Prescott Drainage System West of Wolf Creek Inlet Damaged

On Saturday, March 30, the warmest day of the year so far, I checked the drainage flow rate from the drainage system CLA installed on L. Prescott’s farm fields west of the Wolf Creek Inlet in 2008.  I checked it where it flows into the culvert under Cyrus Trail.  The flow was heavy, but not dangerously so.  But it was slightly turbid, not its usual near spring quality.  See the following movie file: Drainage System Outflow.

So I decided to investigate.  I moved upstream to the Basin 4 standpipe.  For a map of the basins, look at Figure 4 in the Lake Improvement Projects Post called Cyrus Trail Ravine Project.  The Basin 4 standpipe looked like it was functioning normally, with its flow running at about 20% capacity.  See the movie file: Basin 4 Standpipe.  There was no water standing in Basin 4.

I moved further upstream, to the Basin 3 tile outlet.  It was running at full capacity.  See movie file Basin 3 Outlet.  This outlet, along with the outlet from Basin 4, empty into the top of the ravine.

I continued up to the head of the ravine, to Basin 3.  This basin was full, with the water level within 2 feet from the top of the berm!  See the file Basin 3.  Only the top 2 inches of the standpipe were visible and the pool extended north into the next field.  I noticed an ephemeral gully forming uphill from the Basin 3 pool and followed it to its source.  There was water springing from the ground in the middle of the field in two spots that appeared to be immediately above the buried drain tile line from Basin 1.  Here are movies of Blowout 1 and Blowout 2.  Then I checked the Basin 1 Outlet, which delivers its water to the head of a wooded gully to the north.  It’s flow was minimal; much less than the flow rates from the other basin outlets.

I walked up hill to the west to check the condition of Basin 1.  This basin was also full; almost overflowing.  Its standpipe was completely under water.  The water level was within 2 feet of the road which forms its berm.

I believe there is a blockage in the Basin 1 drain tile line between the blowouts and the outlet.  This partial blockage raises the pressure in the line upstream from the block, causing the water to leak from the line at joints or holes in the tile.  Because of this partial obstruction, Basin 1 cannot drain fast enough to keep up with the snow melt runoff.  Also, because of the leakage from the Basin 1 drain, water from that basin is adding to the Basin 3 pool, so it cannot drain fast enough to keep up with the amount of water flowing into it.

If this problem is not fixed, Basins 1 and 3 could overflow their banks, washing away their containment berms and thus washing large amounts of silt down the ravine and into Circle Lake.  The large rush of water will also tear out the vegetation in the bottom of the ravine, thus adding to the ravine’s erosion and adding to the silt flowing into the lake.

I will contact NRCS, SWCD and the land leaseholder to determine the best course of action.

 

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