That is Penner Lake.
Take 80 east past Yuba gap. Exit at highway 20 and go back towards Grass Valley (the only way you can go).
Watch for Bowman Lake Road on the right. Turn right and go past Fuller lake. Continue for several miles until you see signs pointing to the right. Those signs will be on dirt roads. The first big one is for Grouse Ridge. The next one will say "Carr/Feeley lakes, Linsey Lake. Take that dirt road for about 2 miles. Do not take any side road, just stay on the main road.
You will arrive at a parking area for Carr Lake. Hike past Carr and Feeley lake, Delaney Lake and then an un-named lake on your left. Turn north when the trail splits.
I point out the direction to Penner lake near the beginning of this video.
Keep in touch if you want. Depending on the weather I wouldn't mind going.