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A Sticky Situation
Have you been by the Las Colonias River Park lately? Maybe on your bike riding along the river front trail or out for a run or walk. If you haven't, add visiting the river park to your list. Things are shaping up nicely.
New vegetation and trees are being planted.
There is more and more green each day. Trees and shrubs line the paths and punctuate the places where people interact with the river.
The city is continuing to do a wonderful job of revegetating and rejuvenating the area. You could say that this is a sticky situation since all these new twigs and branches are coming out of the ground and being watered.
In case you didn't notice our Colorado River got pretty low.
So low that it ran under 600 CFS. The lowest that we will see this spring. The journey to 600 began at the start of April. The gauge that I use for the Las Colonias River Park is the gauge just below the Grand Valley Irrigation Canal (GVIC). This is the start of the 15 Mile Reach, the most critical fish habitat in the state and home to 4 federally endangered fish species. The 15 Mile Reach ends with the confluence of the Gunnison. April is when the GVIC begins to allow the irrigation canal to fill and supply the Grand Valley with water for the season. If you look at the charts below notice a step down in river flow when the water was being diverted into the channel.
The flow continued to decrease and a new phenomenon can be seen as another irrigation system begins to supply the Grand Valley with water. This time the fluttering that can be seen is due to an over flow as the system begins to flow. the overflow spikes the flow as water backs up in the irrigation channel. it is an ebb and flow as irrigation begins.
The timing of irrigation beginning and it still being before the runoff brought our flows down below the recommend 825 CFS for the 15 Mile Reach and all the way below 600 CFS. I keep an eye on these things and set an alert if the flow got below 600 CFS. I wanted to see the state of the river when that happened. I got an alert that evening and so I went down to the river park to see what things looked like.
The river was still running through the park but at a noticeably low level. I sat down by the main event and placed my feet on dry concrete. I sat there in surprise. The plan was to have the park run at 800 CFS and up just below the recommended flow for the 15 mile reach. Ive been watching the flow to understand how much to subtract from the gauge level to get the river park flow. This was puzzling and required more investigation. I learned the next day that 800 CFS is where it should have stopped flowing.
The next morning I came down to the river park to see the features and how dry things were in the day light. As I walked up to see what the mouth of the channel looked like I came upon city workers putting sand bags across the entrance.
Engineering a project as big as the river park is as much nature as it is science. Nature is going to do what it wants to do. Things are going to settle and not turn out exactly as planned. This project is tough too because there is very little gradient in the area. So for as much measuring that can be done a meandering river is still going the throw you a curve;) With flows as low as they were and the river park diverting flow the city had to dam the channel to divert water back into the now very critical 15 Mile Reach. The main habitat for 4 federally endangered fish species which takes priority over our river park. What a sticky situation this is. It would be nice if the river never got this low but it does. and when it does we need to do what we can to keep the river flowing through this critical habitat.
Even though the entrance was dammed water still flowed through the channel. This was great to see because the river park was still performing its primary function of creating habitat.
The features were still doing their job, still providing habitat and oxygenating the water. People were still enjoying the area like these two guys.
Building a river park is no small feat, and with one as exceptional as ours there is only so much planning and science that can be applied before you reintroduce nature into the equation. A river runs through it and as it does it moves and settles making for a wonderful experience but, in the same breadth causing mischief. The mighty sediment swollen Colorado River is an ever changing deposition of sand bars and channels meandering with the rise and fall of the flow. We can only do so much to establish a new channel and then let mother nature take its course changing the environment.
With time things begin to settle making for a literal sticky situation.
The rocks in the creek bed designed to form eddies and features are settling out the silt in the river. This of course is what we would expect when reintroducing the "might" of the Colorado. As the channel runs with higher water sediment deposition will change. At low waters we get all the fine sediments high in the river. At higher flows we should see heavier sediment coming into the channel creating a more natural environment. Mind you that the river park has yet to see a run off.
So we have a sticky situation all around. Plants going in everywhere, having to dam the channel, and sediment settling. But they all have a common theme, they change with time. This river park is brand new and still literally growing.
Growing like the flow of the river which with time has come up to over 4000 CFS
The main event is running nicely and very friendly at this level. Check out this little lady surfing on a boogie board practicing responsible paddling. PFD, Helmet, and to complete the ensemble, flippers.
We are only at the beginning of the river season. Be patient and let things grow, they are only gonna get bigger and better.
If you do visit the river park be sure to stay on the paths and watch your step while things are still taking root. Be respectful and be responsible. See you on the water.