning, interference with rare plant habitat, intersections with wetlands, trail slope, trail width, soil type, intersections with weedy areas (since people can inadvertently spread their undesirable seeds) and stream crossings. If a road or trail crosses a perennial stream, the score would “get a whack.”

Impacts are mostly tallied on a scale of one to five, with five representing the greatest impact. Some particularly sensitive criteria, like spotted owl habitat and serpentine soil, are scored on a one-to-10 scale and are given more weight in order to discourage new trails or encourage fewer impacts. Projects on existing trails will be given a “before” and “after” score, ranked from 0 to 130.

The district is now using this scaling system to measure the effect of three maintenance projects that it will tackle this year at Roy’s Redwoods in the San Geronimo Valley, Cascade Canyon near Fairfax and Dawn Falls in Larkspur. At the Roy’s Redwoods loop trail, the installation of new footbridges, resurfacing of the trail and leveling of steep areas will cut erosion and reduce sediment impacts to the ephemeral streams that feed San Geronimo Creek. Those improvements will lower the trail’s score from 62 to 32.

Mr. Somers does not believe the new evaluation method will stretch the resources of the district or cost more money; in fact, he expects the opposite, since physical criteria accounts for future maintenance. 

“It’s more efficient because we’re directly measuring those things, as opposed to going on faith that reducing overall size will be cheaper… A rational person would expect that if you’re building considerations for maintenance and sustainability into your decision-making matrix, you will make better decisions.”

There are also seven social criteria to measure how pleasing a trail might be, accounting for the variety of plant life, undulations and views it affords. The district says that will help them compare projects in terms of how much they might benefit the public.

Each fiscal year, the total scores of projects in the district must show a net decrease in impacts. “This is not a trail development prevention matrix,” Ms. Dahl said at the meeting. “This is what it takes in today’s environment to do a responsible job of introducing new development [into open space].” 

Although the park conducted an evaluation of the system in 2011 to create a baseline, there is no numerical target for an acceptable level of impact to the district. But given the plan’s expected lifespan, Mr. Somers doesn’t think they’ll run out of work to do. “If we’re making incremental changes as we go throughout the 10 to 15-year life of the plan, we will make steady improvements, but I don’t think we’re gonna go so far as to over-improve the area,” he said. 

Many in the audience on Saturday seemed pleased with the general direction of the changes, but fears remained, particularly regarding bike access. 

Larry Nigro, a teacher who bikes to San Geronimo School every day, said he was happy that more depth had been incorporated into the process but believed the district should account for the historic use of social trails, or unofficial trails created by people walking and moving across the landscape.

These trails won’t be slated for decommissioning by the district, even if they are never included in an official map of the system. (Trails that were illegally constructed by active digging—paths the district refers to as “improved trails”—will be decommissioned over time.)

Ms. Dahl said that social trails are for hikers—not dogs, not horses and not bikes, which worried Mr. Nigro, who bikes on a social trail twice a day. “How do I ride to work?” he asked her. 

Vernon Huffman, a Woodacre resident and the head of the nonprofit Access4Bikes, also expressed concerns that the district wanted to prohibit bikers and dog walkers from social trails. 

Ms. Dahl said that over the next two years or so, there would be meetings for each of the district’s six regions, to discuss the road and trail network and get proposals for new or modified trails. When the time comes for San Geronimo Valley’s meeting, he needed to be present, she responded.

Other bike advocates advanced the idea that trails should garner better scores if they encourage bikers to leave roadways because of the dangers they face alongside cars. They also argued that making narrow trails more available to bikers would address both the environmental concerns of biking, since wide trails are more erosive and disperse more sediment, as well as safety concerns, since mountain bikers ride more slowly on narrower, winding trails. Currently they can only bike on about a quarter of narrow trails in open space, despite the rapid growth of the sport, Mr. Huffman said.

“If we can spread out mountain biking around the county and open up more opportunities, in the end we have a safer trail network because we’ve spread out the use,” he told the Light

The future of expanded bike access will remain unclear until projects are proposed and approved. But however long that takes, “There will be more trail mileage for bikes, open to bikes, than there is now, at some gauge narrower than a road,” Mr. Somers said.