At 6.1 square miles (16 km²) in size, the watershed of Salt Creek is the smallest major watershed in the county.
Shaped roughly like a "Y", the two arms of the mostly residential watershed represent the drainage basins of Salt Creek and its major tributary, the Arroyo Salada Storm Channel.
Bounded almost entirely by the San Joaquin Hills, the watershed consists of a hilly region east of the Aliso Creek watershed, south of the Sulphur Creek drainage basin, and west of the valley of San Juan Creek and Trabuco Creek.
The easternmost part of the watershed lies within San Juan Capistrano, and the southernmost part between Dana Point and Laguna Beach.
Two-thirds of the watershed lies within the city of Laguna Niguel.

If not for the uplift of the San Joaquin Hills approximately 1.2 million years ago, the Salt Creek watershed may have a different geography altogether.
The unnamed tributary that now is diverted into the Arroyo Salada Storm Channel was once part of the course of Sulphur Creek, a tributary of Aliso Creek to the north.
The historic creek had a length of around 7 miles (11 km), far longer than the present-day mainstem of Salt Creek.
At that time, the Sulphur Creek-Arroyo Salada combination would have represented the mainstem of the Salt Creek watershed, draining southward towards the Pacific, and would have added over 4 square miles (10 km²) to the Salt Creek watershed.
A low saddle now divides the two drainage basins.

Effects of Channelization
Due to channelization during urban development, the source of Salt Creek, which was a small marshy wetland but has been replaced by a community pool, is no longer where it was before the area was developed in the 1990s.
At that point, The flow of Salt Creek is channeled into storm drain K01P07, which ends about 1/2 mile to the northeast of the original source at 33.52508, -117.68814.
The various storm drains and the obliteration of the original source have in effect moved the source to an area completely under the street of Marina Hills.
In addition, the flow of the stream is almost entirely urban runoff during dry seasons.
This is evidenced by a constant annual flow, albeit low, which is low in life and the fact that it is choked with stringy algae, the growth of which is stimulated by nitrates from yard fertilizer.
Also as a result of this intense channelization, Salt Creek has no surface tributaries and is inhospitable for all but the smallest mosquito fish and tadpoles.
Oftentimes, there are soap suds visible on the water's surface, originating from the many residential and commercial entities in the watershed.
At 6.1 square miles (16 km²) in size, the watershed of Salt Creek is the smallest major watershed in the county. Shaped roughly like a "Y", the two arms of the mostly residential watershed represent the drainage basins of Salt Creek and its major tributary, the Arroyo Salada Storm Channel. Bounded almost entirely by the San Joaquin Hills, the watershed consists of a hilly region east of the Aliso Creek watershed, south of the Sulphur Creek drainage basin, and west of the valley of San Juan Creek and Trabuco Creek. The easternmost part of the watershed lies within San Juan Capistrano, and the southernmost part between Dana Point and Laguna Beach. Two-thirds of the watershed lies within the city of Laguna Niguel.
If not for the uplift of the San Joaquin Hills approximately 1.2 million years ago, the Salt Creek watershed may have a different geography altogether. The unnamed tributary that now is diverted into the Arroyo Salada Storm Channel was once part of the course of Sulphur Creek, a tributary of Aliso Creek to the north. The historic creek had a length of around 7 miles (11 km), far longer than the present-day mainstem of Salt Creek. At that time, the Sulphur Creek-Arroyo Salada combination would have represented the mainstem of the Salt Creek watershed, draining southward towards the Pacific, and would have added over 4 square miles (10 km²) to the Salt Creek watershed. A low saddle now divides the two drainage basins.
Effects of Channelization
Due to channelization during urban development, the source of Salt Creek, which was a small marshy wetland but has been replaced by a community pool, is no longer where it was before the area was developed in the 1990s. At that point, The flow of Salt Creek is channeled into storm drain K01P07, which ends about 1/2 mile to the northeast of the original source at 33.52508, -117.68814. The various storm drains and the obliteration of the original source have in effect moved the source to an area completely under the street of Marina Hills. In addition, the flow of the stream is almost entirely urban runoff during dry seasons. This is evidenced by a constant annual flow, albeit low, which is low in life and the fact that it is choked with stringy algae, the growth of which is stimulated by nitrates from yard fertilizer. Also as a result of this intense channelization, Salt Creek has no surface tributaries and is inhospitable for all but the smallest mosquito fish and tadpoles. Oftentimes, there are soap suds visible on the water's surface, originating from the many residential and commercial entities in the watershed.
Salt Creek (Orange County)