From the LA Times March 2

Runyon Canyon, the popular hiking and dog-walking park in the Hollywood Hills with sweeping views of Los Angeles, will be closed for four months starting in April, city officials said.

The cause for the temporary closure is an aging 6-inch water main that stretches a mile through the park, according to the Los Angeles Department of Water and Power.

All of the 137-acre park, except for the yoga field, will be closed to the public starting April 1, when crews will begin replacing the pipeline, according to a spokesman for City Councilman David Ryu, whose district includes the park.

Other Places to Hike – Daily News