Threats to Biodiversity, Working Ranches & Recreation
The expansiveness of the BRBNA's landscape is central to the natural, scenic, recreational, and agricultural resources that define the area.  As a result, even a modest level of poorly planned development could damage the integrity of the region's natural resources, the viability of working ranches, and the potential for maintaining and enhancing outdoor recreation.

Biodiversity
The BRBNA's rich biodiversity and natural habitats have endured in large part due to their remoteness and the lack of significant development in the region.  While many important habitat areas are under public and land trust protection, new development in the form of ranchettes, subdivisions, or large estates could severely impact the region's plant and animal communities both directly and indirectly. Some impacts could result from habitat fragmentation as well as the introduction of invasive organisms, while the direct loss of land and species is also threatened by human intrusion.

Habitat Loss and Fragmentation

Habitat loss occurs when human activity displaces habitat lands.  Development is the most obvious cause of habitat loss but habitat can also be severely degraded due to non-resource compatible recreation activities. Even a relatively dispersed pattern of limited development within the BRBNA could result in enough fragmentation to significantly reduce the overall number and diversity of plant and animal species found in the area.  Unmanaged and incompatible recreational pursuits can result in direct impact to sensitive habitats and species, and are also the source of indirect effects from invasive species, pollution, and visitor services.

Invasive Exotic Species

While invasive species pose an ongoing threat to habitat throughout the state, with new development comes the potential for increased introduction of plants and other organisms not native to the region.  If invasive, such species can wreak havoc on native habitat.  They displace native species, competing for water and nutrients, and can seriously alter the natural ecosystem.  Many areas of the BRBNA are already infested with such species as Arundo spp. and Tamarisk spp., but localized efforts are currently underway to control them.  Many public agencies and organizations expend enormous financial and human resources annually aimed at controlling and eliminating invasive species. 

Point and Non-point Source Water Contamination and Other Pollution

Urban and suburban developments and roadways contribute to non-point sources of water pollution such as erosion and runoff.  Erosion results in increased sedimentation of creeks and water bodies, posing a threat to fish and other aquatic organisms.  Runoff is often laden with chemicals from home gardens and driveways as well as city streets and freeways.  Increased construction in the BRBNA, particularly on steep slopes, would no doubt contribute to erosion and runoff at levels that could threaten water quality, ultimately degrading habitat for aquatic species.  Point sources of water pollution originate from legal and illegal discharges of pollutants into creeks and water bodies.  These are most likely to occur during major development activities, through intensive recreational activity such as motorized boating, and as a result of residential sewage problems.  The potential for the creation of point and non-point sources of pollution multiplies considerably as development increases.

Fire Control

Rural development could also have a potentially major impact on biodiversity and habitat due to the fact that a fire-based ecology characterizes much of the BRBNA landscape.  Even a few homes scattered through the hills and valleys results in the need for artificial fuel reduction and the vigorous suppression of wildfires, both of which can have significant adverse effects on ecosystem health.

Impacts of Domesticated Animals

Domesticated animals, introduced by residents or visitors to the region, can disturb and harm native plants and wildlife.  There is ongoing debate about the extent to which domesticated animals should be restricted in protected natural areas.  However, there is ample evidence that domesticated cats can have a major impact on wild bird populations, and horseback riding and dog walking must be carefully managed in public recreation areas to avoid conflicts with hikers and naturalists.

Working Ranches and Farms
As discussed previously, the greatest threat to economic viability of ranches in the BRBNA is regional growth and development that fuels land speculation, and creates pressure to subdivide large agricultural parcels into estate lots or ranchettes. This fragments the working landscape and introduces a host of other challenges to the sustainability of ranching.

Much of the BRBNA's regional character is related to the vast areas of working ranchland that exist in the area.  Currently, working ranches comprise approximately 45% of the BRBNA's total land area, over 300,000 acres.  This represents a significant part of the total BRBNA and is a defining element of the BRBNA's economy and landscape. 

Increasing development of ranchland in the BRBNA could slowly erode the overall economy of ranching by stripping away the necessary land base to maintain sustainable operations.  Although this scenario would appear unlikely given the current size of individual ranches and the collective scale of ranching within the BRBNA, many of California's once vibrant agricultural regions have been transformed by development due to a lack of adequate conservation strategies in the face of escalating growth pressures.

Rising Land Prices

In many parts of California where significant areas of working ranchland have been lost to new development and development-related fragmentation, rising land prices in response to the potential for development served as a critical factor in the regional transformation process.  Land prices related to development are often much higher than land prices related to agricultural and ranching activities.  Incrementally, the loss of parcels to non-ranching activities would make the economics of ranching and farming increasingly unsustainable and conservation purchases more difficult.

Land Use Conflicts

As areas adjacent to working ranches are developed for residential uses, land use conflicts can arise.  New residents attracted by the rural landscape must contend with the reality of noisy equipment, farm vehicles, and odors associated with ranching.  Such conflict can evolve to nuisance lawsuits by neighbors and eventually create a less hospitable climate for ranching and ranch families.  Careful location of trails and other recreation opportunities on adjacent public lands is necessary to avoid promoting trespass and other disturbances of the area's working ranches.

Loss of Agricultural Support Services

Agricultural support services include feed and farm equipment stores, diesel equipped filling stations, and packing and manufacturing facilities.  As working ranches are lost to development, there are fewer ranchers needing such goods and services, often forcing these support businesses to close.  This in turn makes it more costly for the farmers and ranchers that remain to procure these services, as they have to travel farther for them.

National and Global Factors

National and global factors that reduce agricultural viability cannot be controlled locally but are worthy of mentioning as they exemplify the additional challenges facing agriculture and ranching. These factors include changing livestock markets, climatic variability and drought, and the difficultly that U.S. producers have competing in a global market.

Recreation
Approximately 38% of the land in the BRBNA is in public ownership.  However, the existing pattern of ownership is such that areas encompassing significant natural and scenic resources with high recreational value and the potential for providing recreational linkages are only partially protected.  Significant areas of unprotected land are interspersed among protected lands.  Partnerships between the public and private sectors may allow these areas to be secured in order to create a cohesive linked open space system with opportunities for long distance trails and other recreational linkages. 

Losing Opportunities for Nature-Based Recreation Due to Public Policy

Expiration of the existing concession contracts at Lake Berryessa presents the opportunity to implement government policy prohibiting exclusive use of public recreation land and to broaden the range of interests served by including more nature-based recreation.  However, considerable opposition to changing the status quo of exclusive use by trailer owners has created a difficult situation for the Bureau of Land Management, and the direction it will take is still uncertain.

Establishing connectivity between protected areas

In order to fully achieve the desired connectivity, it will be necessary to secure resources to acquire some land, trail easements and important recreational destination sites, as well as the participation of some private landowners.  In some cases, trail access on private property may be untenable due to incompatibility with the interests of the owner.

Integrating the Needs and Plans of Private Landowners

The interfaces between public and private lands in the BRBNA require special attention, not only to avoid conflict between those who recreate on public lands and neighboring private uses – mainly related to trespassing, garbage dumping, and even the shooting of livestock – but also to integrate private land recreational uses such as ecotourism and hunting into the regional context.

Managing Use and Development

Over use of recreation areas can lead to a diminished experience for all.  Excessive commercialization and unmanaged recreational activities can impact sensitive resources and pose conflicts between motorized and more nature-based pursuits.  Adequate resources are essential to enable appropriate planning and management of recreational access and use, and to promote the development of a cooperative relationship among users, volunteers, private landowners and agencies.