By Robert Lucke
If some Glacier Park officials and Blackfeet tribal members get their way, Lake Sherburne will dry up and in dry years the Milk River could lose 90 percent of its flow.
Lake Sherburne is on the boundary of the Blackfeet Reservation and backs up into Glacier Park at Many Glacier. The dam and lake connect to the St. Mary River and a canal system to divert large amounts of water into the Milk River for irrigation purposes from Havre to Glasgow.
The problem with Sherburne Dam and Lake is two fold. Bull trout and bank erosion.
Scott Guenthner, Billings Bureau of Reclamation hydraulic engineer, is working on the problem.
Take the bull trout. They are close to being put on the endangered species list. Tribal officials feel that low water flows in the winter from Sherburne Dam are hurting the bull trout population.
We are going through the process to see how our management at Sherburne might change. It is very early in the process, Guenthner said. The tribes thinking is they are concerned about bull trout. Right now any water in the creek (below Sherburne) is from tributaries and a little that passes through our gate. Right now we dont have the ability to pass water in the winter. We are looking at modifying the gate to allow water flows in the winter.
In the matter of bull trout, the Bureau of Reclamation doesnt know what kind of water levels the fish need Guenthner stated. They are working with the United States Fish and Wildlife services on targeting good bull trout habitat.
It appears that the main gate letting water out of Lake Sherburne can be either open or closed and is not geared to let lesser amounts of water out from time to time.
Without Sherburne, Milk River stream flows would dwindle.
Take dry years like 1988, St. Marys water was 90 percent of the water that people used in the Milk River basin, Guenthner continued. And some people have talked of taking out Sherburne but letting the canal system stay. 150,000 acre feet of water feed from Sherburne into the Milk River basin per season. Without Sherburne there would be a 60,000 to 90,000 acre foot loss.
Without Sherburne, the Milk River would run into late fall but it would not be able to sustain irrigation during July and August contends Guenthner.
Glacier Park as well has concerns about Sherburne.
I think Glacier is concerned with bank erosion. The dam is built on the park boundary and water is backed up into the park and there is lots of fluctuation in water levels, Guenthner said.
Montana water specialist Marv Cross in the Havre Water Resources Regional office adds more statistics to the importance of Sherburne to Milk River irrigation.
Lake Sherburne stores 60,000 acre feet of water which is transported from the St. Mary River to the Milk River through a canal, Cross said. 60,000 acre feet continue to refill during the season. Lake Sherburne is second in size in the system. Only smaller than Fresno Dam.
What of Milk River irrigation without Sherburne?
It wouldnt work without Lake Sherburne, Cross thinks. Basically it would cut off irrigation in most years.
Government agencies and the Blackfeet tribe are using innovative techniques now to prevent further stream flow corrosion caused by dam fluctuation.
Cottonwoods are along the bank, sort of their sides in places. Like a log cabin. They root, grow and it does a good job in holding stream banks in place, Cross said.
Larry Frederick, Chief Naturalist for Glacier National Park takes another approach to Sherburne Lake and Dam. Glacier officials contend that since it is not natural, it should not be there.
The tribe approached us and asked our position in removing Sherburne Dam. Our position is that if there is anything we can do to return natural conditions to the park, we would support that, said Frederick. We realize that the dam is legal. It was constructed before the park was even created and that there are water rights issues downstream. However, if those issues could be addressed and at the same time return the area to a more natural state, we would be in favor of it.
Now only that but the park has more complaints about the dam being at the entrance to Many Glacier.
There is a secondary issue and that has to do with fluctuating water levels. That is affected the condition of the road into Many Glacier. It is destroying the road, said Frederick. We have spent millions to solve the problems and yet there are millions yet to spend and improve the road. If the dam was removed we would have a more stable road and we would save tax payer funds to keep the road in good shape.
One thing everyone agrees on is that Lake Sherburne is a life line most every year to growing crops in the Milk River Valley.
I dont think people have a clue about what it would do to the economy of this area without Sherburne, Water Specialist Marv Cross added.