Irrigation water, snowmelt, the last frost and river safety
By J&H Digital Services LLCChecked Oct 23, 20264 sources
Spring brings irrigation water, snowmelt and a late last frost. Canals start filling in early April (the Nampa & Meridian Irrigation District said as early as April 1 to April 8 in 2026), with water reaching customers in mid-to-late April. The frost-free season starts around early May. In high-runoff years the Boise River runs high and parts of the Greenbelt can close.
Many valley neighborhoods have a separate line for lawns and gardens, and others use city water. Ask your landlord or which you have and when the district turns water on.
Water levels change constantly and the water is cold and fast. Canals are private property, so playing in or along them is trespassing.
Plant tender vegetables and flowers after the last frost, usually around early May. Cover young plants if a cold night is forecast.
Homes near the Boise River, creeks and canals can flood during spring snowmelt. Check the FEMA flood map, and know that regular home and renter policies do not cover flood.
In high-water years, sections of the Greenbelt close because of dangerous river conditions. Check the city's and county's notices before you go.
State burn permits are required outside city limits starting May 10.
It varies by year and district. The Nampa & Meridian Irrigation District said flows could begin between April 1 and April 8 in 2026, with deliveries to customers in mid-to-late April. Your own district posts the date on its website.
A separate water line in many valley neighborhoods that carries untreated canal or river water for lawns and gardens. It is billed separately from your city water.
The water is cold and moves fast, and levels change constantly as the district fills and adjusts the system. Banks can be steep and slippery, and canals are private property.
In years with heavy snowpack the river runs high in spring and low areas near it can flood. Parts of the Greenbelt have closed because of dangerous river conditions. Check your address on the FEMA flood map.
The frost-free season runs about early May to mid-October, so wait until early May to plant tender plants outdoors.
Fees, rules and providers change. Confirm with the official source before you go.
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