Summit Valley Presentations:

• History and current options for Van Norden lake and dam
• Preserving Van Norden Lake and Wetlands through reconfiguration

The Problem

The disposition of Van Norden Lake and its surrounding wetlands is going to be decided in the next two years by the Truckee-Donner Land Trust (TDLT). The venerable Van Norden Dam is currently under the jurisdiction of the California Division of Safety of Dams (DSOD) and they have declared it to be out of compliance and is requiring that it be brought into compliance.

A Solution

The history of the dam in Summit Valley stretches back over more than 100 years (see timeline). Through a chain of serendipitous events the valley currently consists of a blend of five ecological habitats including a 70 acre open water seasonal lake and its adjoining wetlands as well as another 100 acres of wet meadow and riparian habitats. Any solution for fixing the dam will have serious consequences to the habitats in the valley. 

Realistically, the only financially feasible solution for fixing the dam is to reconfigure it so that it is no longer under the jurisdiction of the State. This means that the dam must either be reduced in height to below 6 ft or the volume of the lake must be lowered to below 50 acre-feet. Last summer a bathymetric analysis by Balance Hydrologics showed that the current spillway would need to be lowered 2.2 ft to reduce the lake to 50 acre-ft. Either of these alternatives by themselves will lower the lake significantly and will completely remove the large back bay area of the lake and its adjoining wetlands.

The solution presented here is a way to minimize the effects of remediation and maintain the lake and wetlands and is based on a strategy of divide and conquer. The idea is to divide one large lake that is > 50 acre-ft and jurisdictional, into two lakes that are each less <50 acre-ft and non-jurisdictional.  There is a natural constriction in the middle of the lake where an secondary low profile dam can be constructed. The dam would be an engineered dam consisting of mortared boulders that would be a hybrid between a fully submersible weir and a dam.  The dam would form a second lake approximatley 2 ft in depth that would be <50 acre-ft and out of state jurisdiction (see jurisdiction chart), about 2/3 the size of the current back bay area. The existing dam can be notched down to 2.2 feet which will make it <50 acre-ft and remove it from the jurisdiction of the state.

The result would be a configuration in which there would be 2 non-jurisdictional lakes and the open water lake and wetlands would be maintained. A  win, win!

Consider the Alternative

Of course the simplest solution for bringing the dam into compliance would simply be make it non-jurisdictional by lowering the level of the lake by 2.2 ft so that it holds less that 50 acre-feet of water. This would have drastic consequences for the back bay area of the lake as shown in the simulation graphic included here. This course of action would completely remove the 35 acres of lake in the back bay with its adjoining 35 acres of wetlands. The front bay would also be significantly reduced in size.

Employing the secondary dam solution described above would prevent the loss of the back bay area and it’s wetlands that would occur with a 2.2 ft notching. The simulation below shows what would be expected using a secondary dam and two lake solution. As you can see, there is relatively little impact on the present configuration of the lake and wetlands.

But is it “natural”

It is true that Van Norden lake is the result of the man-made Van Norden dam. However, nature is the ultimate opportunist and for the last 36 years it has established an ecosystem in the valley that includes the open lake and wetland habitats that support a rich bio-diversity resource. Man made lakes and wetlands are a common tool used throughout the United States to foster wildlife and preserve habitat and millions of dollars are spent to create and support these projects. The Sacramento NWR is perfect example just a short distance from the Summit Valley Each year large areas of wetland are created through irrigation in the central valley to provide a winter home for millions (yes millions) of migratory ducks, geese and cranes. If you have never visited one of the reserves to see the Snow Geese fly then you are really missing a special natural experience.

http://youtu.be/fi5QCoQoJRA

Another example of the creation and maintenance of open water and wetlands is the world famous reserve of Bosque del Apache in San Antonio, New Mexico. If you want to see the ultimate example of human powered creation and preservation of this valuable habitat, watch the video below.

When you consider the millions of acres of natural habitat that have been lost in the development of this country, there is something inherently satisfying when with just a little effort we can return some of that habitat back to nature.

What you can do

The disposition of Van Norden Lake and wetlands is in the hands of the Truckee-Donner Land Trust. They must decide on a plan that will address the present situation in which there is a non-compliant dam in the Summit Valley. In October the Land Trust stated that it would go ahead with the plan to notch the existing spillway 2.2 ft to lower the lake volume to <50 acre-ft. The two lake solution has been presented to the Land Trust and they have considered it seriously. They have also shown it to the US Forest Service which is slated to buy the land in the next two years.

The Truckee-Donner Land Trust has made a commitment to resolve this situation to optimize the resources in the Summit Valley. Part of that optimization includes the enjoyment of the valley by the people that visit it, including you. If you agree with the idea that the valley should be maintained in it’s current configuration with the valuable and bio-diverse lake and wetland habitats, then make your feelings known to the land trust. You can do this by attending their special outreach meeting on July 29th at 9 am at Judah Lodge and/or contacting them directly at their website.

So let’s