San Bernardino County sheriff's deputies and city officials said they are also concerned that the house, which many call a mansion, at 15250 Woodglen Drive, is an illegal Chinese maternity operation.
The women allegedly come to the house in their last trimester but conceal their pregnancy from U.S. customs officials. Once born, the baby is a U.S. citizen.
Mayor Art Bennett said city Code Enforcement officials visited the house last week inquiring about a septic tank issue and noticed new construction.
"There was a lot of improvements to make individual rooms," Bennett said, "and they found out upon further investigation that they were renting those rooms out as motel rooms to bring in Chinese expectant mothers to the United States and these people are paying substantial fees to stay in that residence until they have their child."
For months, residents said they noticed a lot of activity in the neighborhood as vehicles and vans went to and from the house.
Code Enforcement officials have been watching the house since September because 2,000 gallons of sewage was discharged into the city's storm drain system and the county's Flood Control Channel, city officials said.
"At first, we thought drugs, prostitution or human trafficking," said Linda Spencer, who lives down the street from the Woodglen Drive house.
"Then, we contacted the Chino Hills Sheriff's Department and they told us they would check into it then they showed us pictures and I thought this is a residential neighborhood and they're running a commercial hotel and it needs to be shut down."
Code Enforcement officials visited the property last week with an inspection warrant and issued a cease-and-desist order based on several violations, Bennett said.
"This home is not meant to be a hotel by any means, plus there is a septic tank overflow and sewer spillage," he said.
"This is a single family residential home that is being operated as a hotel and it isn't zoned for that and based on that it needs to be shut down."
City officials are dealing with the code enforcement issues, but not with the alleged illegal maternity operation, Bennett said.
The house is also in violation for "operating a hotel in rural residential zone district" and for "using the single family custom home for other purposes than what is permitted," according to Code Enforcement documents.
The property was also in violation of constructing additional rooms, installing more air conditioning units and electrical outlets.
Sabrina Chen, listed as the contact for property owner, Hai Yong Wu, on a Sept. 18 city code compliance order, when reached by phone on Friday said she could not speak about the property.
"I am just a translator. I am not the owner," Chen said. "I cannot say anything about the property owner. He is out of town."
The concerned residents have started a grassroots group called Not in Chino Hills and created a website that detailed their concerns at notinchinohills.org.
They are protesting at 10 a.m. today at the corners of Peyton Drive and Chino Hills Parkway.
"I think everyone is shocked as to why they came to Chino Hills and the only conclusion I have is the home is secluded," said Rosanna Mitchell, a Not in Chino Hills member and resident of the city.
"There are a lot of homes that have a large acreage and the city is affluent and beautiful."
Mitchell, along with Spencer, alleged the group is also renting rooms at Green Valley Apartments, 14901 Frost Ave.
"I think they've been running this illegal business for eight months and no one has known about it and now we hear there are two locations, the home, and now Green Valley Apartments," Mitchell said.
Calls late Friday to Green Valley Apartments were not reurned.
Mitchell said asiamchild.com details how women in their last trimester should go about coming to America to get a visa.
"For me, I was born in Peru and my dad came here when I was young and he came here and worked hard to get money to get a Visa ..." said Mitchell, who is also a Chino Hills City Council candidate.
Reach Canan via email, call her at 909-987-6397 ext. 425, or find her on Twitter @ChinoValleyNow.