Bill Hocker | Apr 29, 2019

4/29/19

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Another episode of siltation in the Rector Reservoir water system is reported in the Sun this week

This last year following the fire, a neighbor just uphill from us cleared off the area surrounding the creek that then goes through our property on its way to Rector Reservoir. Removing the dead trees and brush was the right thing to do but there were consequences.

This year, after one of the large storms, an area of our creek, with a three-foot-deep channel, silted up, sending silt overflowing into an adjacent meadow. I was happy to have the additional topsoil but not so happy to have to re-establish the flow-line of the channel. After another storm, the silt was completely gone from the channel, ending up, doubt at the bottom of Rector Reservoir.

It was a demonstration, albeit small, of the relationship between land clearing, heavy storms and the quality of Yountville's drinking water.

There is continuous replanting going on in the Rector watershed, often with deep ripping to remove Smart-car sized boulders that was not done in the old days. There are two major ECP's in process in the watershed totaling 200 acres of new vineyards. And there is still almost a thousand acres of land on which new vineyards are possible in this already most heavily developed of Napa's watersheds.

There is only so much that Best Management Practices, straw and retention basins can do to prevent siltation from newly cleared land in the event of major storms. The runoff from one replanting done two years ago is shown below.

In this era of global warming the types of storms we experienced this last year, and worse, are predicted to become more frequent. The modest proposals made by the Supervisors following Measure C concerns over the development of the watersheds will do very little to reduce the siltation that earthmoving operations in the watersheds are likely to produce. The best protection against siltation, and the best protection for the global warming future that has become all too apparent, is to leave natural vegetation and its soil undisturbed.

The amount land that can be developed into grapes in this small county is finite, and the quantity of wine that can be produced with Napa grapes is likewise limited. (Some might see the rarity as a valuable attribute.) The continued development of the watersheds for vineyards is an attempt to ignore the limits for just a few more years to squeeze a little more profit out of the land before the wine industry must really confront its limited resource. But, as the silting at Rector shows, it a gamble with the quality of drinking water of the people of the county as the wager.

Unfortunately, absent a more rigorous protection of Napa's watersheds, Yountville residents and the residents of the rest of the county that depend on watershed water should probably be looking at home water filtration systems.

Original post 3/22/17

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At the Yountville City Council on Mar 21st, 2017, the residents of Soda Canyon Road presented a white paper on the dangers of the potential pollution of Rector Creek and Rector Reservoir caused by the construction of the Mountain Peak project. The project envisions moving massive amounts of earth around on a constrained site bordering one blue line tributary to the reservoir and bisected by another.

The construction calls for 29,500 cubic yards of cave spoils, another 19,000 cy of other excavation, the removal of approx 7 acres of topsoil so that the excavated spoils can be distributed on the site and then the recovering of the spoils with the topsoil (calculations here). The excavated crushpad, through which all of the cave excavation must be moved, is within 100 ft of Rector tributary. A major fill area, comprising 2 acres of soil removal, placement of spoils and redistribution of topsoil, is just adjacent the tributary that bisects the site. A second area of fill surrounds a wetlands area of the site that also drains within a few hundred feet into the canyon.

The environmental concerns are obvious. Silting from vineyard development in the Rector watershed in the 1990's caused damage to the Rector Reservoir filtration system resulting in millions of dollars in repairs. The county should be requiring Environmental Impact Reports (EIR's) to assess similar impacts on this project and other land clearing projects now going on in the watershed. The Mountain Peak project, with only a negative declaration of environmental impacts, was approved by the Napa County Planning Commission on a 3-1 vote at the beginning of 2017 and an appeal of the decision to the Napa Board of Supervisors was later denied. The BOS decision will now be challenged in court. An EIR should be required.

Rector Watershed White Paper

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