Aquatic weed chokes water supply for Lindsay, Strathmore


Water districts up and down the Central Valley are participating in a massive dewatering of the 152 mile Friant-Kern Canal to allow for chemical treatment on a 23 mile segment to fight Western watermilfoil, an aquatic weed that can grow 10 ft long that is clogging canals,water meters and micro irrigation sprinklers alike.

“It’s a huge problem” says Scott Edwards of Lindsay Strathmore Irrigation District who says the invasive weed “grows like kelp – forming huge mats of vegetation that are impeding water flow from Orange Cove all the way to Bakersfield.”

To make matters worse – when the canal water – filled with weed fragments – is pumped to irrigation spigots and micro-irrigation emitters, the small weed particles are covering tiny filters that protect the devices.

“I’ve got 1000 meters out there in the district that need to be cleaned by hand and in this summer, they needed to be cleaned again a few hours later” adds Edwards.

The aquatic weed was first noticed in the Valley’s most important canal in 1998 near Hwy 180 and since has spread at least 23 miles south,well into Tulare County, says Eric Quinley maintenance manager for the 28 district Friant Kern.

How did it get there?

One story suggest somebody may have dumped their aquarium in the canal. “Nobody really knows,” adds Quinley.

The problems has been getting worse particularly where the canal is earthen instead of concrete, says Quinley, through the Orange Cove and Stone Corral water districts.The earth allows the weed to plant itself and reproduce – to take root although this tough customer can attach itself in any crack in the concrete too.

The upshot is that the capacity of the vital canal that irrigates one million acres is increasingly compromised says Quinley. But it gets worse at the canal turnouts where each district takes water,requiring that maintenance staff clear the intake systems regularly right when water is most needed.


Floating Nightmare

The plant fragments and spreads rapidly in a nightmare scenario, the fragments grow roots,stems and leaves as they float along on the current.So the water carries the debris of this invasion with it – creating havoc wherever it flows. And it will be back next year – the plant is perennial.

“This plant poses a problem from the district all the way to the end user – the grower in the field” notes Quinley.

In recent years growers have dramatically cut back on water use adopting micro irrigation technology that is now vulnerable to clogging from the plant’s voracious growth. The Delano area on the canal route was hit hard this summer as this communication to growers explains.

“While it has had a presence in the Friant Kern canal for a number of years, 2012 was the first year that it became a major problem for Delano Earlimart ID. Milfoil has caused a number of operational problems for the District and its growers alike, from plugging pump intakes to clogging filter screens and emitters. The problem became so acute that at one point in August, the entire District shut down for a short period of time when milfoil completely clogged the trash screens within the Friant Kern, preventing water from entering the District’s mainlines. The milfoil has be-come so invasive and present in such massive quantities within the Friant Kern that it has taken the combined efforts” to tackle the problem.

The newsletter explains their staff is required to” keep the district’s intakes clean, requiring milfoil removal by hand twice a day, seven days a week just to keep water flowing …”

Quinley,who is in charge of doing battle with this dragon-like pest, doesn’t have a sword to slay the monster but does have a budget and a plan. So far, the Friant Water Authority has had to budget more than $1 million to handle this weed invasion but has high hopes this winter’s pre-emergent application will make headway in reducing the scale of the problems.

With work underway this month to begin the dewatering of the entire 152 mile canal for a 3 month period there are operational issues that must be tackled including the fact that municipal and ag contractors along the route will not have access to any water from the canal until March1, sooner if it can be managed.


A Drinking Problem

That‘s a problem in Orange Cove where 12,000 customers depend on the water for drinking along with irrigation customers who often don’t have much groundwater.

In Orange Cove the city council has had to spend $750,000 for a temporary supply of well water brought into the city. Improvements are required to convey the well water purchased from land owners through the Orange Cove irrigation District to the City water treatment system.Treatment is necessary due to the high level of nitrates found in the well water says a city staff report.

Canal water is used for drinking in Lindsay,Strathmore and Terra Bella too,all places with little groundwater and high nitrates too. Lindsay Strathmore ID has municipal customers and supplies them from an alternative well source on the Kaweah River, not high in nitrates.

Quinley says in the past, the district has tried to remove the fast growing plant that grows underwater by hand,using mechanical devices and even treating small areas with chemicals but all attempts have fallen well short.

Now with the consultation of USDA and UC Davis the Friant district will go to war with the weed using several pre-emergent chemicals after the canal is dewatered and the silt is removed. The treatment with the chemicals should kill the emerging plant chutes next spring, everyone hopes.

To insure the chemicals applied do not hurt drinking water, Friant has been working with the state Department of Public Health, Department of Pesticide Regulation and the manufacturers to insure no harmful residues remain once the trillions of gallons of water refills the canal in March. The two chemicals- fluridone and imazamox are certified by EPA for use to treat drinking water. Of course the water will be tested before it enters the muni systems next spring.


A Choke Hold

Despite their best efforts this water loving weed like most weeds “may be with us forever” shrugs Edwards.

Farmers may not be big global warming believers but they do believe they that got a plant that was not here a few years ago with choke hold on their hydraulic empire that seems to like the heat.

The National Weather Service says we had 23 days of 100F or over in August in the Valley and across the US, September was the 16th straight month of higher than average temps in a row. The consequence: farmers will have to do battle with this green monster from now on.

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