Q: I have a creek that runs in the back of my property, roughly 12 – 22 inches deep. I would like to get some type of pump that I could use to water my lawn from the creek. The water would travel 150 feet.
A: Pumping irrigation water from a stream or pond sounds great in theory but it can be really complicated to accomplish in practice.
Your first task is to decide how much water you need for the lawn. A rough estimate is that a lawn needs 600 gallons per 1000 square feet per week. If you have a 10,000 square foot lawn, you’d need 6000 gallons of water.
Next you need to know the flow rate of the stream. You have to know the velocity of the water, in feet per second, and the cross-sectional area of the water in square feet. Multiply the two numbers to get the flow rate in cubic feet per second.
Let’s assume your stream is four feet wide and averages a foot deep. By floating a leaf down a measured length of the creek a few times you find that the water velocity is one-fourth foot per second. Your stream can supply 1 cubic foot of water (8 gallons) per second (4 x 1 x .25 = 1 cu. ft./sec.).
To avoid draining the entire flow, you should plan on removing only a fourth of the total: 2 gallons per second.
An impact sprinkler can apply 4 gallons per minute. If one sprinkler zone of your lawn includes six impact sprinkler heads, you’ll need 24 gallons per minute.
If you have more water than your lawn (or sprinklers) need, you can get down to deciding which pump to buy. Others who have done this recommend 220 volt electric pumps because they are cheaper ($200 – $350) and easier to maintain. You’ll have the cost of installing an electric power line to the creekside. Gasoline powered pumps range in price from $400 to $600.
How large should the pump be? Much of the decision depends on how far the water must travel and how high your lawn is above the stream. The BEST way to buy a pump is to go to a pump/irrigation store with the figures determined above and ask a salesman to help you decide.
As if all this wasn’t complicated enough, you need to find out if removing water from the stream is even legal. The Ga. Dept. of Natural Resources has regulations about how much of the total flow of a stream can be removed. Their concern is that removing water affects wildlife living near the stream.
You will likely need a permit to remove water from your creek. Don’t forget that there is a 25′ State Stream buffer law. Installing a pump may be an intrusion into the stream buffer, but would require a permit from the state EPD and a permit from the Army Corps as well. Water that is not completely contained upon your land is “waters of the state” and all laws pertaining to it’s protection apply, even to private homeowners. If you don’t get a permit and someone downstream complains, you could be subject to a large fine.
Including pump (electrical line), suction tube, backflow preventer, supply pipe, valves, sprinkler heads, etc, I don’t think you can do it for less than $1000.
You’ll only need the system for a couple of months each year. My city water only costs $3.50 per 1000 gallons. Are the savings worth the hassle and equipment expense in your case?