Copco Lake Mwc, AZ

Lead detected, under the action levels

Latest 90th-percentile lead: 4.53 ppb (monitoring period 2023-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.

About Copco Lake Mwc

Copco Lake Mwc serves about 181 people through 65 service connections, which makes it a very small system under EPA's size classes. It is privately owned and draws groundwater, in Siskiyou County, Arizona. EPA system ID: CA4700551; phone on file: 530-905-1337. Call that number and ask whether your address has a lead, galvanized or unknown service line.

Copco Lake Mwc's lead record

That is up 4.53 ppb from 0 ppb in the period ending 2019. The highest 90th-percentile result EPA holds for Copco Lake Mwc is 4.53 ppb across 2 monitoring periods, none of them over 15 ppb.

Against other Arizona systems

Of the 730 Arizona systems with a lead result, the median latest reading is 0 ppb; 9 are over 15 ppb right now and 58 have gone over at some point. Copco Lake Mwc's 4.53 ppb sits at the 89th percentile in Arizona and the 89th nationally (higher means more lead).

Your move

Test your own tap with a certified lab first-draw sample; Prescott, AZ may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Copco Lake Mwc whether it covers that cost before hiring anyone - many utilities now do.

These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. What a 90th-percentile result does and does not tell you: how to read a lead result. The action level is dropping - the 10 ppb rule from 2027.