Riparian values

If you look at our waterways from above, you can see a rolling and flowing patchwork of managed lands and natural landscapes, including urbanized neighborhoods, agricultural fields, riparian forest, seasonal channels and open water. More and more we are seeing how our management of these lands influences the others.
Over time, we have seen how the growth of our agricultural, timber and gravel harvesting, urban and suburban development have shrunk the forest-vegetated areas next to rivers and streams. These riparian areas have a special significance in this patchwork and are increasingly recognized for their ecological and social benefits. Riparian areas are not just patches of green next to water. They are the conduits connecting terrestrial and aquatic ecosystems.
The ecological benefits of riparian areas are often referred to as ecosystem services or ecosystem functions. They include:
• Reducing erosion by stabilizing stream banks;
• Supporting nesting, feeding, resting and reproductive habitat for birds, fish and terrestrial animals;
• Filtering overland flow from upland land uses before it enters a stream;
• Providing shade to lower water temperature;
• Supplying large woody debris cover for fish and freshwater shrimp; and
• Filtering and recharging groundwater.
In effect, they protect or buffer the living environment along waterways from the impacts of development. According to Mathias Kondolf of U.C. Berkeley, establishing and maintaining these riparian areas to an adequate width is the single most effective strategy for protecting the ecological benefits of the area.
Trees, shrubs and soils in riparian areas also help to mitigate global warming and greenhouse gas emissions, yet they are one of the most heavily degraded ecosystems. Their increased biomass helps carbon sequestration and increases soil carbon stocks. In the future, we might see riparian areas being restored, purchased and maintained for carbon credits.
In terms of social benefit, riparian areas are a great place to enjoy outdoor recreation and scenery. On a river, trail or on a road, there is nothing like paddling, pedaling, walking or driving through a mature riparian forest. Less fun but extremely important is the flood damage protection that riparian areas provide. During heavy rainfall and runoff events, the extra, undeveloped space around a river is a buffer protecting our homes and property.
The longer, wider and taller the riparian area, the better the ecosystem function. In fact, if a riparian area is too small and too isolated, it may not offer enough ecosystem services for animals to survive, reproduce or migrate. These ecosystem services work on another dimension as well: time. The older and more mature a riparian area is, the greater the value of the ecosystem services it provides and the greater social return. Restoration is very important to riparian corridor management, but conserving and maintaining existing mature riparian areas have more inherent value.
The challenge inherent to land use planning for riparian buffers is how to balance the need to protect threatened, endangered and more common species with our need to maintain our means to grow food, to earn a living and to sustain our traditions and values. A number of local agencies have taken up this challenge. In November 2014, the Sonoma County Board of Supervisors adopted zoning code changes to implement the stream protection policies and rezoned properties to add the Riparian Corridor Combining Zone to all designated streams shown on the General Plan Open Space maps. The protected area includes the streambed, the stream bank and a 50-, 100- or 200-foot streamside conservation area on each side of the stream, as measured from the top of the higher bank. Within each streamside conservation area, only the practices defined in the County Ordinance are allowed.
Sonoma County Department of Agriculture has provided best management practices (BMPs) for agricultural cultivation within riparian corridors and streamside conservation areas (SCAs). The intent of the BMPs is to prevent controllable sources of sediment, nutrients, pathogens and pesticides from discharging into streams.
The Sonoma County Water Agency performs a significant amount of habitat restoration and channel maintenance throughout Sonoma County to protect endangered native species and increase flood protection. In most cases, activities include bank stabilization and replanting of native species, and may include grading and installation of in-stream structures to improve refuge and spawning habitat for protected species.
Go to rrwatershed.org for a full list of references, links and additional reading.
William Stockard works for the Sonoma County Permit and Resource Management Department.