Workshop Item: - Robert Therres, Public Service Manger
Title
RAIN SENSOR ON RESIDENTIAL LAWN IRRIGATION SYSTEM
Background
The City Council previously discussed the topic of rain sensors on irrigation systems as a measure of water conservation. They were curious as to what other cities are doing. Staff has polled a number of cities - neighboring Blaine, around the Metro and some out state communities. Twenty cities were contacted and 12 responded. Attached to this item is a simple spreadsheet showing their responses.
In summary, at this time most cities do not have ordinances requiring irrigation controls or moisture sensors but most do have some type of water conservation program in place. Andover, Plymouth and Coon Rapids have leveraged some grants to initiate pilot programs. Most cities do have a tiered watering ban. Duluth has a unique situation with an abundant water supply combined with the characteristics of their system that needs a steady supply being conveyed and used.
The State of Minnesota has had an irrigation control requirement in statute since 2003. It reads:
MN State Statute 103G.298: All automatically operated landscape irrigation systems shall have furnished
and installed technology that inhibits or interrupts operation of the landscape irrigation system during periods of sufficient moisture. The technology must be adjustable by the end user or the professional practitioner of landscape irrigation services.
Most cities are in a similar position to Blaine, recognizing the need for water conservation and contemplating what steps they should take. Two common situations provide opportunities for change: 1) lack of control on irrigation systems which results in systems watering during or right after rain events; and 2) irrigation systems that are used when the ground is already saturated from recent rain events. Both scenarios unnecessarily waste water and both can be easily and cost effectively corrected.
Rain sensors and moisture sensors are becoming more available in a wide range of cost and features. Simple rain sensors, costing around $30, will sense rain and turn the system off. More elaborate systems costing $200 to $400 have Wi-Fi internet connections that read weather reports of approaching storms and prevent systems from turning on. Some of these also have moisture sensors that read the water content of the soil and don’t allow the system to turn on until the ground needs additional moisture.
Moisture sensors can cost as little as $20 for a hand held unit that a homeowner can use to test their lawn for water needs. When sufficient moisture is provided by rain events, the lawn needs to dry out a little but before additional water is provided through irrigation. Quick and simple monitoring with the moisture sensor will save water and prevent over saturating the lawn which can lead to a variety of problems.
Some form of control required for new installations of commercial and residential irrigation systems will provide beneficial water conservation measures. As the city looks to renewing the Municipal Water Appropriations permit with the DNR, these are the types of water conservation controls the DNR will look at to measure the commitment of a municipality in conserving ground water.
Recommendation
It is recommended that Council consider an ordinance requiring installation of irrigation controls to conserve water.