Nevada will have more precious metals pit lakes than any other state in the union, and will consume a considerable portion of Nevada’s scarce water.  The policy of the state of Nevada should be to preserve and protect our water supplies, as well as protect the general public from risks associated with pit lakes.  Nevada code, NAC 445A.429, only defines a standard for pit lakes in terms of a “potential” to degrade groundwater or adversely affect human, terrestrial or avian wildlife.   The term potential is too vague in our view.   In the development of a mine project an assessment is made as to water quality of an anticipated pit lake, and often there is some probability of poor water quality, which could be in violation of NAC 445A.429.  When is this probability so small that the potential to degrade groundwater or adversely affect human, terrestrial or avian wildlife does not exist? How is the state to enforce this statute?

Also significant is the risk to the general public.  As noted above, the amount of water in pit lakes will exceed the total amount of water in all of the man-made reservoirs in Nevada.  While the water in pit lakes is generally going to be degraded, compared to the pre-mine groundwater, many of the pit lakes will be able to support fish and probably water contact recreation.  If they do support fish, it is likely that someone, over the years, will stock the pit lakes with fish able to survive.  If that happens, fisherman will want to get down to the pit lakes, and fences, particularly in the rural areas, are not likely to be sufficient to prevent the general public from getting to the pit lakes for recreational fishing.  These lakes will thus provide an “attractive nuisance” and unless the pit lake walls are stabilized and a safe access is provided, they will become a dangerous attraction.  Reclamation regulations require that the pit lakes are not a hazard to the public, but not a specific use.  Since most of these pit lakes will exist for centuries and beyond, simple fences are not going to be much of a deterrent, and people will want access.

Many of these pit lakes can be turned into a recreational resource, but it will be expensive for resource agencies to make these lakes accessible and safe.  A major policy decision for the state of Nevada is to determine how these pit lakes can be utilized in a productive manner, perhaps primarily for recreation, but at a minimum, for safe access.  If nothing is done, the pit lakes will remain an attractive nuisance and become a liability for both the mining company, but also for the land management agencies.  Arguments can be made that the entities that created the pit lakes have a responsibility to provide a productive post-mining use that minimizes the risk to the general public.

It is worth noting that the Sparks Marina in Nevada, a very valuable recreational lake resource, is a pit lake, and developed following gravel removal for several decades.   The major difference between this pit lake and precious metals pit lakes is that the Sparks Marina rock is well-washed and unreactive gravel, while pit lakes formed from gold and copper mines are generally much more reactive.   However, the recreational potential of many of the gold mining pit lakes also exists.

The Nevada Division of Environmental Protection has developed an in-house contaminate concentration profile for pit lakes.  We see this as a step in the right direction and may help to clarify the application of the regulations (NAC 445A.429).   The mining companies will abide the law as best satisfies their bottom line, and while NDEP does have the authority to designate beneficial use of pit lakes in reclamation the law does not require it.  It may seem reasonable to handle pit lakes on a case by case basis; however, it appears as though without a requirement for beneficial use the lakes sit fallow, dangerous, and our precious water is wasted.

Ultimately, there should be a requirement for a post-mining beneficial use for the water in the pit lake.  Such a requirement will require new mine plans to include reclamation of the pit lake and thus change how the mine is developed.