Conservancy District now looking to diversion rather than Narrows dam
James Tilson
Staff writer
3-23-2017
MANTI — The Narrows Project is breathing its last gasps.
After receiving the updating report from engineer Richard Noble regarding the progress of the alternative to the Narrows Project Dam, Water Conservancy District Board Chairman Ed Sullivan declared that the Narrows dam and reservoir are very nearly “dead” and the board will go forward with the water diversion alternative.
The report took place at the most recent meeting of the Water Conservancy District Board on Thursday, March 16.
Noble, the principle in the engineering firm Hansen, Allen & Luce, Inc., has been working with the Water Conservancy District for years trying to get Sanpete County’s water from the top of the Wasatch Plateau to the valley.
Last November, Noble showed the board a plan that had the potential to bypass all the hurdles and red tape they had gotten from federal agencies and lawsuits from other counties. The plan was to divert the water flowing in Gooseberry Creek, to which Sanpete County has already established its rights, through a tunnel dug from the plateau to Cottonwood Creek, and from there to the Sanpete Valley. Noble claims the diversion plan has the advantage that all of the project would be on private property, and would not be subject to EPA or U.S. Army Corp of Engineer approval.
“We’ve made a fair amount of progress since out last meeting,” Noble said.
Noble showed the board the results of a ground water investigation that his firm had made. He stated that they wanted to find a location to store the water diverted from the plateau. The ultimate aim would be to divert the water to locations in the valley, and then drill wells nearby where they could withdraw the water.
Noble says his firm studied geology in the areas near where the water could be stored, looking for areas where the soil is more permeable and nearby existing diversion ponds (so as to avoid EPA oversight). They reportedly found 10 locations, mainly east of Mt. Pleasant and Spring City, with possible well sites downhill and just west of both towns. Noble says the study showed that the water could be successfully diverted and harvested without affecting the water tables in those areas.
In summary, Noble told the Water Conservancy Board, “this plan is feasible.”
Noble then discussed revisions to the earlier plan, to take into account the difficulties posed by topography and service. First, Noble talked about the problem of digging a new tunnel. He noted that any excavation project carried risks with it and that he had speculated that the project would be improved if they could use an existing tunnel near the proposed project area. The plan was modified so that there would be three diverting structures, not two. Also, while two of the diverting structures could use gravity to transport the water, one of them would have to pump the water to the tunnel.
According to Noble, all of the project (except for 0.6 miles of water ditch) would be on private property and not subject to federal oversight. The amount of water harvested would be 3,200-acre feet, versus the possible 5,200-acre feet that a dam and reservoir might provide.
Sullivan was quick to point out that a dam would only provide that much water if it were big enough to allow for two dry years storage. If it weren’t that big, the amount of water that could be harvested would probably be the same as the diversion alternative, he said.
In regards to the matter of how the project would have electrical power to run the pumps, Noble says he found that there was a corridor of private land running from Mt. Pleasant to the plateau. Noble theorized that having private property owners pay for new connection fees would help defray the cost of building a new power line to the site.
At the end of his presentation, Noble stated again that the project was feasible, and may even cost a little less than he originally estimated. He said he was “confident that we can shave a couple of million off of the prior estimate.”
Noble also emphasized that this project would not affect Gunnison Reservoir in any way.
Sullivan, in response to a question about the status of the dam and reservoir project, stated, “If the state water engineer approves the diversion project, then the dam is dead.” The board voted to continue with Noble’s efforts to develop the alternative project.
