Presentation on theme: "Gravel Push-up Dam Removal, Lower North Fork John Day BPA Project 1998-017-00 A Cooperative Project of: The North Fork John Day Watershed Council & The."— Presentation transcript:
Gravel Push-up Dam Removal, Lower North Fork John Day BPA Project 1998-017-00 A Cooperative Project of: The North Fork John Day Watershed Council & The Monument Soil & Water Conservation District Presented by Alex Conley, Council Coordinator
Fish Habitat in the Project Area Strong runs of native Mid- Columbia Summer Steelhead (ESA-listed as threatened) and Mid-Columbia Spring Chinook Cooler tributaries provide year- round rearing for steelhead and Chinook and spawning habitat for steelhead The Lower North Fork provides migratory and Oct thru May rearing habitat for steelhead and Chinook
Push-Up Dams Irrigators use heavy-equipment to push up streambed gravels into gravel push-up dams. They typically wash out in high flows and need to be reconstructed every summer. Push-up dams are used in shallow water areas to: 1) Create pools deep enough to pump from, or 2) Direct water into a gravity-fed irrigation ditch They are common in the area because they are simple, cheap, legal and effective.
In our area there are three main types of push-ups: Tributary push-up dams Cross-channel push up dams Side-Channel push-up dams
Typical Tributary Push-up Push-up has been blown out by winter high flows, and will be rebuilt in spring
Installation and washing out of dams cause regular disturbance to the streambed and adjacent riparian areas, impeding riparian succession and channel development
Pools and side channels created by push-up dams can increase water temperatures FLOW
Installing push-up dams requires regular use of heavy equipment in the stream
Program Goals Our goal is to work with irrigators to install effective diversion systems that: 1) Do not impede fish passage 2) Allow for natural processes of riparian succession and channel development 3) Meet all criteria for fish screening 4) Do not require regular in-stream use of heavy equipment 5) Allow for efficient diversion of legal water rights
Three Solutions 1)Move diversions to sites where water depths are naturally deep enough to pump from. 2) Adapt diversions to pump out of shallower water. 3) Install in-stream structures to artificially create required water depths.
Moving Diversions Four diversions moved as part of the project between 1998 and 2000 Permanent pump stations were installed at new pump sites
Moving Diversions: Challenges Requires stable areas with deep water near irrigated lands, so only feasible at selected sites (30%?) Effectively screening permanent pump stations has been challenging Projects quickly become expensive (due to need to install new power line and buried pipeline and transfer water rights) We will continue to move diversions where appropriate, but can not rely on it as our primary strategy
Using shallow-water pump intakes Pacific-Ags Pump-Rite screens easily pump: 120 gpm in 7 water 500 gpm in <11 water Vs. Standard intakes which require ~30 depths
Using Shallow-water Screens Relatively cheap & simple Allows irrigator to chase water as deep spots move over time Slightly harder to handle and install when compared to traditional set ups
Raising Water Levels First lay-flat dam in project area installed in August 2004 Excellent solution for tributary sites with stable channel locations Photos courtesy of Grant SWCD and BOR
The Remaining Challenge Replacing push-ups at large diversions (>500 gpm) that pump from consistently shallow (under 11 inches maximum depth) reaches of the North Fork remains challenging Solutions we are exploring: Rock weir structures (effective in other areas but very expensive) Infiltration galleries (but clayey soils make this a risky strategy) Larger fish-screens adapted for shallow water (none identified to date…)
Results 4 push-up dams were replaced between 1998 and 2000 Lull in activity 2001/2002 due to the challenges with the original strategy, staff turnover & lack of engineering support Efforts in 2003 focused on building engineering capacity and exploring design alternatives 4 push-ups were replaced in August 2004, 2 more scheduled for fall of 2004 Another 4-7 sites are planned for implementation in 2005 Discussions have been initiated with all landowners who maintain push-up dams in the area
Project Progress When the project started there were approximately 30 regularly maintained push-up dams in the project area 1/3 have been retired (8 by this project and another two as part of another North Fork John Day Watershed Council Project) By September 2005 we anticipate having retired between 1/2 and 2/3 of all dams present Complete coverage is feasible within the next 2-3 years
Project Results to Date Fish passage has been improved Artificial side channels are filling in Previously disturbed sites are revegetating At some sites, water is being saved due to increased irrigation efficiencies Monitoring is underway to quantify temperature changes associated with abandoning push-up dams
Improved Fish Passage The degree of pre-project passage barriers ranges from none to severe. All new diversions are designed to meet all applicable NOAA and ODFW standards for passage and screening. Benefits are greatest in tributary settings where push-ups act as total barriers to juvenile fish during low flow periods- exactly when fish are searching for cold-water refugia.
Photomonitoring indicates artificial side channels are filling in Artificial side channel abandoned in August 2000, photographed in Nov. 2003
Artificial side channel abandoned in August 1998, photographed in Nov. 2003 And sites are revegetating:
Reductions in Water Use Data from a Pilot System, installed August 2004: Maximum pumping load = 100 sprinklers Average size of worn sprinkler nozzles = 7 gpm, for a pumping rate of 700 gpm. We renozzled to 5 gpm nozzles for a rate of 500 gpm. Reduced use by 30%, leaving 200 gpm/.45 cfs instream Irrigator is no longer over-irrigating crop and will see reduced electric bills. Cost of nozzles was ~$50; We saved the ~$2,000 extra that would have been required to install larger screens sized for the original pumping rates.
Temperature Monitoring Initial monitoring shows up to a 5 ºF increase in water temperature in pools created by push up dams at some sites More in-depth monitoring is underway starting in the summer of 2004
Summary The project addresses a significant need Solutions are carefully tailored to individual sites Significant progress has been made in 2003-4 On-the-ground results are already apparent 2-3 years of additional work will enable us to retire most (if not all) push-up dams in the project area
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