Happy Isles Gage House Relocation and Reconstruction

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The purpose of this project is to relocate the Happy Isles gaging station to a more secure flood-safe location on the opposite (west) bank of the Merced River in east Yosemite Valley. Specifically, this project would: a) construct a new gage house that would contain gaging instrumentation as well as being capable of hosting other scientific equipment including a weather station and web camera on the roof, b) improve efficiency and reliability by connecting to commercial power, c) improve data access via a broadband internet connection, and d) provide display space on the new gage house for interpretive displays. The new gaging station would be approximately 6 feet square and 11 feet in height (see the model station from the Truckee River and respective design drawings). The structure would sit on a concrete slab approximately 20 feet square and be connected to the existing walkways in the area in conformance with ADA requirements. The structure would be designed to adhere to Yosemite architectural guidelines.

Installation will displace a sparse population of two ethnobotanical species--Rubus leucodermus and Ribes nevedensis. This will be mitigated by salvaging these plants pre-construction and replanting their small populations post construction. Additionally, we will collect seeds from native perennial bunchgrass--Bromus carinantus that is also growing there and sow during the early spring or fall post construction.

The project would require the installation of two 2" conduits for sensors to be anchored to the bank and bed of the Merced River. The conduits would be buried up to 18" between the gage house and the river's edge at which point they would be anchored to the surface of the bank down to the gage pool. No excavation of soil or sediment below the ordinary high water mark (bed and banks) would take place. The conduits would terminate no more than 6' into the channel from the bottom of the bank and would be anchored to the bottom of the river by a fence post. The post may be secured by up to 2 cubic feet of concrete if we are not able to drive the fence post in far enough to achieve an adequate anchor.

Additional conduit is needed to bring power and phone to the new gage site (approximately 400'). This conduit would need to be about 18" deep and approximately 1' wide.

During construction, information on the project and its importance will be posted at the Nature Center, at the project site, and at the Happy Isles bus stop.

The old gage house (non-historic) would be removed after one year of side-by-side operation with the replacement gage. It would be replaced with an interpretive exhibit or panel. The historic dry-stack foundation of the old gage would remain in place pending further planning.