IDACORP's 2021 second quarter earnings per diluted share were $1.38, an increase of $0.19 per share from last year's second quarter.
Earnings per diluted share over the first six months of 2021 were $2.27, which were $0.33 above the same period last year.
Today, we also increased our full year 2021 IDACORP earnings guidance estimate to be in the range of $4.70 to $4.90 per diluted share, with our expectation that Idaho Power will not need to utilize in 2021, any of the additional tax credits that are available to support earnings under its Idaho of regulatory settlement stipulation.
You'll see on Slide five that the growth remained strong in the second quarter, increasing 2.9% since June 2020.
As of the end of June, unemployment in our service area was 3.5% compared with 6% in June 2020 and the current mark of 5.9% nationally.
Total employment in our service area has increased 6% over the past 12 months.
Moody's forecasted GDP calls for very strong economic growth of 7.6% in 2021 and 6.9% in 2022.
And just this past week, Lamb Weston announced a $415 million investment in the planned construction of a new French fries processing line at its existing facility in American Fall with expected capacity to produce more than 350 million pounds of frozen French fries and other potato products annually by mid-2023.
This expansion is expected to add approximately 130 jobs.
Current weather projections for August through October shows 50% to 60% chance of above-normal temperatures and a 33% to 50% chance of below-normal precipitation in Idaho Power service area.
Idaho Power hit a new all-time peak load of 3,751 megawatts on June 30, and we have exceeded the previous 2017 peak demand of 3,422 megawatts, more than 60 separate hours on 12 different days so far this summer.
And our company also recently issued a request for proposal to add another 80 megawatts of a capacity resource to meet peak energy needs by summer 2023.
B2H will allow Idaho Power to import up to 500 megawatts, which will help meet customers' peak summer demand and increased reliability for our system as well as the region.
Our Idaho rates currently reflect a recovery time line through 2034, but preliminary analysis indicate the potential exit of all four units at the plant sooner than the current time line.
If our filing with the Idaho Commission is approved as filed, rates would increase $30.8 million in December of this year.
Exiting the Jim Bridger plant early also aligns with our goal to provide 100% clean energy by 2045.
On our last earnings call, I stated Idaho Power did not plan to make -- do not plan to file a general rate case in Idaho or Oregon in the next 12 months.
I also commend them for their resilience over the past 17 months as we navigate the challenges of the pandemic together.
On the table of quarter-over-quarter changes, you'll see our continuing customer growth added $3.9 million to operating income.
Also, increased usage per customer drove operating income higher by $22.9 million.
Irrigation and residential per customer usage increased 25% and 10%, respectively.
A return to more normal economic conditions combined with the hot weather also drove a respective 12% and 8% increase in usage per customer in the commercial and industrial classes.
Continuing down the table, the higher usage for residential and small general service customers was partially offset by $5.1 million lower revenues from the PCA -- or the FCA mechanism.
Next, you'll see a decrease in operating income of $6.8 million that relates to the change in the per megawatt hour revenue, net of power supply costs and power cost adjustment impacts quarter-to-quarter.
Recall that Idaho customers generally bear 95% of power supply cost fluctuations.
The heatwave also affected transmission wheeling-related revenues, which increased operating income by $3.9 million.
In addition, wheeling customers paid 10% more for Idaho Power's open access transmission tariff rate that increased last October to reflect higher transmission costs.
Next on the table, other operating and maintenance expenses increased by $5.3 million.
Finally, our higher pre-tax earnings led to an increase in income tax expense of $4.2 million this quarter.
The changes collectively resulted in a net increase to Idaho Power's net income of $9.6 million, or $0.19 per share.
Cash flows from operations were about $39 million higher than the first six months of last year.
We now expect IDACORP's 2021 earnings to be in the range of $4.70 to $4.90 per diluted share.
Recall that above a 10% return on equity in the Idaho jurisdiction, Idaho customers would receive 80% of any excess earnings.
Our expected full year O&M expense guidance remains in the range of $345 million to $355 million.
We also reaffirm our capex forecast for this year in the range of $320 million to $300 million -- $330 million, excuse me.

Summary:
IDACORP's 2021 second quarter earnings per diluted share were $1.38, an increase of $0.19 per share from last year's second quarter.
Today, we also increased our full year 2021 IDACORP earnings guidance estimate to be in the range of $4.70 to $4.90 per diluted share, with our expectation that Idaho Power will not need to utilize in 2021, any of the additional tax credits that are available to support earnings under its Idaho of regulatory settlement stipulation.
We now expect IDACORP's 2021 earnings to be in the range of $4.70 to $4.90 per diluted share.