During winters with normal rainfall, the lake used to be filled by diversion from San Francisquito Creek to a three-meter depth along with artificial water level maintenance, allowing recreational use by students. However, the lake has not been artificially filled since the late 1990s, due to problems either with the lake's damming walls or with conservation efforts.
As the lake is no longer permanently filled, it serves as a drainage basin and contains vernal pools throughout the winter and spring months. It is during this time that it serves as a vital breeding ground for many amphibians.
Those who enjoy exercise can take advantage of the lake's scenic perimeter to jog or walk without distraction on the Script error: No such module "convert". trail. Many dormitory residences, row houses, and several fraternities are located near the lake, including the Lagunita residences, Roble Hall, Enchanted Broccoli Forest (EBF), Narnia, Kappa Alpha, and Jerry.
- California tiger salamander (Ambystoma californiense): During the winter, the lake is the breeding ground for a population of California tiger salamanders, which are classified as vulnerable by the IUCN. However, the Lagunita population is believed to be at greater risk because individuals are frequently killed on nearby Junipero Serra Boulevard during their migrations to and from the lake. As a result, a $100,000 system of migration tunnels was placed underground in 2001.
- Western toad (Bufo boreas)
- Pacific chorus frog (Pseudacris regilla)
- S.J. Barry and H.B. Shaffer. "The Status of the California Tiger Salamander (Ambystoma californiense) at Lagunita: A 50-Year Update". Journal of Herpetology 28, No. 2 (June 1994), 159-164.
- Newman, Loren. "Endangered Salamanders to be Protected" The Stanford Daily, May 5, 2008
- Zigterma, Tom. "Lake Lag and its Dam" The Stanford Daily, May 8, 2008
- Lake Lag Trail