Step 1: Give its location and purpose directly:
Sudarshan Lake was a man-made irrigation reservoir near Girnar (Junagadh), Gujarat.
Step 2: Trace its history through three rulers:
Built under Chandragupta Maurya (by Pushyagupta), extended with conduits under Ashoka (by Tushaspa), and repaired after storm damage under the Saka ruler Rudradaman I.
Step 3: Note the inscriptional evidence:
Rudradaman's Junagadh rock inscription records this repair and is prized as an early classical Sanskrit prashasti.
Final Answer:
\[ \boxed{\text{An ancient irrigation lake at Girnar, built under the Mauryas, repaired by Rudradaman I}} \]