The first reservoir site I visited was the centerpiece of the former Bonny Lake State Park, located in eastern Colorado outside of Idalia. This park was the furthest east state park in Colorado. Construction of this South Fork Republican River dam wrapped up in 1951, bringing regular water and flood control to the area. Additionally, for over 60 years, water recreation was brought to an area of the state that previously had little.
Bonny Reservoir was fairly modest in size. This diagram illustrates the different capacities of the reservoir. To give that diagram context, here is a picture of the spillway with the former body of the reservoir in the background.
The reservoir held greater than 50,000 acre feet one other year - in June of 1974. Since then, the maximum content generally got up to somewhere around 42,000 acre feet. In terms of elevation, the reservoir generally topped out right at the gated sluiceway elevation, give or take a foot. Up until 2003, that is.
In that year, the Supreme Court decided that Kansas was not receiving its fair share of water from the South Fork Republican River. It was determined that not enough water was making its way to Kansas based on the Republican River Compact, which was implemented in 1942. After the Supreme Court decision, the debt was initially attempted to be paid by sending more water than usual through Bonny Dam. While more water was sent versus years in the past, it was not enough to satisfy the Republican River Compact.
In the year 2000, the maximum elevation of the reservoir was 3,666', close to the average maximum since the reservoir was filled for the first time. From here, the annual maximum slowly slid as more water was sent to Kansas. The following four year maximums are as follows:
This pattern continued until 2011. After years of deliberation and trying to find an alternative to draining the reservoir, no better option was found. Any other option would have been prohibitively expensive and taken too much time to implement. So it was decided that the reservoir would be drained, with the water ultimately making its way to Kansas to satisfy the Republican River Compact. The draining of Bonny Reservoir began at the close of water year 2011 (September 30) and concluded in April of 2012. Since then, the "reservoir" has fluctuated between zero and one acre feet.
Here is a side by side satellite image of Bonny Reservoir at two stages. On the left is an image of the reservoir from June 7, 1995, and on the right January 2, 2014. In the left photo, the reservoir is at an elevation of 3,674', just above the bottom of the gated sluiceway, and holds 44,866 acre feet. In the right photo the reservoir is at an elevation of 3,638 and holds zero acre feet.
|June 7, 1995 on left, January 2, 2014 on right.|
I visited the drained reservoir because I was curious. I've seen many full and partially full reservoirs, but never one that was (intentionally) drained. Especially one that was such an anchor in local recreation. Without knowing any better, I started driving over the dam. The first thing that I saw of note was the concrete spillway pictured above.
|Back of dam and spillway.|
Other than the spillway, I found the high and dry boat ramps to be most interesting. It's been a couple years since any of the boat ramps were used on this reservoir, and they will likely never be used again. It will take an awfully wet period for enough water to both satisfy the Republican River Compact and fill the reservoir. In the meantime, we will have to make do with the area being turned into a state wildlife area.
|Bonny Reservoir as of March 19, 2014|
|June 25, 1999 on left, March 14, 2014 on right.|
here in the reservoir. (The Google Map image is from 8/31/2012, which is why there is more water than when I went.) No idea for sure, but I think I'm facing the southeast. At least I meant to. At this point in my walk the silt was very soft and it was physically demanding to walk. Not quite muddy, and not like walking on a beach. I tried to walk further toward the center of the reservoir, but the silt was getting softer and softer. I decided there was not enough to be gained from walking to the center.
|North boat ramp on Neenoshe|
Next I headed to John Martin Reservoir. Often forgotten, and incorrectly attributed as the third or fourth largest reservoir in the state by capacity, John Martin sits on the Arkansas River in the southeast corner of Colorado. To clear up the size issue, here is the correct order of the four largest reservoirs by capacity in the state of Colorado:
- Blue Mesa Reservoir - This is undisputed and fairly well known. Blue Mesa has a live storage capacity of 829,500 acre feet.
- John Martin Reservoir - Poor John Martin never gets love. Second largest reservoir in the state with a maximum capacity of 603,500 acre feet at top of spillway gates.
- Lake Granby - Third largest in state with a maximum capacity of 539,758 acre feet. Often attributed as second largest, occasionally third.
- McPhee Reservoir - Total capacity of 381,195 acre feet makes this reservoir fourth largest in Colorado by capacity.
|May 8, 1999 on top; July 30, 2006 on bottom|
There are three concrete boat ramps on the John Martin, all on the north shore. Two of the boat ramps are located on the east end, not too far from the dam. In most water conditions both are usable. If the water dips below about 30,000 acre feet, though, only the furthest west ramp will be in the water. Both of these ramps are in the heart of the state park that surrounds the reservoir. The boat ramp that is the most interesting to me is one furthest west.
This boat ramp is located approximately 6.75 miles from the dam (green arrow). As you may haven guessed from the previous information, this ramp has been high and dry for years, and will likely never see water again, especially enough to launch a boat. I drove down this ramp and went as far as I could toward the river. Turns out the park system put up a gate, blocking people from driving too far into the reservoir bed.
|Facing west boat ramp from 1/2 mile away|
|Back at the top of the boat ramp, here's the view looking over what used to be the reservoir. At full pool, the reservoir used to be about a mile and a half wide at this point.|
I'm interested to find out whether or not the reservoir will even be over 200,000 acre feet again. My guess is that it won't ever reach that level again, and probably not even 100,000 acre feet. In its current form, John Martin Reservoir is a very important resource in southeastern Colorado. At nearly any level, it provides valuable resources for the area. As a parting shot, here is the reservoir at 48,000 acre feet as viewed from the dam. Although the reservoir is a shadow of what is has been and could again be, it still provides a decent surface area for recreation.
|John Martin Reservoir from dam as of 3/20/2014.|